[Federal Register Volume 74, Number 194 (Thursday, October 8, 2009)]
[Rules and Regulations]
[Pages 52014-52064]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E9-24039]



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Part IV





Department of the Interior





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Fish and Wildlife Service



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50 CFR Part 17



Endangered and Threatened Wildlife and Plants; Listing Lepidium 
papilliferum (Slickspot Peppergrass) as a Threatened Species Throughout 
Its Range; Final Rule

  Federal Register / Vol. 74, No. 194 / Thursday, October 8, 2009 / 
Rules and Regulations  

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DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17

[RIN 1018-AW34]
[FWS-R1-ES-2008-0096]
[MO 922105-0008-B2]


Endangered and Threatened Wildlife and Plants; Listing Lepidium 
papilliferum (Slickspot Peppergrass) as a Threatened Species Throughout 
Its Range

AGENCY: Fish and Wildlife Service, Interior.

ACTION: Final rule.

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SUMMARY: We, the U.S. Fish and Wildlife Service (Service), determine 
that Lepidium papilliferum (slickspot peppergrass), a plant species 
from southwest Idaho, is a threatened species under the Endangered 
Species Act of 1973, as amended (Act). This final rule implements the 
Federal protections provided by the Act for this species. We have 
determined that critical habitat for L. papilliferum is prudent but not 
determinable at this time.

DATES: This rule becomes effective December 7, 2009. The effective date 
has been extended to 60 days after publication in the Federal Register 
to allow the U.S. Bureau of Land Management (BLM) to finish conferring 
with the Service under section 7(a)(4) of the Act on the BLM's issuance 
of grazing permits within the range of Lepidium papilliferum.

ADDRESSES: This final rule is available on the Internet at http://www.regulations.gov and also at http://www.fws.gov/idaho. Comments and 
materials received, as well as supporting documentation used in the 
preparation of this rule, will be available for public inspection, by 
appointment, during normal business hours at: U.S. Fish and Wildlife 
Service, Idaho Fish and Wildlife Office, 1387 S. Vinnell Way, Room 368, 
Boise, ID 83709; by telephone at 208-378-5243; by facsimile at 208-378-
5262.

FOR FURTHER INFORMATION CONTACT: Jeff Foss, Field Supervisor, at above 
address, telephone, and facsimile, or by electronic mail at: 
[email protected]. Persons who use a telecommunications device for 
the deaf (TDD) may call the Federal Information Relay Service (FIRS) at 
800-877-8339.

SUPPLEMENTARY INFORMATION:

Background

    Lepidium papilliferum is a small, flowering plant in the mustard 
family (Brassicaceae). The plant grows in unique microsite habitats 
known as slickspots, which are found within the semiarid sagebrush-
steppe ecosystem of southwestern Idaho. The species is endemic to this 
region, known only from the Snake River Plain and its adjacent northern 
foothills (an area approximately 90 by 25 miles (mi) (145 by 40 
kilometers (km)), or 2,250 square miles (mi\2\) (5,800 square 
kilometers (km\2\)), with a smaller disjunct population on the Owyhee 
Plateau (an area of approximately 11 by 12 mi (18 by 19 km), or 132 
mi\2\ (342 km\2\). The restricted distribution of L. papilliferum is 
likely due to its adaptation to the specific conditions within these 
slickspot habitats. The absence of all perennial plant species from 
these sites likewise demonstrates the specialization of L. papilliferum 
persisting in the unique conditions provided by slickspots (Fisher et 
al. 1996, p. 16). The primary threat to L. papilliferum (as described 
under The Present or Threatened Destruction, Modification, or 
Curtailment of Its Habitat or Range, below) is the present or 
threatened destruction, modification, or curtailment of its habitat and 
range due to the increased frequency and extent of wildfires under a 
wildfire regime modified and exacerbated by the spread of invasive 
nonnative plants, particularly nonnative annual grasses such as Bromus 
tectorum (cheatgrass). In addition, even under conservative projections 
of the consequences of future climate change, the threats posed by 
wildfire and the invasion of B. tectorum are expected to further 
increase within the foreseeable future. Other threats to the species 
include competition and displacement by nonnative plant species, 
development, potential seed predation by harvester ants, and habitat 
fragmentation and isolation of small populations.

Previous Federal Actions

    On July 15, 2002, we proposed to list Lepidium papilliferum as 
endangered (67 FR 46441). On January 12, 2007, we published a document 
in the Federal Register withdrawing that proposed rule (72 FR 1622). 
For a description of Federal actions concerning L. papilliferum prior 
to the 2007 withdrawal, please refer to that 2007 withdrawal document. 
The withdrawal of the proposal to list L. papilliferum was based on our 
conclusion that, while its sagebrush-steppe matrix habitat is becoming 
increasingly degraded, the best available data at the time provided no 
evidence indicating that this degradation was impacting L. papilliferum 
within its slickspot microsites. Furthermore, we concluded that, 
although we found that abundance on the Idaho Army National Guard's 
Orchard Training Area (OTA) had decreased in recent years, the observed 
rangewide fluctuations in population numbers appeared to be consistent 
with varying levels of spring rainfall, as expected. On April 6, 2007, 
Western Watersheds Project filed a lawsuit challenging our decision to 
withdraw the proposed rule to list L. papilliferum. On June 4, 2008, 
the U.S. District Court for the District of Idaho (Court) reversed the 
decision to withdraw the proposed rule, with directions that the case 
be remanded to the Service for further consideration consistent with 
the Court's opinion (Western Watersheds Project v. Kempthorne, Case No. 
CV 07-161-E-MHW (D. Idaho)).
    After issuance of the Court's remand order, we published a public 
notification of the reinstatement of our July 15, 2002, proposed rule 
to list Lepidium papilliferum as endangered and announced the reopening 
of a public comment period on September 19, 2008 (73 FR 54345). The 
initial comment period closed on October 20, 2008. After the close of 
the comment period, new information became available that was relevant 
to our evaluation. Much of this information was contained in reports 
based on several independent analyses of the available information 
regarding L. papilliferum population trends on the OTA in southwest 
Idaho, the rangewide Habitat Integrity and Population (HIP) monitoring, 
and a recent analysis of L. papilliferum data collected on the Inside 
Desert (Owyhee Plateau) from 2000 to 2002. To ensure that our review of 
the species' status was complete, we announced another reopening of the 
comment period on March 17, 2009, for a period of 30 days (74 FR 
11342). We posted several documents on http://www.regulations.gov for 
public review and comment, including the additional information and 
statistical analyses we received after the January 2007 withdrawal 
notice (72 FR 1622; January 12, 2007). A summary of the comments we 
received and our responses is provided in this document, following our 
finding.

Species Information

Description
    Lepidium papilliferum is an intricately branched, tap-rooted plant, 
averaging 2 to 8 inches (in) (5 to 20

[[Page 52015]]

centimeters (cm)) high, but occasionally reaching up to 16 in (40 cm) 
in height. Leaves and stems are covered with fine, soft hairs, and the 
leaves are divided into linear segments. Flowers are numerous, 0.1 in 
(3 to 4 millimeters (mm)) in diameter, white, and four petalled. Fruits 
(siliques) are 0.1 in (3 to 4 mm) across, round in outline, flattened, 
and two-seeded (Moseley 1994, pp. 3, 4; Holmgren et al. 2005, p. 260). 
The species is monocarpic (it flowers once and then dies) and displays 
two different life history strategies--an annual form and a biennial 
form. The annual form reproduces by flowering and setting seed in its 
first year, and dies within one growing season. The biennial life form 
initiates growth in the first year as a vegetative rosette, but does 
not flower and produce seed until the second growing season. Biennial 
rosettes must survive generally dry summer conditions, and consequently 
many of the biennial rosettes die before flowering and producing seed. 
The number of prior-year rosettes is positively correlated with the 
number of reproductive plants present the following year (ICDC 2008, p. 
9; Unnasch 2008, p. 14; Sullivan and Nations 2009, p. 44). The 
proportion of annuals versus biennials in a population can vary greatly 
(Meyer et al. 2005, p. 15), but in general annuals appear to outnumber 
biennials (Moseley 1994, p. 12).
Seed Production
    Depending on an individual plant's vigor, the effectiveness of its 
pollination, and whether it is functioning as an annual or a biennial, 
each Lepidium papilliferum plant produces varying numbers of seeds 
(Quinney 1998, pp. 15, 17). Biennial plants normally produce many more 
seeds than annual plants (Meyer et al. 2005, p. 15). Average seed 
output for annual plants at the OTA (an Idaho Army National Guard 
(IDARNG) training area on BLM land) was 125 seeds per plant in 1993 and 
46 seeds per plant in 1994. In contrast, seed production of biennials 
at this site in 1993 and 1994 averaged 787 and 105 seeds per plant, 
respectively (Meyer et al. 2005, p. 16). Based on data collected from a 
4-year demography study on the OTA, survivorship of the annual form of 
L. papilliferum was demonstrated to be higher than survivorship of 
biennials (Meyer et al. 2005, p. 16). For example, of the 4,065 plants 
counted in spring of 1993, a total of 2,503 survived to fruit as 
annuals, while only 85 survived to fruit as biennials in spring of 
1994. Meyer et al. (2005, p. 21) hypothesize that the reproductive 
strategy of L. papilliferum is a plastic response, meaning that larger 
plants will flower and produce seed in their first season, whereas 
smaller plants that stand less chance of successfully setting seed in 
their first season will delay reproduction until the following year. 
The biennial life form is thus maintained, despite the higher risk of 
mortality.
    Like many short-lived plants growing in arid environments, above-
ground numbers of Lepidium papilliferum individuals can fluctuate 
widely from one year to the next, depending on seasonal precipitation 
patterns (Mancuso and Moseley 1998, p. 1; Meyer et al. 2005, pp. 4, 12, 
15; Palazzo et al. 2005, p. 9; Menke and Kaye 2006a, p. 8; Menke and 
Kaye 2006b, pp. 10, 11; Sullivan and Nations 2009, p. 44). Mancuso and 
Moseley (1998, p. 1) note that sites with thousands of above-ground 
plants one year may have none the next, and vice versa. Above-ground 
plants represent only a portion of the population; the seed bank (a 
reserve of dormant seeds, generally found in the soil) contributes the 
other portion, and in many years constitutes the majority of the 
population (Mancuso and Moseley 1998, p. 1). Seed banks are adaptations 
for survival in a ``risky environment,'' because they buffer a species 
from stochastic (random) impacts, such as lack of soil moisture (Baskin 
and Baskin 2001, p. 160).
Seed Viability and Germination
    The seeds of Lepidium papilliferum are found primarily within the 
slickspot microsites where the plants are found (Meyer and Allen 2005, 
pp. 5, 6). Slickspots, also known as mini-playas or natric (high sodium 
content) sites, are visually distinct openings in the sagebrush-steppe 
created by unusual soil conditions characterized by significantly 
greater sodium and clay content relative to the surrounding area 
(Moseley 1994, p. 7). The vast majority of L. papilliferum seeds in 
slickspots have been located near the soil surface, with lower numbers 
of seeds located in deeper soils (Meyer et al. 2005, p. 19; Palazzo et 
al. 2005, p. 3). Lepidium papilliferum seeds have been found in 
slickspots even if no above-ground plants are present (Meyer et al. 
2005, p. 22; Palazzo et al. 2005, p. 10). When above-ground plants are 
present, flowering usually takes place in late April and May, fruit set 
occurs in June, and the seeds are released in late June or early July. 
Seeds produced in a given year are dormant for at least a year before 
any germination takes place. Following this year of dormancy, 
approximately 6 percent of the initially viable seeds produced in a 
given year germinate annually (Meyer et al. 2005, pp. 17, 18). When 
combined with an average annual 3 percent loss of seed viability, 
approximately 9 percent of the original seed cohort per year is lost 
after the first year. Thus, after 12 years, all seeds in a given cohort 
will likely have either died or germinated, resulting in a maximum 
estimated longevity of 12 years for seeds in the seed bank (Meyer et 
al. 2005, p. 18).
    Billinge and Robertson (2008, pp. 1005-1006) report that both small 
and large Lepidium papilliferum populations share similar spatial 
structure, and that spatial structuring within its unique microsite 
slickspot habitats suggests that both pollen dispersal and seed 
dispersal are low for this species and occur over short distances 
(Robertson et al. 2006a, p. 3; Billinge and Robertson 2008, pp. 1005-
1006). Modeling of dispersal and seed dormancy characteristics of 
desert annual plants predicts that plants with long-range dispersal 
will have few dormancy mechanisms and thus quick germination (Venable 
and Lawlor 1980, p. 272). Contrary to this prediction, however, L. 
papilliferum has delayed germination (Meyer et al. 2005, pp. 17-18), 
and, therefore, according to the model, may not disperse long 
distances. The primary seed dispersal mechanism for L. papilliferum is 
not known (Robertson and Ulappa 2004, p. 1708), although viable seeds 
have been found outside of slickspots, indicating that some seed 
dispersal is occurring beyond slickspot habitat (Palazzo et al. 2005, 
p. 10). Additionally, beginning in mid-July, entire dried-up biennial 
plants and some larger annual plants have been observed to break off at 
the base and are blown by the wind (Stillman, pers. obs., as reported 
in Robertson et al. 2006b, p. 44). This tumbleweed-like action may have 
historically resulted in occasional long-distance seed dispersal 
(Robertson et al. 2006b, p. 44). Ants are not considered to be a likely 
disperser despite harvesting an average of 32 percent of fruits across 
six sites (Robertson and White 2007, p. 11).
    Lepidium papilliferum seeds located near the soil surface show 
higher rates of germination and viability (Meyer and Allen 2005, pp. 6-
8; Palazzo et al. 2005, p. 10) and the greatest seedling emergence 
success rate (Meyer and Allen 2005, pp. 6-8). Viable seeds were more 
abundant and had greater germination rates from the upper 2 in (5 cm) 
of soil (Palazzo et al. 2005, pp. 8, 10), while Meyer and Allen (2005, 
pp. 6-8) observed the upper 0.08 in (2 mm) optimal for germination. 
Deep burial of

[[Page 52016]]

L. papilliferum seeds (average depths greater than 5.5 in (14 cm)) can 
entomb viable seeds and may preserve them beyond the 12-year period 
previously assumed as the maximum period of viability for L. 
papilliferum seeds (Meyer and Allen 2005, pp. 6, 9). However, seeds 
buried at such depth, even if they remain viable, are unlikely to 
regain the surface for successful germination. The effects of 
environmental factors such as wildfire on L. papilliferum seed dormancy 
and viability are currently unknown, although L. papilliferum abundance 
is reduced in burned areas (see discussion of Wildfire under Summary of 
Factors Affecting the Species).
Pollination
    Lepidium papilliferum is primarily an outcrossing species requiring 
pollen from separate plants for more successful fruit production and 
has a low seed set in the absence of insect pollinators (Robertson 
2003a, p. 5; Robertson and Klemash 2003, p. 339; Robertson and Ulappa 
2004, p. 1707; Billinge and Robertson 2008, pp. 1005-1006). Lepidium 
papilliferum is able to self-pollinate; however, with a selfing rate 
(rate of self-pollination) of 12 to 18 percent (Billinge 2006, p. 40; 
Robertson et al. 2006a, p. 40). In pollination experiments where 
researchers moved pollen from one plant to another, fruit production 
was observed to be higher with pollen from distant sources (4 to 12.4 
mi (6.5 to 20 km) distance between patches of plants) compared to fruit 
production for plants pollinated with pollen from plants within the 
same patch (246 to 330 feet (ft) (75 to 100 meters (m)) distance within 
a plant patch) (Robertson and Ulappa 2004, p. 1705; Robertson et al. 
2006a, p. 3).
    Fruits produced from fertilized flowers reach full size 
approximately 2 weeks after pollination (Robertson and Ulappa 2004, p. 
1706). Each fruit typically bears two seeds that drop to the ground 
when the fruit dehisces (splits open) in midsummer (Billinge and 
Robertson 2008, p. 1003).
    Known Lepidium papilliferum insect pollinators include several 
families of bees (Hymenoptera), including Apidae, Halictidae, 
Sphecidae, and Vespidae; beetles (Coleoptera), including Dermestidae, 
Meloidae, and Melyridae; flies (Diptera), including Bombyliidae, 
Syrphidae, and Tachinidae; and others (Robertson and Klemash 2003, p. 
336; Robertson et al. 2006b, p. 6). Seed set was not limited by the 
number of pollinators at any study site (Robertson et al. 2004, p. 14). 
Studies have shown a strong positive correlation between insect 
diversity and the number of L. papilliferum flowering at a site 
(Robertson and Hannon 2003, p. 8). Measurement of fruit set per visit 
revealed considerable variability in the effectiveness of pollination 
by different types of insects, ranging from 0 percent in dermestid 
beetles to 85 percent in honeybees (Robertson et al. 2006b, p. 15).
Genetics
    The majority of species in the genus Lepidium have a base 
chromosome count of eight (Mummenhoff et al. 2001, p. 2051). Chromosome 
numbers for pollen mother cells in L. papilliferum ranged from 15 to 17 
(n = 15.96  0.16; Table 3; Figure 3), confirming that the 
plant is a tetraploid (has four sets of homologous chromosomes, as 
opposed to the more usual set of two) (Robertson et al. 2006b, p. 38).
    The genetics of Lepidium papilliferum have been studied using 
samples collected from areas across the entire range of the species 
(Stillman et al. 2005, pp. 6, 8, 9; Larson et al. 2006, p. 14 and Fig. 
4; Smith et al. in press, pp. 15-16). Genetic exchange can occur either 
through pollen or seed dispersal. Some researchers consider L. 
papilliferum to be closely related to L. montanum, and L. papilliferum 
was originally described as L. montanum var. papilliferum in 1900 by 
Louis Henderson. Results of genetic studies comparing L. papilliferum 
with L. montanum indicate that L. papilliferum forms a monophyletic 
group or subgroup that is genetically distinct from L. montanum (Larson 
et al. 2006, p. 13 and Figs. 4, 8; Smith 2006, pp. 5-7, Fig. 1). A more 
recent study examining the relationship between L. montanum, L. 
papilliferum, and L fremontii found that L. papilliferum is considered 
a sister taxa or closely related to L. fremontii, a native mustard of 
western North America (Smith et al. in press, pp. 15-16). Both L. 
fremontii and L. papilliferum are morphologically and ecologically 
distinct from L. montanum, and recent analyses reflect that both are 
monophyletic (organisms that share a common ancestor) with apparently 
little gene flow between them and L. montanum (Smith et al. in press, 
p. 18).
    Some genetic differences have been observed between Lepidium 
papilliferum occurring on the Snake River Plain (now separated into the 
Boise Foothills and Snake River Plain regions) and the Owyhee Plateau. 
Plants in the Snake River Plain and the Owyhee Plateau populations are 
separated by a minimum of 44 mi (70 km), which is considered beyond the 
distance that insect pollinators can travel or that seed dispersal can 
occur. Sites in the Snake River Plain with fewer numbers of plants (16 
to 746 flowering individuals) had less genetic diversity than sites 
with larger numbers of plants (more than 3,000 flowering individuals) 
(Robertson et al. 2006b, p. 42; Billinge and Robertson 2008, p. 1006), 
although this correlation between population size and genetic diversity 
was not evident in the Owyhee Plateau region (Stillman et al. 2005, p. 
9; Robertson et al. 2006b, p. 41). The lowest values for average number 
of alleles per locus were detected in two of the smallest populations 
(Seaman's Gulch in the Boise Foothills region and Orchard in the Snake 
River Plain region); in contrast, the largest number of alleles per 
locus was detected in the second largest population (Kuna Butte SW in 
the Snake River Plain) (Robertson et al. 2006b, Table 4). Larson et al. 
(2006, p. 14 and Fig. 4) also found geographically well-defined 
populations of L. papilliferum between the Snake River Plain and Owyhee 
Plateau based on genetics. In contrast to the Stillman et al. (2005) 
study, Larson's findings indicate the possibility of depressed genetic 
diversity in L. papilliferum based on significantly greater average 
similarity coefficients within collection sites of L. papilliferum 
compared to those of L. montanum (Larson et al. 2006, p. 13).
    In summary, recent genetic studies thus confirm that Lepidium 
papilliferum is a full species distinct from L. montanum. The currently 
accepted taxonomy recognizes Lepidium papilliferum (Henderson) A. Nels. 
and J.F. Macbr. as a full species (Taxonomic Serial No. 53383, 
Integrated Taxonomic Information System (ITIS), 2009). In addition, 
populations of L. papilliferum in the Owyhee Plateau demonstrate 
distinctive genetic differences from individuals in the Snake River 
Plain, likely a reflection of the isolation of these two populations 
due to limited seed dispersal and the limited range of pollinators, 
resulting in little current gene flow between them. Finally, there is 
some evidence that L. papilliferum has reduced genetic variability 
relative to other native species of Lepidium, such as L. montanum, and 
that smaller populations of L. papilliferum have less genetic diversity 
than larger populations.

Monitoring of Lepidium papilliferum Populations

    There are several biological programs designed to monitor 
populations of Lepidium papilliferum over time, and, in some cases, its 
habitat as well. The primary monitoring programs are

[[Page 52017]]

described here to assist in understanding subsequent references to them 
in this document.
    The Idaho Natural Heritage Program (INHP) uses element occurrences 
(EOs) to broadly describe the distribution of Lepidium papilliferum and 
assigns rankings to each EO based on measures of habitat quality and 
species abundance. EOs of L. papilliferum are defined by grouping 
occupied slickspots that occur within 1 km (0.6 mi) of each other; all 
occupied slickspots within a 1 km (0.6 mi) distance of another occupied 
slickspot are aggregated into a single EO. The definition of a single 
EO is based on the distance over which individuals of L. papilliferum 
are believed to be capable of genetic exchange through insect-mediated 
pollination (Colket and Robertson 2006). Due to the nature of their 
definition, individual EOs may differ greatly in size, based on whether 
there are many occupied slickspots distributed widely across the 
landscape relatively close to one another (which would comprise a 
single, large EO), or whether there are only a few (or even a single) 
slickspot(s) that occur close together but are relatively isolated from 
other occupied slickspots (which would comprise a single, small EO).
    Each EO is assigned a qualitative rank defined by population size 
and habitat quality; EO ranks are periodically updated when new ranking 
information becomes available. Currently, no Lepidium papilliferum EOs 
are ranked A, which is defined as an EO with greater than 1,000 
detectable above-ground plants occurring in the best habitat and 
landscape quality. The habitat quality rank diminishes from the highest 
of A to the lowest quality of D. An E ranking signifies that at least 
one plant was observed, but no abundance, habitat, or landscape data 
are available (Colket et al. 2006, p. 4). A rank of F indicates the 
most recent survey failed to find any L. papilliferum plants. A rank of 
H indicates L. papilliferum plants have not been documented at that 
location since 1970 based on old herbarium records with geographically 
vague location descriptions, such as a town name. A rank of X indicates 
L. papilliferum plants had been extirpated from that EO, based on 
agricultural conversion, commercial or residential development, or 
other documented habitat destruction where L. papilliferum plants had 
been previously recorded. An EO can also be ranked as X if it receives 
an F rank five times within a 12-year period (Colket et al. 2006, p. 
4). The current rankings for L. papilliferum are reviewed below in the 
section Element Occurrences Rangewide.
    The Habitat Integrity Index (HII) program conducted by the Idaho 
Conservation Data Center (ICDC, now the INHP) was the first rangewide 
effort aimed at monitoring Lepidium papilliferum and its habitat. The 
HII was initiated in 1998 and ran for 5 years through 2002 (Mancuso and 
Moseley 1998; Mancuso et al. 1998; Mancuso 2000, 2001, 2002, 2003). 
Although 52 transects were established over the years, a total of 17 
transects were sampled during all years of HII monitoring (Mancuso 
2003, p. 3); no rangewide monitoring of L. papilliferum was conducted 
in 2003. Monitoring was initially based on a system of transects of 
varying lengths across the range of L. papilliferum, each subjectively 
located to include 10 slickspots on sites known to contain L. 
papilliferum (summarized in Sullivan and Nations 2009, p. 33; see 
Mancuso et al. 1998 for details). The primary goal of the HII 
methodology was to assess the overall habitat condition, including 
attributes associated with the slickspots and the sagebrush-steppe 
habitat; L. papilliferum abundance was assessed categorically (assigned 
to a range of values) in this program.
    In 2004, the HII was replaced by the Habitat Integrity and 
Population (HIP) monitoring protocol, also implemented by the ICDC. HIP 
monitoring has been conducted annually since its implementation, thus 5 
years of HIP data are now available (through 2008) (ICDC 2008, p. 2; 
State of Idaho 2008). The HIP protocol was designed to provide data 
more replicable and specific to the monitoring required for the 
Candidate Conservation Agreement (CCA) developed by the State of Idaho, 
BLM, and others in 2003 (State of Idaho et al. 2003). HIP presents 
measures of habitat, disturbance, and plant community attributes at 
each transect as well as counts of L. papilliferum rosettes and 
reproductive plants observed (with the exception of 2004, which still 
utilized categorical assessments of plant abundance). Similar to the 
HII protocol, HIP is based on transects of varying lengths subjectively 
located to include 10 slickspots along their lengths (see Colket 2005 
for details on the HIP methodology); however, the HIP protocol includes 
a significantly greater number of rangewide transects, having increased 
from the original 70 established in 2004 to 80 today (ICDC 2008, p. 3).
    HIP monitoring has been annually conducted since 2004 and consists 
of the following procedures: (1) Establish and permanently mark HIP 
transects; (2) record location information; (3) take photographs; (4) 
measure population, habitat, and disturbance attributes at selected 
slickspots; (5) measure plant community attributes; and (6) analyze and 
describe the results (Colket 2008, p. 3).
    The INHP's EO records and the HII-HIP monitoring programs cover the 
entire range of Lepidium papilliferum. In addition, monitoring that has 
occurred within a subset of the species' range, on the Idaho Army 
National Guard's Orchard Training Area (OTA), provides particularly 
important information on the status of L. papilliferum due to the long-
term nature of the monitoring programs. The sagebrush-steppe on the OTA 
is considered to be some of the highest-quality habitat remaining 
within the range of L. papilliferum, and the OTA is home to one of the 
largest and most expansive EOs of the species (Sullivan and Nations 
2009, p. 22). Two of the OTA programs have been monitoring the same 
locations annually (with a few exceptions) since the early 1990s, and 
hence provide up to 18 years of population data for L. papilliferum. 
These two monitoring programs are known as rough census areas and 
special-use plots; both are conducted by staff or contractors of the 
OTA.
    The methods of the rough census monitoring areas are presented in 
Sullivan and Nations 2009 (pp. 28-29). Briefly, the program began in 
1990 by monitoring 5 areas but expanded to the current total of 15 
rough census areas by 1994; the combined extent of the rough census 
areas on the OTA is 866.1 ac (350.5 ha). Counts are conducted by 
technicians who walk across parallel transects 66 ft (20 m) apart and 
record the total number of Lepidium papilliferum individuals observed 
in any occupied slickspots that are found; reproductive status is not 
noted. The sizes of the 15 rough census areas differ, ranging from 4.1 
ac (1.7 ha) to 138.3 ac (56.0 ha), and not all areas have been 
monitored in all years; thus, analyses of the data must be standardized 
by transforming the raw count data to plant density (number of plants 
per unit area) to account for these differences (Sullivan and Nations 
2009, p. 36). Using density as the index of population abundance 
instead of total counts also allowed for the use of 18 years of rough 
census data, from 1990 through 2008 (there were no counts in 1999), 
although only a few of the rough census areas were monitored in the 
earlier years.
    The special-use plots are also located on the OTA. Although called 
``plots,'' these are actually a series of 16 belt transects, each 
containing a single

[[Page 52018]]

slickspot (see Sullivan and Nations 2009, pp. 29-33, for details). A 
stake is centered in the single slickspot, and each year the number of 
Lepidium papilliferum individuals with a 16.4-ft (5-m) radius of that 
stake (comprising a 32.8-ft (10-m) diameter circle) are counted 
(additional habitat information is collected from the remainder of the 
belt transect). Lepidium papilliferum abundance estimates for each of 
the 16 central circular plots has been collected annually each year 
from 1991 through 2008; thus, 18 years of special-use plot data are 
available. As all special-use plots were the same size and were 
surveyed in all years, estimates of abundance are based on reported 
total counts of individual plants (Sullivan and Nations 2009, p. 37). 
Beginning in 2000, the special-use plot data distinguished between 
blooming and nonblooming individuals.
    All of these programs provide information regarding the status of 
Lepidium papilliferum and its habitat, and will be referenced 
throughout this rule. In addition, we reference L. papilliferum 
Management Areas, which are units containing multiple EOs in a 
particular geographic area with similar land management issues or 
administrative boundaries as defined in the 2003 CCA (State of Idaho, 
p. 9). At a larger scale is the L. papilliferum (or ``LEPA'') 
Consideration Zone, an area also designated by the 2003 CCA and defined 
as all areas that may or do contain L. papilliferum (State of Idaho 
2003, p. 21). The LEPA Consideration Zone includes the entire range of 
the species, including all Management Areas and all EOs.

Ecology and Habitat

    The native, semiarid sagebrush-steppe habitat of southwestern Idaho 
where Lepidium papilliferum is found can be divided into two plant 
associations, each dominated by the shrub Artemisia tridentata ssp. 
wyomingensis (Wyoming big sagebrush): A. tridentata ssp. wyomingensis-
Achnatherum thurberianum (formerly Stipa thurberiana) (Thurber's 
needlegrass) and A. tridentata ssp. wyomingensis-Agropyron spicatum 
(bluebunch wheatgrass) habitat types (Moseley 1994, p. 9). The 
perennial bunchgrasses Poa secunda (Sandberg's bluegrass) and Sitanion 
hysrix (bottlebrush squirreltail) are commonly found in the understory 
of these habitats, and the species Artemisia tridentata ssp. tridentata 
(basin big sagebrush), Chrysothamnus nauseosus (grey rabbitbrush), 
Chrysothamnus viridiflorus (green rabbitbrush), Eriogonum strictum 
(strict buckwheat), Purshia tridentata (bitterbrush), and Tetradymium 
glabrata (little-leafed horsebrush) form a lesser component of the 
shrub community (Moseley 1994, p. 9; Mancuso and Moseley 1998, p. 17). 
Under relatively undisturbed conditions, the understory is populated by 
a diversity of perennial bunchgrasses and forbs, including species such 
as Achnatherum (formerly Oryzopsis) hymenoides (Indian ricegrass), 
Achillea millefolium (common yarrow), Phacelia heterophylla (varileaf 
phacelia), Astragalus purshii (Pursh's milkvetch), Phlox longifolia 
(longleaf phlox), and Aristida purpurea var. longiseta (purple 
threeawn) (Moseley 1994, p. 9; Mancuso and Moseley 1998, p. 17; Colket 
2005, pp. 2-3). Menke and Kaye (2006a, p. 1) describe high quality 
matrix habitat conditions for L. papilliferum as sagebrush-steppe 
habitat in late seral condition, and Fisher et al. (1996, p. 1) note 
that ``habitat with vigorous Lepidium populations has not been recently 
burned, is not heavily grazed, has an understory of native 
bunchgrasses, and a well developed microbiotic soil crust.'' Moseley 
(1994, p. 4) suggests that L. papilliferum serves as an indicator 
species for the health of the sagebrush-steppe ecosystem in the western 
Snake River Plain.
    The biological soil crust, also known as a microbiotic crust or 
cryptogamic crust, is one component of quality habitat for Lepidium 
papilliferum. Such crusts are commonly found in semiarid and arid 
ecosystems, and are formed by living organisms, primarily bryophytes, 
lichens, algae, and cyanobacteria, that bind together surface soil 
particles (Moseley 1994, p. 9; Johnston 1997, p. 4). Microbiotic crusts 
play an important role in stabilizing the soil and preventing erosion, 
increasing the availability of nitrogen and other nutrients in the 
soil, and regulating water infiltration and evaporation levels 
(Johnston 1997, pp. 8-10). In addition, an intact crust appears to aid 
in preventing the establishment of invasive plants (Brooks and Pyke 
2001, p. 4, and references therein; see also Serpe et al. 2006, pp. 
174, 176). These crusts are sensitive to disturbances that disrupt 
crust integrity, such as compression due to livestock trampling or off-
road-vehicle (ORV) use, and are also subject to damage by fire; 
recovery from disturbance is possible but occurs very slowly (Johnston 
1997, pp. 10-11).
    As described earlier, Lepidium papilliferum occurs in slickspot 
habitat microsites scattered within the greater semiarid sagebrush-
steppe ecosystem of southwestern Idaho. Lepidium papilliferum has 
infrequently been documented outside of slickspots, on occasion being 
found on disturbed soils, such as along graded roadsides and badger 
mounds. These are rare observations and the vast majority of plants 
documented over the past 19 years of surveys and monitoring for the 
species are documented within slickspot microsite habitats (USFWS 2006, 
p. 20). For example, in 2002, a complete census of an 11,070-ac (4,480-
ha) area recorded approximately 56,500 slickspots (U.S. Air Force, 
2003, p. 15), of which approximately 2,450 (about 4 percent) were 
occupied by L. papilliferum plants (Bashore, pers. comm. 2003, p. 1). 
Of the approximately 11,300 L. papilliferum plants documented during 
the survey effort, only 11 plants were documented outside of slickspots 
(U.S. Air Force 2002, in summary attachment of document).
    Slickspots are visually distinct openings characterized by soils 
with high sodium content and distinct clay layers; they tend to be 
highly reflective and relatively light in color, which makes them easy 
to detect on the landscape (Fisher et al. 1996, p. 3). Slickspots are 
distinguished from the surrounding sagebrush matrix as having the 
following characteristics: microsites where water pools when rain falls 
(Fisher et al. 1996, pp. 2, 4), sparse native vegetation, distinct soil 
layers with a columnar or prismatic structure, higher alkalinity and 
clay content and natric properties (Fisher et al. 1996, pp. 15-16; 
Meyer and Allen 2005, pp. 3-5, 8; Palazzo et al. 2008, p. 378), and 
reduced levels of organic matter and nutrients due to lower biomass 
production (Meyer and Quinney 1993, pp. 3, 6; Fisher et al. 1996, p. 
4). Fisher et al. (1996, p. 11) describe slickspots as having a 
``smooth, panlike surface'' that is structureless and slowly permeable 
when wet, moderately hard and cracked when dry. Although the low 
permeability of slickspots appears to help hold moisture (Moseley 1994, 
p. 8), once the thin crust dries, out the survival of L. papilliferum 
seedlings depends on the ability to extend the taproot into the 
argillic horizon (soil layer with high clay content), to extract 
moisture from the deeper natric zone (Fisher et al. 1996, p. 13).
    Slickspots have three primary layers: The surface silt layer, the 
restrictive layer, and an underlying moist clay layer. Although 
slickspots can appear homogeneous on the surface, the actual depth of 
the silt and restrictive layer can vary throughout the slickspot (Meyer 
and Allen 2005; Tables 9, 10, and 11). The top two layers (surface silt 
and restrictive) of slickspots are normally very thin; the surface silt 
layer varies in

[[Page 52019]]

thickness from 0.1 to 1.2 in (a few mm to 3 cm) in slickspots known to 
support Lepidium papilliferum, and the restrictive layer varies in 
thickness from 0.4 to 1.2 in (1 to 3 cm) (Meyer and Allen 2005, p. 3). 
The rangewide mean surface silt layer depth was 0.31 in (0.78 cm) based 
on a 2005 study of 769 slickspots of unknown occupancy sampled at 79 
transects (Colket 2006, p. 38). Additionally, measurements of the depth 
of the clay layer next to L. papilliferum plants at the Juniper Butte 
Training Range were taken in 2007 and 2008 to assess if depth of the 
clay layer could be a significant factor for plant germination. The 
average depth of the clay layer next to plants measured in 2007 was 2.5 
in (6.3 cm), with a range from 1.2 to 4.7 in (3.0 to 12.0 cm) (n=18), 
and in 2008 was 2.1 in (5.4 cm) with a range from 1.6 to 3.1 in (4.0 to 
8.0 cm) (n=16) (CH2MHill 2008a, p. 13). It appears that depth to the 
clay layer is not as critical to germination at the Juniper Butte 
Training Range as other factors may be (such as depth to surface of the 
soil, the timing and amount of moisture, seed bank, and ability of the 
slickspot to capture and maintain adequate moisture).
    It is not known how long slickspots take to form, but it is 
hypothesized to take several thousands of years (Nettleton and Peterson 
1983, p. 193; Seronko 2006). Climate conditions that allowed for the 
formation of slickspots in southwestern Idaho are thought to have 
occurred during a wetter Pleistocene period. Holocene additions of 
wind-carried salts (often loess deposits) produced the natric soils 
(high in sodium) characteristic of slickspots (Nettleton and Peterson 
1983, p. 191; Seronko 2006). It may take several hundred years to alter 
or lose slickspots through natural climate change or severe natural 
erosion (Seronko 2006). Some researchers hypothesize that, given 
current climatic conditions, new slickspots are no longer being created 
(Nettleton and Peterson 1983, pp. 166, 191, 206). As slickspots appear 
to have formed during the Pleistocene and new slickspots are not being 
formed, the loss of a slickspot is apparently a permanent loss.
    Some slickspots subjected to light disturbance in the past may 
apparently be capable of re-forming (Seronko 2006). Disturbances that 
alter the physical properties of the soil layers, however, such as deep 
disturbance and the addition of organic matter, may lead to destruction 
and permanent loss of slickspots. For example, such techniques as deep 
soil tilling, the addition of organic matter, and addition of gypsum 
have been recommended for the elimination of slickspots from 
agricultural lands in Idaho (Peterson 1919, p. 11; Rasmussen et al. 
1972, p. 142). Slickspot soils are especially susceptible to mechanical 
disturbances when wet (Rengasmy et al. 1984, p. 63; Seronko 2004). Such 
disturbances disrupt the soil layers important to Lepidium papilliferum 
seed germination and seedling growth, and alter hydrological function. 
Meyer and Allen (2005, p. 9) suggest that if sufficient time passes 
following the disturbance of slickspot soil layers, it is possible that 
the slickspot soil layers may regain their pre-disturbance 
configuration, yet not support the species. Thus, while the slickspot 
appears to have regained its former character, some essential component 
required to sustain the life history requirements of L. papilliferum 
has apparently been lost, or the active seed bank is no longer present.
    Most slickspots are between 10 square feet (ft\2\) and 20 ft\2\ (1 
square meter (m\2\) and 2 m\2\) in size, although some are as large as 
110 ft\2\ (10 m\2\) (Mancuso et al. 1998, p. 1). Slickspots cover a 
relatively small cumulative area within the larger sagebrush-steppe 
matrix, and only a small percentage of slickspots are known to be 
occupied by Lepidium papilliferum. For example, a 2002 inventory of the 
11,070 acre (ac) (4,480 hectare (ha)) Juniper Butte Range on the Owyhee 
Plateau found approximately 1 percent (109 ac (44 ha)) of the 
sagebrush-steppe area consisted of slickspot habitat, and of that 
slickspot habitat, only 4 percent (4 ac (1.6 ha)) was occupied by 
above-ground L. papilliferum plants (U.S. Air Force 2002, p. 9). It is 
not known why L. papilliferum is not found in a greater proportion of 
slickspot microsites (Fisher et al. 1996, p. 15).
    The highest monthly temperatures within the range of Lepidium 
papilliferum normally occur in July (approximately in the low 90 
degrees Fahrenheit (approximately 33 degrees Celsius)), and lowest 
monthly temperatures occur in January (approximately in the low 20 
degrees Fahrenheit (minus 7 degrees Celsius)). Precipitation tends to 
fall as rain, primarily in winter and spring (November to May); the 
lowest rainfall occurs in July and August, with the months of June, 
September, and October receiving slightly more rainfall than July and 
August. Average annual precipitation patterns vary within the species' 
range, and are generally higher in the northern regions (e.g., 11.7 in 
(29.7 cm) near Boise, 7.4 in (18.8 cm) at the city of Bruneau, and 9.9 
in (25.1 cm) at Mountain Home).
    Several analyses have shown a positive association between above-
ground abundance of Lepidium papilliferum and spring precipitation in 
the same year. Evaluating rangewide HII monitoring data collected over 
4 years from 1998 to 2001, Palazzo et al. (2005, p. 9) found a positive 
relationship (p-value less than 0.01) between abundance of above-ground 
plants and February to June precipitation. Meyer et al. (2005, p. 15) 
found that an increase in February through May precipitation increased 
the number of L. papilliferum seedlings at the OTA based on L. 
papilliferum census and survival data collected from 1993 to 1995. 
CH2MHill (2007a, p. 14) analyzed data from 2005 to 2007 collected at 
the Juniper Butte Range in the Owyhee Plateau region and found a 
positive correlation between spring precipitation and plant numbers. 
Utilizing HII monitoring data collected from 1998 to 2002, as well as 
2004 HIP monitoring data, Menke and Kay (2006a, b) found that March to 
May precipitation accounted for 99.4 percent of the variation in L. 
papilliferum abundance for the years 1998 to 2001 (2006a, p. 8), and 89 
percent for the years 1998 to 2002, and 2004 (2006b, pp. 10-11). These 
results appear to have been strongly influenced by the data point for 
1998, which was an unusually wet spring (Unnasch 2008, p. 16). Because 
the 1998 HII data represents an outlier with respect to both L. 
papilliferum abundance and precipitation, it largely determines the 
regression relationship by itself; thus, Menke and Kaye's 2006 
conclusion that abundance increases with spring precipitation is not 
well supported (Sullivan and Nations 2009, p. 140). More recently, 
however, Sullivan and Nations (2009, pp. 30, 41) analyzed data 
collected at the OTA over a period of 18 years between 1990 and 2008, 
and found evidence that both plant density at the rough census areas 
and plant abundance at special-use plots were positively related to 
mean monthly precipitation in late winter and spring (January through 
May). Thus, analysis of this long-term dataset again points to a strong 
relationship between L. papilliferum abundance and spring 
precipitation. This correlation of abundance with spring rainfall is 
important, as it at least partially explains annual fluctuations in L. 
papilliferum population numbers.
    In contrast, precipitation in the fall or early winter may have a 
negative effect on Lepidium papilliferum abundance the following spring 
(Meyer et al. 2005, p. 15; Sullivan and Nations 2009, p. 39). It has 
been suggested that this negative

[[Page 52020]]

relationship may be the result of prolonged flooding of the slickspot 
microsites, causing subsequent mortality of overwintering biennial 
rosettes (Meyer et al. 2005, pp. 15-16). This suggestion is supported 
by the analysis of 9 years of OTA data from the period 2000-2008 that 
shows a negative association between October to January precipitation 
and abundance of non-blooming L. papilliferum the following spring, 
although only the relationship with October to December precipitation 
is statistically significant (Sullivan and Nations 2009, p. 43). For 
blooming plants, the negative association between October to January 
precipitation and spring abundance was highly significant (Sullivan and 
Nations 2009, pp. 43-44).
    However, Unnasch (2008, p. 2) found no relationship between 
precipitation and the abundance of Lepidium papilliferum in an analysis 
of HIP data collected over a 3-year period from 2005 to 2007. Unnasch 
hypothesized that L. papilliferum may manifest threshold effects in 
germination and that there is a pulse of germination following a 
requisite amount of rainfall that could lead to a major flush of L. 
papilliferum germination during very wet years. If total rainfall is 
below that threshold, annual germination is more random (Unnasch 2008, 
p. 16). Comparing his results to those of Menke and Kaye, Unnasch 
(2008, p. 15) suggests that the relationship with spring precipitation 
reported by Menke and Kaye was strongly affected by abundance data from 
the year 1998, although in turn the relatively short 3-year study 
period may have influenced Unnasch's study results. Sullivan and 
Nations (2009, pp. 140, 142) likewise suggested that the exceptionally 
high precipitation in 1998 likely influenced the results of Menke and 
Kaye's analysis. However, as described above, Sullivan and Nation's 
more robust analysis of 18 years of data from the OTA confirmed a 
positive correlation between spring precipitation and the abundance of 
L. papilliferum (Sullivan and Nations 2009, pp. 40-44). As both annual 
precipitation and plant abundance are highly variable, the numbers of 
years included in the data set for evaluation is of great importance in 
determining the degree of confidence in the outcome of any statistical 
analysis. For this reason, the Service believes the Sullivan and 
Nations (2009, pp. 40-44) evaluation of the 18-year dataset from the 
OTA is the best available data regarding the relationship between 
precipitation and abundance of L. papilliferum.
    Recent analyses suggest that temperature also influences the annual 
abundance of Lepidium papilliferum. Although Menke and Kaye (2006b, p. 
8) found that minimum and maximum temperatures were not statistically 
correlated with L. papilliferum abundance based on a limited number of 
years of data, Sullivan and Nations (2009, p. 46-57) used more precise 
temperature data in concert with the 18-year L. papilliferum abundance 
dataset from the OTA to evaluate the potential interaction between 
precipitation, temperature, and plant abundance. Their analysis of the 
data collected between 1990 and 2008 suggests a complex relationship 
between temperature and precipitation that influences the abundance of 
L. papilliferum on an annual basis. In short, they found that 
temperature and precipitation interact during the months of October 
through January such that the lowest density or abundance of L. 
papilliferum in the spring follows a fall or early winter when both 
precipitation and temperature are low, or both are high. Spring plant 
density or abundance is greatest following a fall or early winter when 
either precipitation is high and temperature is low, or precipitation 
is low and temperature is high (Sullivan and Nations 2009, p. 56). 
During late winter and spring, analysis of one OTA dataset (the ``rough 
census'' areas) suggested that temperature had a negative impact on L. 
papilliferum density, such that density is greater when precipitation 
is high but temperatures during March through May are lower (Sullivan 
and Nations 2009, p. 47), whereas the model of the OTA special-use 
plots suggests only a positive interaction of L. papilliferum abundance 
with precipitation during this time period, with no temperature effect 
(Sullivan and Nations 2009, p. 47). Sullivan and Nations caution that 
the limited geographic area within which the interactions of 
precipitation and temperature were studied limits the ability to 
extrapolate the observed relationship beyond the bounds of the OTA 
(Sullivan and Nations 2009, p. 57).
    The sparse native vegetation naturally present at slickspots 
suggests that Lepidium papilliferum is more tolerant than surrounding 
vegetation at surviving in alkaline soils and spring inundation (e.g., 
Moseley 1994, p. 8, 14; Fisher et al. 1996, pp. 11, 16). Plant ecology 
literature suggests that plants tolerant of stress (e.g., plants that 
are capable of growing in harsh alkaline soils) are poor competitors 
(Grime 1977, p. 1185), making L. papilliferum a potentially poor 
competitor with other plants. In recent years, there are increasing 
observations of nonnative plants encroaching into slickspots, and 
consistent with theory, the evidence suggests that L. papilliferum is 
not able to successfully compete with these invasive exotics. Sullivan 
and Nations (2009, p. 111) report an ``apparent mutual exclusivity'' 
between nonnative plant species examined and L. papilliferum in 
slickspots. In other words, if plants such as Bassia prostrata 
(prostrate kochia or forage kochia, formerly Kochia prostrata) or 
Bromus tectorum are present in a slickspot, L. papilliferum is most 
often reduced in numbers or entirely absent.

Range and Distribution

    The range of Lepidium papilliferum is restricted to the volcanic 
plains of southwest Idaho, occurring primarily in the Snake River Plain 
and its adjacent northern foothills, with a single disjunct a 
population on the Owyhee Plateau (Figure 1). The plant occurs at 
elevations ranging from approximately 2,200 ft (670 m) to 5,400 ft 
(1,645 m) in Ada, Canyon, Gem, Elmore, Payette, and Owyhee Counties 
(Moseley 1994, pp. 3-9). Based on differences in topography, soil, and 
relative abundance, we have further divided the extant Lepidium 
papilliferum populations into three physiographic regions: the Boise 
Foothills, the Snake River Plain, and the Owyhee Plateau. The nature 
and severity of factors affecting the species also vary between the 
three physiographic regions for the purposes of analysis. For example, 
urban and rural development, agriculture, and infrastructure 
development has been substantial in the sagebrush-steppe habitat of the 
Boise Foothills and the Snake River Plain regions, while very little of 
these types of development has occurred within the Owyhee Plateau 
region. Genetic analyses reveal some separation between the greater 
Snake River Plain and Owyhee Plateau populations of L. papilliferum 
(Larson et al. 2006, p. 14), as might be expected due to their relative 
isolation. We are not aware of any studies that may have examined the 
relative genetic differentiation, if any, of the Boise Foothills 
population from the remainder of the Snake River Plain.
    Figure 1. Range of Lepidium papilliferum in southwest Idaho, 
showing its distribution in the three physiographic provinces of the 
Snake River Plain, Boise Foothills, and Owyhee Plateau.
BILLING CODE 4310-55-S

[[Page 52021]]

[GRAPHIC] [TIFF OMITTED] TR08OC09.000

BILLING CODE 4310-55-C
    As of February 2009, there were 80 extant EOs in the three 
physiographic regions that collectively comprise approximately 15,801 
ac (6,394 ha) of total area that is broadly occupied by Lepidium 
papilliferum (Cole 2009b, Threats Table). The area actually occupied by 
L. papilliferum is a small fraction of the total acreage, since 
slickspots occupy only a small percentage of the landscape, and L. 
papilliferum then occupies only a fraction of those slickspots (see 
U.S. Air Force 2002, p. 9, for an example). Table 1 presents the 
distribution and landownership and management information for all L. 
papilliferum EOs, in total and by region.

[[Page 52022]]



 Table 1. Distribution and Land Ownership of Lepidium papilliferum Element Occurrences by Physiographic Region (Cole 2009b, Threats Table; Sullivan and
                                                                  Nations 2009, p. 77).
                                           All areas are estimates, and may not total exactly due to rounding.
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                                                       Total EO Area
                                          Number of EOs       Federal ownership in    State ownership  in   Private ownership  in   (hectares)  [percent
     Lepidium papilliferum EOs         [percent of total]       acres  (hectares)      acres  (hectares)      acres  (hectares)      of total rangewide
                                                               [percent of total]      [percent of total]     [percent of total]          EO area]
--------------------------------------------------------------------------------------------------------------------------------------------------------
Snake River Plain                    43                      12,754 ac                55 ac                  164 ac                12,980 ac
                                     [54]..................  (5,160 ha)............   (22 ha).............   (66 ha).............  (5,250 ha)
                                                             [98]..................  [0.5]................  [1.5]................  [82]
--------------------------------------------------------------------------------------------------------------------------------------------------------
Boise Foothills                      16                      89 ac                   0 ac                   96 ac                  185 ac
                                     [20]..................  (36 ha)...............  (0 ha)...............  (39 ha)..............  (75 ha)
                                                             [48]..................  0....................  [52].................  [1.2]
--------------------------------------------------------------------------------------------------------------------------------------------------------
Owyhee Plateau                       21                      2,636 ac                 7 ac                  0 ac                   2,643 ac
                                     [26]..................  (1,067 ha)............  (3 ha)...............  (o ha)...............  (1,070 ha)
                                                             [99.7]................  [0.3]................  [0]..................  [16. 8%]
--------------------------------------------------------------------------------------------------------------------------------------------------------
All extant                           80                      15,479 ac               62 ac                  260 ac                 15,801 ac
EOs................................  [100].................  (6,264 ha)............  (25 ha)..............  (105 ha).............  (6,394 ha)
                                                             [98.0]................  [0.4]................  [1.6]................  [100]
--------------------------------------------------------------------------------------------------------------------------------------------------------

    The range of Lepidium papilliferum was first estimated in 1994 
(Moseley 1994, p. 6). Expanded survey efforts in recent years have 
resulted in an increase in the amount of known occupied habitat, 
particularly on the Owyhee Plateau and in the Boise Foothill regions. 
Between 2003 and 2006, 16 new EOs were documented, all within 3 mi (4.8 
km) of previously existing EOs: 2 on the Snake River Plain with a total 
area of 2.7 ac (1 ha), and 14 on the Owyhee Plateau with a total area 
of 46.6 ac (18 ha) (Colket et al. 2006, Tables and Appendix A). Since 
2006, additional surveys of previously unsurveyed lands have resulted 
in the discovery of several new occupied sites. Because most of these 
newly discovered sites were within 1 km (0.6 mi) of a documented EO, 
they typically resulted in the expansion or merging of existing EOs 
rather than the creation of a new EO. For example, in 2007, 2,560 ac 
(1,036 ha) of BLM land on the Owyhee Plateau were inventoried for L. 
papilliferum just south of the U.S. Air Force's Juniper Butte Training 
Range. Of the 2,171 slickspots surveyed, 200 (9 percent) were occupied 
by L. papilliferum with a total of 1,059 flowering plants and 214 
rosettes (ERO 2007, pp. 1, 7-8), resulting in the expansion of EO 16 
(Cole 2009a, p. 38). Surveys conducted in 2008 in the vicinity of the 
Ada County landfill in the Boise Foothills region revealed nearly 5,000 
plants in 75 slickspots (Cole 2008, p. 8), which expanded the size of 
existing EOs 38 and 65 (Cole 2009a, p. 39). Pre-development surveys 
conducted during 2007 by URS Corporation (URS) on BLM and private lands 
in the Boise Foothills region northwest of the City of Eagle detected 
43 occupied slickspots out of 187 surveyed, with approximately 17,880 
L. papilliferum plants (URS 2008, p. 10). These observations expanded 
the total area of EO 76 (Cole 2009a, p. 39). Finally, additional survey 
efforts on previously surveyed areas at the OTA resulted in the 
documentation of 365 new occupied slickspots in 2005, resulting in 
further expansion of existing EO 27 (URS 2005, pp. 6-7).
    Not all potential Lepidium papilliferum habitats in southwest Idaho 
have been surveyed, and it is possible that additional L. papilliferum 
sites may be found outside of areas that are currently known to be 
occupied. Recent modeling was completed to develop a high-quality, 
predictive-distribution model of L. papilliferum to identify potential 
habitat (Colket 2008, p. 1). Although surveys were conducted in 2008 in 
some areas identified as potential, previously unsurveyed habitat, 
these did not result in any new locations of the species (Colket 2008, 
pp. 4-6). There have also been searches for L. papilliferum in eastern 
Oregon, but the species has never been found there (Findley 2003, p. 
1). We have no historical records indicating that L. papilliferum has 
ever been found anywhere outside of its present range in southwestern 
Idaho, as described in this rule.

Abundance and Population Trend

    Forming a reliable estimate of any trend in the abundance of 
Lepidium papilliferum over time is complicated by multiple factors. For 
one, since individuals of the species may act as either an annual or a 
biennial, in any given year there will be varying numbers of plants 
acting as spring-flowering annuals versus overwintering rosettes. The 
relative proportions of these two life history forms can fluctuate 
annually depending on a variety of factors, including precipitation, 
temperature, and the abundance of rosettes produced the previous year 
(Unnasch 2008, pp. 14-15; Sullivan and Nations 2009, pp. 43-44, 134-
135). Secondly, L. papilliferum has a long-lived seed bank, likely as 
an adaptation to unpredictable conditions, in which years of good 
rainfall favorable for germination and survival may be followed by 
periods of drought; a persistent seed bank provides a population buffer 
against years of poor reproductive potential in such a highly variable 
environment (Meyer et al. 2005, p. 21). Only a small percentage of L. 
papilliferum seeds germinate annually, resulting in an estimated 
maximum longevity of 12 years for seeds in the seed bank (Meyer et al 
2005, p. 18). The presence of this persistent seed bank confounds the 
ability to determine any trend in abundance over time, as the number of 
above-ground plants that can be counted in any one year represents only 
a subset of the latent population that is present in the seed bank. In 
effect, it takes at least 12 years to trace the fate of a single year's 
cohort of seeds, resulting in a significant lag effect in detecting any 
real underlying change in total population abundance over the long 
term.
    An additional complicating factor in trying to detect any 
population trend for Lepidium papilliferum is the extreme

[[Page 52023]]

variability of annual abundance or density of the plant. As is common 
for desert annuals, the numbers of L. papilliferum can vary 
dramatically from year to year, depending on environmental conditions. 
As an example, the total number of plants on the 16 special-use plots 
at the OTA went from 624 individuals in 1997 to 3,330 plants in 1998, 
subsequently dropping back down again to 756 plants in 1999; total 
abundance over the years 1991 through 2008 ranged from a low of 249 
plants to 15,236 individuals (Weaver 2008). Some of the great variation 
in yearly plant numbers is likely due to the relationship between L. 
papilliferum and precipitation, as described above. The annual 
abundance or density of L. papilliferum shows a significant positive 
association with levels of spring rainfall, roughly from March through 
May (Meyer et al. 2005, p. 15; Palazzo et al. 2005, p. 9; Sullivan and 
Nations 2009, pp. 39-41), and survival of potential biennials is 
associated with increased summer rainfall (Meyer et al. 2005, p. 15). 
There is also some suggestion that increased winter precipitation may 
show a negative association with plant abundance, although not all 
analyses are consistently significant on this point (Meyer et al. 2005, 
pp. 15-16; Sullivan and Nations 2009, pp. 39-41). Temperature also 
appears to play a role in annual abundance of L. papilliferum in 
concert with precipitation, although the exact nature of the 
relationship is complex and not well understood (Sullivan and Nations 
2009, p. 57). Furthermore, the interaction between temperature, 
precipitation, and L. papilliferum abundance appears to vary regionally 
between the Boise Foothills, Owyhee Plateau, and Snake River Plain 
(Sullivan and Nations 2009, pp. 103-104).
    Because the population dynamics of Lepidium papilliferum are 
complicated, surrogate methods of monitoring the status of the species, 
such as monitoring the status of the ecosystem upon which it depends, 
may be preferable to counts of individual plants. For example, due to 
the extreme annual fluctuations in annual plant abundance and the 
complicating nature of the long-lived seed bank for this species, 
Mancuso and Moseley (1998, p. 1) note that ``estimating the number of 
above-ground plants is by itself not a reliable measure to evaluate 
population and species viability.'' As an alternative or supplement to 
population monitoring, they suggest monitoring the ecological integrity 
of L. papilliferum habitat, essentially using measures of habitat 
quality and quantity as a surrogate for assessing the status or 
viability of L papilliferum. Habitat monitoring is a recommended method 
of monitoring annual plants with a long-lived seed bank, where in some 
years the majority of the plant population is expressed in the seed 
bank rather than as above-ground plants (Elzinga et al. 1998, p. 55). 
For these reasons, we consider that data regarding the trends in 
habitat quality and quantity for L. papilliferum provide us with 
information that is equally important, if not more so, than direct 
counts of individual plants in evaluating the overall status of the 
species. Trends in habitat quality are discussed in the Habitat Quality 
section of this document, as well as under The Present or Threatened 
Destruction, Modification, or Curtailment of Its Habitat or Range in 
the Summary of Threats Affecting the Species section, below.
    From a statistical standpoint, the extreme variability in annual 
abundance or density estimates greatly reduces the ability to reliably 
detect a long-term trend in the population without many years of 
standardized data. The presence of the persistent seed bank adds 
further uncertainty to the determination of population trend, as 12 
years may effectively be considered to represent a single generation of 
the plant. Relatively short-term analyses of abundance estimates for 
the purposes of estimating a population trend are thus of limited 
utility due to the high variance observed in the data (Sullivan and 
Nations 2009, p. 93). In our evaluation, we weighed the relative 
quality of the available datasets for discerning population trend in 
Lepidium papilliferum according to the degree of confidence we had in 
the results of any analyses, given the great degree of variability 
observed and the multiple factors potentially influencing annual counts 
of the plant.
    Four data sets are available that provide some index or measure of 
Lepidium papilliferum abundance: Rangewide EO records, rangewide HII-
HIP transects, rough census data collected on the OTA, and special-use 
plot data from the OTA. Each of these programs is described in the 
Monitoring of Lepidium papilliferum Populations section, above, and the 
degree to which we relied on the information provided by them is 
described below.
    The INHP records of Lepidium papilliferum EOs provide only 
estimated ranges or categorical estimates of abundance, and are so 
variable in both size and space over time that we considered these 
records to be informative in terms of evaluating the current overall 
condition of the species, but we did not rely on EO records for 
temporal population trend estimates.
    Five years of HII monitoring data (1998 to 2002) and 5 years of HIP 
monitoring data (2004 to 2008) are available on Lepidium papilliferum 
abundance and habitat condition rangewide. Although the HII-HIP program 
provides valuable information regarding the relationship between L. 
papilliferum abundance and measures of habitat quality or disturbance, 
the time series of this data set is considered too short to reliably 
detect any trend in rangewide population abundance, due to the extreme 
annual variability in the data (Sullivan and Nations 2009, p. 93).
    We consider the best available data regarding Lepidium papilliferum 
abundance to be the long-term datasets from the OTA, including the 
rough census areas and special-use plots, which provide 18 years of 
population monitoring information. The relative value of the OTA 
dataset is supported by the analysis of Sullivan and Nations (2009), a 
report resulting from our contract with an independent consulting firm 
to evaluate the available population trend data for L. papilliferum, as 
well as to analyze any information available regarding potential 
relationships between the abundance of L. papilliferum and measures of 
habitat quality or disturbance. Considering the available data from the 
HII-HIP monitoring, and the rough census area and special-use plot 
monitoring from the OTA, Sullivan and Nations considered that the long-
term nature of the datasets from the OTA make these data the best 
available data when attempting to model trends through time (Sullivan 
and Nations 2009, p. 56). Furthermore, they placed slightly greater 
confidence in the analyses based on the rough census areas as opposed 
to the special-use plots, since the special-use plots are in effect a 
subset of the rough census areas and are based on counts from only a 
single slickspot, and are therefore subject to greater variability in 
response to localized impacts (Sullivan and Nations 2009, pp. 55, 96). 
They also noted that the HII and HIP programs do not yet have 
sufficient data to determine population trends rangewide (Sullivan and 
Nations (2009, p. 93). However, they determined that all three 
programs--rangewide HIP, OTA rough census areas, and OTA special-use 
plots-- track annual changes in L. papilliferum abundance similarly, 
and each can act as an index of abundance. Based on their analysis, 
they concluded that the trend observed on the OTA may be considered 
likely representative of

[[Page 52024]]

the trend across the entire range of the species (Sullivan and Nations 
2009, p. 96).

Analysis of Population Trend

    Sullivan and Nations analyzed the data on Lepidium papilliferum 
numbers (density or total abundance) from both the rough census areas 
and the special-use plots at the OTA, assuming a simple linear trend 
and using a repeated measures implementation of the general negative 
binomial regression model to account for the large variances in the 
data (a statistical technique for determining whether a statistically 
significant trend exists when using a data set with counts from the 
same areas every year and large changes in the values between years). 
The model was not intended to describe the complex pattern in the 
relative density or abundance of L. papilliferum over time, but only to 
determine whether there is evidence of any overall population trend 
(Sullivan and Nations 2009, p. 38).
    Based on this model, of the two OTA datasets, Sullivan and Nations 
(2009, pp. 3, 55, 96) considered the rough census data to be slightly 
more reliable. Their analysis of this rough census data showed a 
negative trend in density with a slope of -0.086 over the years 1990 to 
2008; this trend was statistically significant (p = 0.0087, two-sided 
p-value) (Sullivan and Nations 2009, pp. 38-39). Because plant density 
was unusually high on a single rough census area, the Study 4 Site, the 
data were reanalyzed, removing that site as a potentially highly 
influential data point. The result was a more shallow negative slope (-
0.059), but the trend remained statistically significant (p = 0.0046) 
(Sullivan and Nations 2009, p. 39).
    Rough census area densities were further regressed against 3-month 
running averages of precipitation. Lepidium papilliferum density was 
positively associated with mean monthly precipitation in each of the 
January to March, February to April, and March to May periods, and 
negatively associated with mean monthly precipitation for the periods 
October to December, November to January, and December to February; 
these relationships were all significant at p < 0.0001 (Sullivan and 
Nations 2009, pp. 39-40). These findings are consistent with those of 
Meyer et al. 2005 (pp. 15-16), which reported a positive association 
between Lepidium seedlings recruited and spring precipitation, and a 
likely negative association with winter precipitation, which is 
postulated to drown overwintering rosettes.
    The analysis of abundance data from the special-use plots on the 
OTA reveals a similarly negative slope over the years 1991 through 
2008, but the results were not statistically significant (p = 0.2857) 
(Sullivan and Nations 2009, p. 4). In other words, based on the count 
data from the special-use plots, there was not sufficient evidence to 
conclude that the slope of abundance over time was significantly 
different from zero. The relationship between abundance and spring 
precipitation on the special-use plots was similar to that observed on 
the rough census areas; mean monthly precipitation in January to March, 
February to April, and March to May were all positively associated with 
abundance and all were statistically significant (p < 0.0001). There 
was no significant relationship, however, between fall or winter 
precipitation and Lepidium papilliferum abundance on the special-use 
plots (Sullivan and Nations 2009, p. 41). Using a shorter time-series 
of data from 2000 to 2008, Sullivan and Nations (2009, pp. 43-44) found 
that the abundance of blooming plants was positively associated with 
both the current year's precipitation and the number of rosettes 
present in the previous year, and that the number of rosettes was 
negatively associated with precipitation in the prior October to 
December period.
    The researchers concluded that there is ``limited evidence for 
declining populations,'' because trends on the OTA are negative but 
only statistically significant for the rough census areas (Sullivan and 
Nations 2009, pp. 2, 44). In earlier analyses of Lepidium papilliferum 
population HII-HIP data, Menke and Kaye had initially reported a 
negative rangewide population trend for the periods 1998 through 2002 
(Menke and Kaye 2006a) and for 1998 through 2004 (Menke and Kaye 
2006b). However, Sullivan and Nations (2009, p. 141) point out that the 
fact that the HII transects were first monitored during a higher-than-
average abundance year in 1998 greatly influenced the interpretation of 
the short time-series dataset, and suggest that the negative trend in 
abundance is not supported when abundance in subsequent years is 
included. Additionally, as described above, the HII-HIP data collection 
has not yet occurred over a long enough period to allow for reliable 
trend analyses (Sullivan and Nations 2009, p. 93). In comparing the 
mean number of L. papilliferum per transect resulting from his own 
analyses of HIP data from 2005 through 2007 with the results reported 
by Menke and Kaye (2006b), Unnasch (2008, p. 14) suggests that, since 
1999, there has been no consistent rangewide population trend for the 
species.
    Although Sullivan and Nations did not attempt to discern a trend in 
population numbers based on the HIP data, they did compare mean total 
abundance of Lepidium papilliferum per transect between physiographic 
regions, based on the HIP data from 2004 through 2008. They found that 
relative abundance was significantly different between regions, being 
greatest in the Boise Foothills region and lowest on the Owyhee Plateau 
region; abundance on the Snake River Plain region was intermediate 
between the other two (Sullivan and Nations 2009, p. 103).
    In summary, we have reviewed all of the best available scientific 
and commercial data available to us to determine whether we can discern 
a long-term trend in the abundance of Lepidium papilliferum. The 
extreme variability in annual counts of the species makes it difficult 
to discern a trend in numbers with statistical confidence. For this 
reason, we place greater confidence in the longest time series of 
monitoring data available to us, that from the OTA (up to 18 years of 
data for some rough census areas and all special-use plots). In 
addition, as described above, Sullivan and Nations suggest that the 
data from the rough census areas may be considered slightly more 
reliable than that from the special-use plots (Sullivan and Nations 
2009, pp. 3, 55). The long-term data from the OTA, which we considered 
to be the best available data for attempting to model trends through 
time in agreement with Sullivan and Nations (2009, pp. 3, 56), suggest 
that population numbers may be trending downward on the OTA. Although 
numbers on both the rough census areas and the special-use plots showed 
a slightly negative slope over time, only the analysis of the rough 
census areas was statistically significant (Sullivan and Nations 2009, 
pp. 38-40). We considered this to be relatively limited evidence of a 
downward trend in the population, given the lack of consistently 
significant results between the two monitoring programs. Furthermore, 
the slope is not steep, annual variation in plant numbers continues to 
be extremely high, and the plant has demonstrated an ability to rebound 
from low numbers due to the persistent seed bank.
    We do recognize, however, that the OTA provides some of the highest 
quality habitat remaining for Lepidium papilliferum. Therefore, we 
believe it is reasonable to infer that if the population is trending 
downward there, then conditions are likely worse in the

[[Page 52025]]

remainder of the plant's range where habitat conditions are more 
degraded. This conclusion is supported by the analysis of Sullivan and 
Nations (2009, p. 96), which suggests that the trends on the OTA, as a 
general index of abundance, might reasonably be considered 
representative of trends rangewide (Sullivan and Nations 2009, p. 96). 
Direct evidence in support of this argument, however, is lacking. In 
addition, since the abundance of L. papilliferum is associated with 
annual precipitation, we considered whether any trend in precipitation 
over the same time period for which the rough census areas and special-
use plot data were collected might be correlated with the observed 
negative trend in plant numbers. Assuming a simple linear trend, 
analogous to the model used by Sullivan and Nations in their analysis 
of L. papilliferum density and abundance at the OTA over time, we found 
no significant trend in precipitation at the OTA over the years 1991 
through 2007 (data were not available for 2008). Although we evaluated 
total annual precipitation, total and mean winter precipitation, total 
and mean spring precipitation, and 3-month moving averages across the 
year, least squares regression did not yield any slopes of 
precipitation over time that were statistically significant from zero 
(Zwartjes 2009, p. 1). Any observed negative trend in L. papilliferum 
density or abundance at the OTA thus appears to be independent of any 
trend in precipitation over the time period of interest.
    In weighing all of this information, we conclude that the best 
available evidence suggests that Lepidium papilliferum numbers may be 
trending downward. The dataset from the rough census areas on the OTA 
shows a significant downward trend in density over the last 18 years. 
Furthermore, we believe it is reasonable to infer that this negative 
trend may be similar or possibly even greater rangewide in areas 
outside the high quality habitat of the OTA, and this trend appears to 
be independent of any trend in precipitation. The best available 
scientific and commercial data therefore suggest that over the past two 
decades, L. papilliferum has likely significantly declined in 
abundance.
    In terms of projecting this trend into the future, however, there 
are many uncertainties associated with both the data and the model that 
preclude our ability to do so; these include, but are not limited to: 
Great annual variability in plant numbers, the confounding influence of 
the long-lived seed bank, the complications associated with annual 
variability in both precipitation and temperature, and the inconsistent 
results between the special-use plots and the rough census areas on the 
OTA. The evaluation of Sullivan and Nations was based on a simple model 
of Lepidium papilliferum abundance or density as a linear function of 
time, and intended only to discern whether there was any general trend 
in the population. The authors acknowledge that the dynamics are 
complicated, and note their model is not intended to describe (nor 
explain) the details of the temporal pattern of abundance or density of 
L. papilliferum (Sullivan and Nations 2009, p. 38). In addition, we do 
not have any models for L. papilliferum based on multivariate analyses, 
which would simultaneously take into account additional variables such 
as precipitation, to potentially allow for the prediction of abundance 
or density of L. papilliferum over time based on projected conditions. 
Although the currently available model is helpful in terms of 
interpreting the population information available to date and indicates 
that L. papilliferum has likely been trending downward, for all of the 
reasons outlined above, it would be inappropriate to rely on this model 
to predict any future population trajectory for L. papilliferum.

Habitat Quality

    As described above under ``Ecology and Habitat,'' the natural 
sagebrush-steppe community that surrounds the slickspot microsites in 
which Lepidium papilliferum occurs is dominated by sagebrush (primarily 
Artemisia tridentata ssp. wyomingensis) with a diverse understory of 
native perennial bunchgrasses and forbs. Historically, fires were 
relatively infrequent in this ecosystem, likely occurring on the order 
of every 100 years (Whisenant 1990, p. 4). Data on the plant community 
and fire history pattern are some of the habitat quality attributes 
collected as part of Lepidium papilliferum HIP monitoring, which has 
been conducted rangewide since 2004. Results from the 2008 HIP 
monitoring conducted at 80 HIP transects indicated that over the past 5 
years, 14 of the transects (18 percent) that were initially 
characterized by predominantly native vegetation have undergone overall 
declines in habitat quality, primarily due to increased nonnative 
species cover (Colket 2009, pp. 10). Furthermore, this increase in 
nonnatives was observed not only in the surrounding plant community, 
but in the slickspots occupied by L. papilliferum as well. Bromus 
tectorum was the most common nonnative species in slickspots, followed 
by Agropyron cristatum (crested wheatgrass), Ceratocephala testiculata, 
formerly Ranunculus testiculatus (bur buttercup), and Lepidium 
perfoliatum (clasping-leaf pepperweed) (ICDC 2008, p. 9). Noxious or 
aggressive nonnatives detected in HIP transect slickspots include Linum 
perenne (`Appar' blue flax), Centaurea cyanus (garden cornflower), 
Bassia prostrata (prostrate kochia or forage kochia), Chondrilla juncea 
(rush skeletonweed), and Cardaria draba (whitetop) (Colket 2009, pp. 8-
9).
    A review of the rangewide HIP transect data for evidence of fire 
history reveals that 38 of 80 HIP transects (48 percent) currently show 
no effects from wildfire and 6 others (7.5 percent) were predominantly 
unburned. Five transects (6.25 percent) had partially burned (with 
approximately half of the area unburned), 13 (16.25 percent) were 
predominantly burned, and 18 (22.5 percent) have completely burned 
(Colket 2009, Table 5). HIP classifies areas as burned if they are 
devoid of shrub cover or have patchy shrub cover in areas that exhibit 
the site capacity to support a healthy sagebrush-steppe community; this 
may include areas that have recently or historically burned. Four HIP 
transects were burned in 2007 in the Murphy Complex Fire in the Owyhee 
Plateau geographic region (Colket 2009, p. 23). Sixty-six of the 80 HIP 
transects (83 percent) have nearby wildfire effects within 1,640 ft 
(500 m) (Colket 2009, p. 26). A recent geospatial data analysis 
evaluating the total Lepidium papilliferum EO area affected by wildfire 
from 1957 to 2007 found that the perimeter of 107 wildfires that had 
occurred encompassed approximately 11,442 ac (4,509 ha), or 73 percent 
of the total EO area rangewide (Stoner 2009, p. 48). However, caution 
should be used in interpreting this geospatial information, as this 
represents relatively coarse vegetation information that may not 
reflect that some EOs may be located within remnant unburned islands of 
sagebrush habitat within fire perimeters.
    Several features of slickspots and their surrounding habitat were 
consistently more degraded in areas that had burned. Slickspots in 
burned areas had lower soil crust cover and greater exotic (nonnative) 
species cover, and the total native species cover and shrub cover were 
consistently lower in burned transects, while total exotic species 
cover,, including Bromus tectorum, was consistently higher in burned 
transects (Menke and Kaye 2006b, p. 19). Sullivan and Nations (2009, p. 
3) found a significantly negative relationship

[[Page 52026]]

between the abundance or density of Lepidium papilliferum and both the 
presence of B. tectorum and past fire. The positive association between 
the abundance of B. tectorum and fire frequency is well established 
(Whisenant 1990, p. 6). The complex and positive feedback loop between 
the encroachment of invasive annual grasses such as B. tectorum, 
increased fire frequency, and decreased integrity of biological soil 
crusts contributes to the degradation of sagebrush-steppe habitat 
quality for L. papilliferum (for additional details, see the Modified 
Wildfire Regime and Invasive Nonnative Plant Species discussions under 
Factor A of Summary of Factors Affecting the Species).

Element Occurrences Rangewide

    The EO ranking system utilized by the INHP is described above in 
the Monitoring of Lepidium papilliferum Populations section. In brief, 
occurrences of Lepidium papilliferum are ranked based on measures of 
habitat quality and species abundance. The first EO ranks for L. 
papilliferum were assigned in 1993 (Colket et al. 2006, Tables 1-13). 
In 2006, L. papilliferum EO specifications and ranking were updated and 
revised by the ICDC to apply more consistent EO specifications 
rangewide (Colket et al. 2006, pp. 15-44). Due to the change in methods 
in 2006, EO rankings assigned before 2006 are not comparable to those 
assigned after 2006. Currently, EO ranks are more consistently 
assigned, are useful as an assessment of estimated viability or 
probability of persistence, and help prioritize conservation planning 
or actions (NatureServe 2002).
    As of February 2009, the INHP has ranked 80 extant EO records for 
Lepidium papilliferum based on habitat quality and abundance (Cole 
2009b, Threats Table). In addition, nine EOs are ranked as extirpated 
or probably extirpated, and seven EOs are considered historical 
(information is too vague for relocation of the sites). All nine 
extirpations were formerly verified locations from old herbarium 
collections (the most recent from 1955) where the habitat is now 
completely developed or converted to agricultural lands (Colket et al. 
2006, Table 13). The 80 extant (as of February 2009) EOs represent a 
reduction in the number of extant EOs (85) known in 2006. However, this 
reduction in the number of EOs is due to the merging of EOs associated 
with new locations of plants rather than from the loss of individual 
EOs. As of February 2009, there are no A-ranked EOs for L. 
papilliferum; the most common EO ranks for L. papilliferum rangewide 
are C and D (Table 2). EO ranks also vary by physiographic region. A 
little more than one-half of the extant EO area in the Boise Foothills 
region is ranked as C, which means there are 50 to 399 above-ground 
plants, low to moderate introduced nonnative plant species cover, and 
EOs are partially burned. Approximately three-quarters of the total EO 
area in the Snake River Plain is ranked B, meaning there are 400 to 999 
above-ground plants, the native plant community is intact with low 
introduced nonnative plant species cover, and EOs are largely unburned. 
The majority of the B-ranked EO acreage rangewide occurs on the Idaho 
Army National Guard's Orchard Training Area (OTA). The majority of the 
total EO area in the Owyhee Plateau physiographic region is also ranked 
B.
    EO size can also influence the ranking of an EO as a percentage of 
total rangewide EO area. For example, one EO (number 27) located on the 
OTA in the Snake River Plain region has a total area of 7,163 acres 
(2,899 ha) and accounts for roughly 59 percent of all the area within 
Lepidium papilliferum EOs assigned a B rank throughout the entire range 
of the species. There are less than 2.2 ac (1 ha) of B-ranked area in 
the Boise Foothills region, and nearly 2,540 B-ranked ac (1,028 ha) on 
the Owyhee Plateau. Therefore, according to the EO rankings, the 
majority of the highest quality remaining habitat for L. papilliferum 
occurs on the Snake River Plain (see Table 2), with most of that 
occurring within the OTA.

                             Table 2. Extant Element Occurrence (EO) Ranks across the entire range of Lepidium papilliferum
                                                             (INHP data from February 2009).
--------------------------------------------------------------------------------------------------------------------------------------------------------
           Element Occurrence Rank                        No. EO's                     Hectares                  Acres               Percent of Area
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                     Boise Foothills
--------------------------------------------------------------------------------------------------------------------------------------------------------
B                                             1                                                   0.84                     2.07                     1.65
--------------------------------------------------------------------------------------------------------------------------------------------------------
BC                                            1                                                   1.79                     4.41                     3.53
--------------------------------------------------------------------------------------------------------------------------------------------------------
C                                             5                                                  28.34                    70.03                    56.05
--------------------------------------------------------------------------------------------------------------------------------------------------------
D                                             6                                                  15.37                    37.99                    30.40
--------------------------------------------------------------------------------------------------------------------------------------------------------
F                                             3                                                   4.23                    10.46                     8.37
--------------------------------------------------------------------------------------------------------------------------------------------------------
TOTAL                                         16                                                 50.57                   124.96                   100.00
--------------------------------------------------------------------------------------------------------------------------------------------------------
 
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                    Snake River Plain
--------------------------------------------------------------------------------------------------------------------------------------------------------
B                                             5                                               3,875.14                 9,575.47                    73.77
--------------------------------------------------------------------------------------------------------------------------------------------------------
BC                                            1                                                   1.42                     3.51                     0.03
--------------------------------------------------------------------------------------------------------------------------------------------------------
C                                             19                                                935.06                 2,310.53                    17.80
--------------------------------------------------------------------------------------------------------------------------------------------------------
D                                             12                                                350.44                   865.94                     6.67
--------------------------------------------------------------------------------------------------------------------------------------------------------
D?                                            1                                                   0.78                     1.93                     0.01
--------------------------------------------------------------------------------------------------------------------------------------------------------

[[Page 52027]]

 
F                                             4                                                  89.82                   221.94                     1.71
--------------------------------------------------------------------------------------------------------------------------------------------------------
NR                                            1                                                   0.20                     0.48                     0.00
--------------------------------------------------------------------------------------------------------------------------------------------------------
TOTAL                                         43                                              5,252.86                12,979.81                   100.00
--------------------------------------------------------------------------------------------------------------------------------------------------------
 
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                   Owyhee Plateau \1\
--------------------------------------------------------------------------------------------------------------------------------------------------------
B                                             5                                               1,027.50                 2,537.00                    96.02
--------------------------------------------------------------------------------------------------------------------------------------------------------
C                                             4                                                  21.85                    53.99                     2.04
--------------------------------------------------------------------------------------------------------------------------------------------------------
D                                             5                                                  18.42                    45.52                     1.72
--------------------------------------------------------------------------------------------------------------------------------------------------------
E                                             0                                                   0.00                     0.00                     0.00
--------------------------------------------------------------------------------------------------------------------------------------------------------
F                                             7                                                   2.36                     5.83                     0.22
--------------------------------------------------------------------------------------------------------------------------------------------------------
TOTAL                                         21                                               1070.13                 2,644.35                   100.00
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Note that Sullivan and Nations (2009, pp. 79-81) differed in their overview of extant EOs in the Owyhee Plateau as they presented EO 16 as each of
  its 27 individual sub-EOs (sub-EOs 700-726). Table 2 combines all Owyhee Plateau sub-EOs into the single EO 16 and also incorporates changes as
  described in the February 2009 INHP Lepidium papilliferum data.

Summary of Factors Affecting the Species

    Section 4 of the Act and its implementing regulations (50 CFR 424) 
set forth the procedures for adding species to the Federal Lists of 
Endangered and Threatened Wildlife and Plants. A species may be 
determined to be an endangered or threatened species due to one or more 
of the five factors described in section 4(a)(1) of the Act: (A) The 
present or threatened destruction, modification, or curtailment of its 
habitat or range; (B) overutilization for commercial, recreational, 
scientific, or educational purposes; (C) disease or predation; (D) the 
inadequacy of existing regulatory mechanisms; or (E) other natural or 
manmade factors affecting its continued existence. Listing actions may 
be warranted based on any of the above threat factors, singly or in 
combination. Each of these factors relevant to Lepidium papilliferum is 
discussed below.
A. The Present or Threatened Destruction, Modification, or Curtailment 
of Its Habitat or Range
    Several threat factors are contributing to the destruction, 
modification, or curtailment of Lepidium papilliferum's habitat or 
range. The sagebrush-steppe habitat of the Great Basin where L. 
papilliferum occurs is becoming increasingly degraded due to the 
impacts of multiple threats, including the invasion of nonnative annual 
grasses, such as Bromus tectorum, and increased frequency of fire. As 
described below, B. tectorum can impact L. papilliferum directly 
through competition, but also indirectly by providing continuous fine 
fuels that contribute to the increased frequency and extent of 
wildfires. Frequent wildfires have numerous negative consequences in 
the sagebrush-steppe system, which is adapted to much longer fire-
return intervals, ultimately resulting in the conversion of the 
sagebrush community to nonnative annual grasslands, with associated 
losses of native species diversity and natural ecological function. 
Because the modified wildfire regime and invasion of B. tectorum create 
a positive feedback loop, it is difficult to separate out the effects 
of each of these threat factors independently. We have attempted to do 
so here, but much of the discussion may overlap due to the inherent 
synergism between these two threat factors.
    In addition to wildfire and nonnative plants, development poses a 
threat to Lepidium papilliferum, both directly through the destruction 
of populations and loss of slickspot microsites, and indirectly through 
habitat fragmentation and isolation (discussed separately under Factor 
E, below). The loss of slickspots is a permanent loss of habitat for L. 
papilliferum, since the species is specialized to occupy these unique 
microsite habitats that were formed in the Pleistocene, and once lost, 
slickspots cannot be recreated on the landscape.
    Livestock pose a threat to Lepidium papilliferum, primarily through 
mechanical damage to individual plants and slickspot habitats. However, 
the current livestock management conditions and associated conservation 
measures address this potential threat such that it does not pose a 
significant risk to the viability of the species as a whole.
    All of these threats have long been recognized as contributing to 
the ongoing degradation of the sagebrush-steppe ecosystem of 
southwestern Idaho. However, we have only recently received independent 
evaluations of the direct relationship between the more significant 
threats and indicators of population viability specifically for 
Lepidium papilliferum. New evidence suggests that there is a 
significant negative association between cover of nonnative plant 
species and wildfire and the abundance of L. papilliferum, such that 
the species appears to be in decline across its range, with adverse 
impacts continuing and likely increasing into the foreseeable future. 
Each of the threat factors contributing to the present or threatened 
destruction, modification, or curtailment of L. papilliferum's habitat 
or range is assessed in detail below.

Modified Wildfire Regime

    Fire was historically infrequent in the desert shrublands of the 
Great Basin, as

[[Page 52028]]

the native plant communities of the native annuals and bunchgrasses did 
not provide sufficient fine fuels to carry large scale wildfires. The 
bare spaces between widely spaced shrubs and relatively low fuel loads 
in such ecosystems as the sagebrush-steppe generally prevented fires 
from spreading very far, and any fires that did burn were usually 
restricted to relatively small, isolated patches (Brookes and Pyke 
2001, p. 5; Whisenant 1990, pp. 4, 6). Natural fire return intervals in 
sagebrush-steppe prior to the arrival of European settlers are 
estimated to have ranged from 60 to 110 years; the estimate for the 
more xeric Artemisia tridentata ssp. wyomingensis sagebrush community 
inhabited by Lepidium papilliferum is estimated to have been as long as 
100 years (Wright and Bailey 1982, p. 158) and possibly up to 240 years 
(Baker 2006, p. 181). Beginning in the early 1900s, however, the 
widespread invasion of nonnative plant species, particularly annual 
grasses such as Bromus tectorum and Taeniatherum caput-medusae, has 
created a bed of continuous fine fuels across the southwest Idaho 
landscape. The continuous fine fuels provided by these nonnative annual 
grasses result in more frequent fires due to greater horizontal fuel 
continuity, increased fuel surface-to-volume ratio, and various 
properties that facilitate wildfire ignition, such as lower moisture 
content and thus increased flammability (Whisenant 1990, p. 6; Pellant 
1996, p. 3 and references therein; Brooks et al. 2004a, p. 679). 
Nonnative annual grasses also provide for more continuous and uniform 
fires, burning across extensive areas of the landscape. Native 
bunchgrasses provide a patchy, discontinuous fuelbed such that fires 
are not easily carried and tend to burn only in small patches. The 
continuous fires carried by nonnative annual grasses such as B. 
tectorum, on the other hand, leave few or no patches of unburned 
vegetation, which can inhibit the post-fire recovery of native 
sagebrush-steppe vegetation by eliminating seed sources for regrowth of 
the native species (Whisenant 1990, p. 4; Pyke 2007). Bromus tectorum, 
in particular, apparently alters the soil environment such that it 
creates a positive feedback loop, enhancing the environment for its own 
growth and generating conditions conducive to further invasion (Pyke 
2007). As B. tectorum has become more dominant in the sagebrush-steppe 
habitat of the Snake River Plain over the past several decades, 
wildfire frequency intervals have become shortened from the historical 
average of 60 to 110 years to the current frequency intervals of 5 
years or less (Wright and Bailey 1982, p. 158; Billings 1990, pp. 307-
308; Whisenant 1990, p. 4; USGS 1999; West and Young 2000, p. 262; 
Launchbaugh et al. 2008, p. 3; Zouhar et al. 2008, pp. 40-41).
    The dramatic increase in the frequency of wildfires has a 
particularly negative effect on the native plant community in this 
region that has historically experienced fire relatively infrequently, 
and thus is dominated by plants that are not adapted to short fire-
return intervals. Many of the native species of the sagebrush-steppe 
ecosystem are killed outright by wildfires and do not have adaptations 
such as underground rhizomes for post-fire vegetative regrowth, but 
must reproduce by seed. As a result, under a regime of increasingly 
frequent fire, perennial plants tend to be lost from the landscape 
(Whisenant 1990, p. 9). Sagebrush (Artemisia spp.), for example, are 
easily killed by fire (Baker 2006, p. 178 and references therein; 
Cooper et al. 2007, p. 8; USDA Forest Service Fire Effects Information 
System 2009). Because they are not adapted to frequent fires, sagebrush 
does not resprout after burning, as many fire tolerant species do 
(Young and Evans 1978, pp. 283, 287; Brooks and Pyke 2001, pp. 6-7; 
USDA Forest Service Fire Effects Information System 2009), but must 
rely upon seed sources for reestablishment. Natural revegetation 
requires a nearby remnant seed source, as from an unburned patch of 
sagebrush, which now rarely occurs because of the more continuous and 
extensive fires that occur if a B. tectorum understory is present (USDA 
Forest Service Fire Effects Information System 2009). In addition, when 
fires occur as frequently as every 3 to 5 years, even if seedlings 
should begin to grow there is not sufficient time for sagebrush to 
regenerate prior to the next fire cycle. Thus, sagebrush is eliminated 
from the plant community, which in turn allows for conversion to annual 
grassland (Whisenant 1990, p. 9; Pyke 2007; USDA Forest Service Fire 
Effects Information System 2009). The short fire-return intervals now 
experienced in this region prevent the sagebrush-steppe community from 
recovering and attaining late seral stage condition, thus eliminating 
high quality habitat for L. papilliferum.
    The dramatic increase in frequency and extent of wildfires has 
contributed to the conversion of vast areas of sagebrush-steppe into 
invasive annual grasslands (USGS 1999). Since post-fire conditions are 
favorable for further invasion and establishment of nonnative annual 
grasses, invasive grasses soon dominate the community, leading to the 
establishment of an invasive grass-increased fire frequency cycle 
(Whisenant 1990, p. 4; Brooks and Pyke 2001, p. 5; D'Antonio and 
Vitousek 1992, pp. 73, 75; Brooks et al. 2004a, p. 678). Invasive 
grasses promote recurrent fires, which in turn convert high diversity 
native shrublands to low diversity alien grasslands; these grasslands 
then burn more frequently and expansively across the landscape, 
creating disturbance conditions that promote the further expansion of 
the invasive grasses, and so on. This invasive grass-fire cycle has 
been recognized in Great Basin shrub ecosystems since the 1930s (Brooks 
and Pyke 2001, p. 5, and references therein). As an example, at the 
Snake River Birds of Prey National Conservation Area in the Snake River 
Plain area of southern Idaho, nearly half of the native sagebrush-
steppe habitat (a total of 494,211 ac (200,000 ha)) converted to 
nonnative annual grasslands in less than 10 years by a series of 200 
fires (Smith and Collopy 1998, as cited in Brooks and Pyke 2001, p. 7).
    The rate of conversion from sagebrush-steppe to annual grasslands 
continues to accelerate in the Snake River Plain of southwest Idaho 
(Whisenant 1990, p. 4). As the coverage of Bromus tectorum continues to 
increase in the region, it is reasonable to expect that the extent and 
frequency of wildfires will likewise continue to increase, given the 
demonstrated positive feedback cycle between these factors (Whisenant 
1990, p. 4; Brooks and Pyke 2001, p. 5; D'Antonio and Vitousek 1992, 
pp. 73, 75; Brooks et al. 2004a, p. 678). Climate change models also 
project a likely increase in fire frequency within the semiarid Great 
Basin region inhabited by Lepidium papilliferum (see Climate Change 
under Factor E, below).
    Wildfire therefore contributes to the continuing invasion and 
establishment of nonnative annual grasslands within the range of 
Lepidium papilliferum, which in turn further increases the likelihood 
of more frequent and intense wildfires across the range of the species 
(Brooks et al. 2004a, pp. 677-687). But wildfire's role in promoting 
the invasion of annual grasses goes beyond its circular positive impact 
on the fire cycle, as nonnative annual grasses and other nonnative 
plant species that are likely to invade following fire have numerous 
other negative effects on L. papilliferum, slickspots, and the 
surrounding sagebrush-steppe ecosystem as well, as described below 
under Invasive Nonnative Plant Species.

[[Page 52029]]

    Wildfire also damages biological soil crusts, which are important 
to the sagebrush-steppe ecosystem and slickspots where Lepidium 
papilliferum occur, because the soil crusts stabilize and protect soil 
surfaces from wind and water erosion, retain soil moisture, discourage 
annual weed growth, and fix atmospheric nitrogen (Eldridge and Greene 
1994 as cited in Belnap et al. 2001, p. 4; Johnston 1997, pp. 8-10; 
Brooks and Pyke 2001, p. 4). Fires can cause severe damage to soil 
crusts, altering their ecological function and creating an opportunity 
for invasion by weedy annual plant species (Johnston 1997, p. 10; 
Brooks and Pyke 2001, p. 4, and references therein). In a statistical 
analysis of HII and HIP data between 1998 and 2004, burned areas had 
less soil crust cover and higher nonnative plant cover (Menke and Kaye 
2006b, p. 3). In general, L. papilliferum abundance is greatest in 
areas that also have the greatest cover of soil crust (Boise Foothills 
and Snake River Plain), although the populations in the Owyhee Plateau 
contrasted in showing a slightly negative (but not statistically 
significant) relationship with soil crust cover (Sullivan and Nations 
2009, p. 135). Fire in the presence of shrubs, particularly sagebrush, 
tends to be greater in intensity, which decreases the potential for 
soil crust recovery (Johnston 1997, p. 11); therefore, recovery of 
these crusts after a fire is less likely in the sagebrush-steppe 
habitat where L. papilliferum occurs. Given the generally positive 
association between soil crust cover and L. papilliferum, the 
compromised integrity of the microbiotic crust in response to fire 
likely has a negative impact on L. papilliferum as well.
    More frequent wildfires also promote soil erosion and consequent 
sedimentation, as perennial grasses that normally limit erosion are 
eliminated in arid environments such as the sagebrush-steppe ecosystem 
(Bunting et al. 2003, p. 82). Increased sedimentation can result in a 
silt layer that is too thick for optimal Lepidium papilliferum 
germination (Meyer and Allen 2005, pp. 6-7). Wind erosion following 
wildfire can also remove the top silt layer of slickspots, exposing the 
clay vesicular layer below, as observed at HIP transect 721 following 
the 2007 Murphy Complex Fire (U.S. BLM 2007, p. 23). However, effects 
of the loss of the upper slickspot silt layer on L. papilliferum are 
not known.
    The threats of wildfire and nonnative invasive species working in 
concert are considered the predominant factor affecting Lepidium 
papilliferum, particularly its habitat quality. In a statistical 
analysis of HII data over 5 years between 1998 and 2001, areas that had 
burned earlier in the study and were left with depleted shrub and soil 
crust did not recover (Menke and Kaye 2006a, p. iii). Burned areas had 
less native plant cover, greater nonnative plant cover, increased 
slickspot perimeter compromise (the slickspot boundaries lose 
definition), and increased organic debris accumulation (Menke and Kaye 
2006a, p. iii). As mentioned above, analysis of additional HII and HIP 
data from 1998 through 2004 showed that burned areas had less soil 
crust cover and greater nonnative plant cover (Menke and Kaye 2006b, p. 
3). Past wildfires thus appear to have had a lasting negative impact on 
the plant community surrounding slickspots, including increased 
nonnative species cover and decreased soil crust cover (Menke and Kaye 
2006b, p. 19). Although we recognized wildfire as one of the primary 
threats affecting the matrix habitat of L. papilliferum in our 2007 
finding, at that time we did not have any data that directly tied 
wildfire with a negative impact on the species itself, as would be 
demonstrated, for example, by a corresponding decline in L. 
papilliferum abundance (72 FR 1622, 1635; January 12, 2007).
    As discussed above, several researchers have noted signs of 
increased habitat degradation for Lepidium papilliferum, most notably 
in terms of exotic species cover and wildfire frequency (e.g., Moseley 
1994, p. 23; Menke and Kaye 2006b, p. 19; Colket 2008, pp. 33-34), but 
only recently have analyses demonstrated a statistically significant 
negative relationship between the degradation of habitat quality, both 
within slickspot microsites and in the surrounding sagebrush-steppe 
matrix, and the abundance of L. papilliferum. Sullivan and Nations 
(2009, pp. 114-118, 137) found a consistent, statistically significant 
negative correlation between wildfire and the abundance of L. 
papilliferum across its range. Their analysis of 5 years of HIP 
monitoring data indicated that L. papilliferum ``abundance was lower 
within those slickspot (sic) that had previously burned'' (Sullivan and 
Nations 2009, p. 137), and the relationship between L. papilliferum 
abundance and fire is reported as ``relatively large and statistically 
significant,'' regardless of the age of the fire or the number of past 
fires (Sullivan and Nations 2009, p. 118). The nature of this 
relationship was not affected by the number of fires that may have 
occurred in the past; whether only one fire had occurred or several, 
the association with decreased abundance of L. papilliferum was similar 
(Sullivan and Nations 2009, p. 118).
    The evidence also points to an increase in the geographic extent of 
wildfire within the range of Lepidium papilliferum. Since the 1980s, 59 
percent of the total L. papilliferum management area acreage rangewide 
has burned, more than double the acreage burned in the preceding three 
decades (from the 1950s through 1970s). Based on available information, 
approximately 11 percent of the total management area burned in the 
1950s; 1 percent in the 1960s; 15 percent in the 1970s; 26 percent in 
the 1980s; 34 percent in the 1990s; and as of 2007, 11 percent in the 
2000s (data based on GIS fire data provided by BLM Boise and Twin Falls 
District; I. Ross 2008, pers. comm. and A. Webb 2008, pers. comm., as 
cited in Colket 2008, p. 33). Based on the negative relationship 
observed between fire, L. papilliferum, and habitat quality as 
described above, we conclude that this increase in area burned 
translates into an increase in the number of L. papilliferum 
populations subjected to the negative impacts of wildfire.
    An evaluation of Lepidium papilliferum EOs for which habitat 
information has been documented (79 of 80 EOs) demonstrates that most 
have experienced the effects of fire. Fifty-five of 79 EOs have been at 
least partially burned (14 of 16 EOs on the Boise Foothills, 30 of 42 
EOs on the Snake River Plain and 11 of 21 EOs on the Owyhee Plateau), 
and 75 EOs have adjacent landscapes that have at least partially burned 
(16 of 16 EOs on the Boise Foothills, 39 of 42 EOs on the Snake River 
Plain, and 20 of 21 EOs on the Owyhee Plateau) (Cole 2009b, Threats 
Table).
    In 2008, 38 of the 80 HIP transects were unburned, 6 were 
predominantly unburned, 5 approximately half burned and half unburned, 
13 were predominantly burned, and 18 were completely burned. Sixty-six 
HIP transects had been at least partially burned to within 1,500 ft 
(500 m) (Colket 2009, p. 26). In 2007, the Inside Desert Fire on the 
Owyhee Plateau burned 2,695 ac (1,041 ha) within Management Area 11, 
and the Elk Mountain Fire burned 11,868 ac (4,083 ha) within Management 
Area 11; both fires were part of the 652,016 ac (263,862 ha) Murphy 
Complex Fire in the Owyhee Plateau region (Colket 2009, p. 65). In 
2008, the first year of HIP monitoring following the fire was completed 
in the four transects (Transects 701, 711, 719, and 721) that burned in 
the Murphy Complex Fire

[[Page 52030]]

(Colket 2009, p. 24). All 10 slickspots at HIP transect 701 had been 
previously burned before being burned again in 2007. At HIP transect 
711, only 1 slickspot had been previously burned, but 9 of its 10 
slickspots were burned in the Murphy Complex Fire. HIP transects 719 
and 721 were completely unburned high quality big sagebrush habitat 
before the Murphy Complex Fire burned all 10 slickspots at both HIP 
transects (Colket 2009, p. 24).
    A 2009 geospatial data analysis evaluating the total Lepidium 
papilliferum EO area affected by wildfire from 1957 to 2007 found that 
107 wildfires have occurred, the fire perimeters of which included 
approximately 11,442 ac (4,509 ha), or 73 percent of the total EO area 
(Stoner 2009, p. 48).
    Table 3 shows the evidence of wildfires documented through HIP 
rangewide transect monitoring in 2008 and includes both recent and 
historical fires. Wildfire evidence can remain on the landscape for up 
to 20 years.

      Table 3. Evidence of Wildfire Documented at HIP Transects in 2008 (Colket 2009, Table 5, pp. 50-62).
----------------------------------------------------------------------------------------------------------------
                                                                                                   Adjacent
                                                                                              landscapes  within
                                     Number of HIP       Number of HIP                          0.31 miles (500
     Physiogeographic Region      transects at least     transects not         Total HIP        meters) of HIP
                                   partially burned         burned             transects       transects either
                                                                                                   burned or
                                                                                               partially burned
----------------------------------------------------------------------------------------------------------------
Boise Foothills                   7                   3                   10                  10
----------------------------------------------------------------------------------------------------------------
Snake River Plain                 21                  26                  47                  38
----------------------------------------------------------------------------------------------------------------
Owyhee Plateau                    14                  9                   23                  19
----------------------------------------------------------------------------------------------------------------
TOTAL                             42 (52.5 percent)   38 (47.5 percent)   80 (100 percent)    67 (84 percent)
----------------------------------------------------------------------------------------------------------------

    The effects of fire disturbance and habitat degradation are evident 
in some of the earliest photographs of HII and HIP transects, which 
show habitats lacking shrubs and dominated by Bromus tectorum. However, 
photographs from the early 1990s of transects that had not burned prior 
to being established were comprised primarily of native Artemisia 
tridentata with a nonnative B. tectorum or Ceratocephala testiculata 
understory. As of 2008, 14 of 80 total HIP transects had changed from a 
higher to a lower habitat quality classification since 2004, or had 
been partially or completely burned (Colket 2009, pp. 8-9). The 
photographs demonstrate that many of the transects that burned are now 
devoid of A. tridentata and are instead dominated by B. tectorum 
(Colket 2009, pp. 63-64).
    At present, ongoing control efforts may slow the incidence of 
wildfire in some areas, but are not capable of preventing wildfires 
across the range of Lepidium papilliferum. For example, four 
established HIP transects on the Owyhee Plateau burned in 2007 in the 
Inside Desert and Murphy Complex fires, even though wildfire control 
measures were in place and implemented (Colket 2009, p. 24). In the 
Snake River Plain region, portions of two EOs (EO 32, EO 26) were 
burned in 2006 by the Ten York Fire and Cold Fire respectively. No EOs 
or portions of known EOs are documented to have burned in the Snake 
River Plain and Boise Foothills regions in 2007 (U.S. BLM 2008a, p. 
21). On the OTA, the IDARNG has demonstrated intensive management 
efforts implemented to suppress wildfire and using wildfire-
rehabilitation activities with minimal ground disturbance have been 
effective in reducing the threat of wildfire and the rate of spread of 
nonnative invasive species (for additional information, see Wildfire 
Management and Post-Wildfire Rehabilitation section below). However, 
such intensive management is currently concentrated within L. 
papilliferum EOs and is possible only within a limited range of L. 
papilliferum. This may explain why the highest quality habitat 
remaining is on the OTA, where the greatest infrastructure is in place 
to manage and control wildfires.
Summary of Modified Wildfire Regime
    The observed increases in frequency and geographic extent of 
wildfires, the negative consequences for L. papilliferum and its 
habitat associated with the invasion of nonnative grasses and wildfire, 
the strong positive feedback loop between wildfire and conversion of 
sagebrush-steppe to annual grasslands, and the lack of effective 
rangewide control mechanisms all contribute to the current modified 
wildfire regime being the greatest ongoing threat to L. papilliferum's 
existence. In addition, the best available data indicates that fire 
frequency is likely to increase in the foreseeable future due to 
increases in cover of B. tectorum and the projected effects of climate 
change (see Invasive Nonnative Plant Species, below, and also Climate 
Change under Factor E, below). Ongoing habitat loss and degradation is 
a result of the current wildfire regime, which is interrelated with 
several other negative factors, including: Increased nonnative species 
cover, especially annual grasses; increased sedimentation and organic 
debris accumulation in slickspots, which could alter slickspot function 
and hinder germination of L. papilliferum; the loss of native matrix 
vegetation, particularly shrubs; decreased native plant species 
diversity; decreased cover of microbiotic crusts; and habitat 
fragmentation due to isolation of habitat patches following fire.
    Given the observed negative association between the abundance of 
Lepidium papilliferum and the increased frequency of fire, as well as 
the demonstrated negative impacts of frequent fire on the components 
that normally provide high quality habitat for L. papilliferum, such as 
late seral stage sagebrush and high microbiotic crust cover, we 
consider the current wildfire regime to pose a significant threat to L. 
papilliferum. Recurrent fire promotes the continued invasion of 
nonnative annual grasses and other invasive nonnative plants, along 
with all of their associated negative effects (see Invasive Nonnative 
Plant Species below). Based on the observed increases in the cover of 
Bromus tectorum throughout the range of the species, the lack of 
effective control mechanisms, and projections under most climate change 
models, we expect the degree of this threat will continue and likely 
increase within the foreseeable future. The significant threat posed by 
the current modified wildfire regime is pervasive throughout the range 
of the species.

[[Page 52031]]

Invasive Nonnative Plant Species

    Invasive nonnative plants have become established in Lepidium 
papilliferum habitats by spreading through natural dispersal (unseeded) 
or have been intentionally planted as part of revegetation projects 
(seeded). Invasive nonnative plants can alter multiple attributes of 
ecosystems, including geomorphology, wildfire regime, hydrology, 
microclimate, nutrient cycling, and productivity (Dukes and Mooney 
2003, pp. 1-35). They can also negatively affect native plants through 
competitive exclusion, niche displacement, hybridization, and 
competition for pollinators; examples are widespread among native taxa 
and ecosystems (D'Antonio and Vitousek 1992, pp. 63-87; Olson 1999, p. 
5; Mooney and Cleland 2001, p. 1). Geospatial analyses indicate that 
approximately 20 percent of the total area of all L. papilliferum EOs 
rangewide is dominated by introduced invasive annual and perennial 
plant species (Stoner 2009, p. 81), and monitoring of HIP transects 
rangewide indicates that nonnative plant cover is continuing to 
increase at a relatively rapid pace (Colket 2008, pp. 1, 3). Although, 
historically, disturbance of native communities tended to pave the way 
for invasion by nonnative plants, today nonnative annual plants such as 
Bromus tectorum are so widespread that they have been documented 
spreading into areas not impacted by disturbance (Piemeisel 1951, p. 
71; Tisdale et al. 1965, pp. 349-351; Stohlgren et al. 1999, p. 45). 
The known impacts of nonnative plants on L. papilliferum are discussed 
in this section.
    One of the characteristics of slickspots is that they are largely 
devoid of native shrubs, grasses, and forbs, with the exception of 
Lepidium papilliferum; this is one of the features that make slickspots 
relatively easy to detect on the landscape (Moseley 1994, pp. 8, 14; 
Fisher et al. 1996, pp. 3-4, 11; Colket 2008, p. 1). Lepidium 
papilliferum has adapted to the unique edaphic and hydrological (soil 
and water) properties of the slickspot microsites that it inhabits, and 
has thus evolved with little competition from other native plants 
(Moseley 1994, p. 14). Weedy, nonnative plants have begun to invade 
these slickspots, however, including Agropyron cristatum, Bromus 
tectorum, Lepidium perfoliatum, Ceratocephala testiculata, and, in some 
areas, Bassia prostrata (Colket 2009, p. 3; Fisher et al. 1996, p. 4; 
Sullivan and Nations 2009, p. 99).
    In our January 12, 2007, finding (72 FR 1622), we recognized 
invasive nonnative plants as one of the primary factors degrading the 
quality of L. papilliferum's habitat, but at the time we had no 
evidence demonstrating any negative association between the presence of 
nonnative plant species and either the abundance of L. papilliferum 
itself or the proportion of L. papilliferum in flower. For example, 
Menke and Kaye (2006b, p. 15) originally reported no correlation 
between the abundance of L. papilliferum and weedy species cover, 
either within slickspots or in the surrounding matrix vegetation. 
However, more recent analyses of the additional years of data now 
available have revealed a significant negative association between the 
presence of weedy species and the abundance or density of L. 
papilliferum, to the point that L. papilliferum may be excluded from 
slickspots (Sullivan and Nations 2009, pp. 109-112). Although the 
specific mechanisms are not well understood, some of these plants, such 
as A. cristatum and B. tectorum, are strong competitors in this arid 
environment for such limited resources as moisture, which tends to be 
concentrated in slickspots (Pyke and Archer 1991, p. 4; Moseley 1994, 
p. 8; Lesica and DeLuca 1998, p. 4), at least in the subsurface soils 
(Fisher et al. 1996, pp. 13-16). The available information, detailed 
below, indicates that nonnative plants in both slickspots and the 
surrounding matrix vegetation are negatively affecting L. papilliferum. 
Furthermore, we now have additional evidence that areas occupied by L. 
papilliferum formerly dominated by native vegetation are experiencing 
relatively rapid increases in cover of nonnative plant species; for 
example, Colket (2008, pp. 1, 3) reports that 22 of the 80 HIP 
transects (28 percent) have shown increases in nonnative plant species 
cover of 5 percent or more over the last 4 to 5 years. Here we discuss 
the effects of nonnative plant species on L. papilliferum and its 
habitat, detailing the evidence related to unseeded and seeded 
nonnative plants separately.
Unseeded Nonnative Invasive Plants
    The most common unseeded nonnative annual grasses known to occur in 
Lepidium papilliferum's habitat include Bromus tectorum and 
Taeniatherum caput-medusae. Annual nonnative forbs now commonly 
associated with slickspots include Lepidium perfoliatum, Salsola kali 
(tumbleweed, also known as Russian thistle), Sisymbrium altissimum 
(tumble mustard, also known as tall tumble mustard), and Ceratocephala 
testiculata (Colket 2009, pp. 8-9).
    As discussed under Modified Wildfire Regime above, Bromus tectorum 
in particular has become dominant in many sagebrush-steppe habitat 
areas during the last century due to livestock grazing, agriculture, 
and wildfire impacts (Pickford 1932, p. 165; Piemeisel 1951, p. 71; 
Peters and Bunting 1994, p. 34; Vail 1994, pp. 3-4; Brooks and Pyke 
2001, pp. 4-6). Vast areas of sagebrush shrublands have been converted 
to B. tectorum in the past century (about 31,000 mi\2\ (80,000 km\2\) 
in the Great Basin alone) (Menakis et al. 2003, p. 284). Low-elevation 
sites, which are relatively dry and experience wide variation in soil 
moisture, appear to be more vulnerable to B. tectorum invasion than 
higher elevation sites with more stable soil moisture. Bromus tectorum 
plants tend to be larger and more fecund in a post-wildfire environment 
than on unburned sites, potentially leading to subsequent increases in 
density on burned sites under favorable climatic conditions (Zouhar 
2003a, as summarized in Zouhar et al. 2008, p. 154). The invasion of 
nonnative plant species, particularly annual grasses, has had a greater 
effect on the lower elevation sagebrush shrublands in the Snake River 
Plain of Idaho that historically experienced less frequent fire than 
higher elevation sites in the region; the higher elevation sites have 
higher precipitation and historically had more fine grasses and more 
frequent wildfires (Gruell 1985, pp. 103-104; Peters and Bunting 1994, 
p. 33). These lower elevation sagebrush shrublands include the range of 
Lepidium papilliferum. As detailed under Modified Wildfire Regime, 
above, the B. tectorum-fire cycle modifies and degrades the native 
sagebrush-steppe ecosystems on which L. papilliferum depends, and 
recurrent fire prevents the system from achieving the late seral stage 
condition that characterizes high-quality habitat for the species.
    In addition to perpetuating the cycle of increased wildfire within 
the range of Lepidium papilliferum, nonnative plants such as Bromus 
tectorum and Taeniatherum caput-medusae can have additional negative 
impacts on L. papilliferum through competition, displacement, and 
altering the ecological function of slickspots. Invasive grasses can 
replace native plants such as L. papilliferum by outcompeting them for 
resources, such as soil nutrients or moisture (Brooks and Pyke 2001, p. 
6, and references therein). Bromus tectorum in particular appears to 
displace native plants by prolific seed production, early germination, 
and superior competitive abilities for the

[[Page 52032]]

extraction of water and nutrients (Pellant 1996, pp. 3-4; Pyke 2007). 
In addition, B. tectorum is capable of modifying the ecosystems by 
altering the soil temperatures and soil water distribution (Pellant 
1996, p. 4). Evidence that B. tectorum is likely displacing L. 
papilliferum is provided by Sullivan and Nations' (2009, p. 135) 
statistical analyses of L. papilliferum abundance and nonnative 
invasive plant species cover within slickspots. Working with 5 years of 
HIP data collected from 2004 through 2008, Sullivan and Nations found 
that the presence of other plants in slickspots, particularly invasive 
exotics such as Bassia prostrata and Bromus tectorum, was associated 
with the almost complete exclusion of L. papilliferum from those 
microsites (Sullivan and Nations 2009, pp. 111-112). Of all the factors 
considered in their analysis, only the amount of B. tectorum in the 
plant community around slickspots showed a consistent relationship with 
the abundance of L. papilliferum across all three physiographic regions 
comprising the range of the species, and in all cases this relationship 
was significantly negative (Sullivan and Nations 2009, pp. 131, 136-
137).
    In addition to the roughly 3.3 million ac (1.3 million ha) of 
public lands in the Great Basin already dominated by Bromus tectorum 
(translating to about 5,156 mi\2\ or 13,354 km\2\), Pellant (1996, p. 
1, and references therein) identifies another 76.1 million ac (30.8 
million ha, or 119,000 mi\2\ (308,210 km\2\)) either infested with this 
nonnative grass or susceptible to invasion by the species, and suggests 
that the spread of B. tectorum could increase in the future due to its 
adaptability, including the presence of multiple genotypes.
    The dominance of Bromus tectorum in an area may also be positively 
related to the density of Owyhee harvester ants (Pogonomyrmex salinus), 
which represent an emerging threat to Lepidium papilliferum. The 
replacement of sagebrush by annual grasses, such as B. tectorum, 
apparently creates conditions favorable to nesting of the native 
harvester ant, leading to expanded range and density of this 
potentially important seed predator of L. papilliferum. The invasion of 
B. tectorum and other nonnative annual grasses may thus exacerbate the 
threat posed by seed predation (see Factor C, Disease or Predation, 
below, for details).
    Bradley and Mustard (2006, p. 1146) found that the best indicator 
for predicting future invasions of Bromus tectorum was the proximity to 
current populations of the grass. Colket (2009, pp. 37-49) reports that 
52 of 80 HIP transects (65 percent) had B. tectorum cover of 0.5 
percent or greater within slickspots in at least 1 year between 2004 
and 2008; nearly 95 percent of slickspots had some B. tectorum present. 
If current proximity to B. tectorum is an indicator of the likelihood 
of future invasion by that nonnative species, then Lepidium 
papilliferum is highly vulnerable to future invasion by B. tectorum 
throughout its range. If the invasion of B. tectorum continues at the 
rate witnessed over the last century, an area far in excess of the 
total range occupied by L. papilliferum could be converted to nonnative 
annual grasslands within the foreseeable future. First introduced 
around 1889 (Mack 1981, p. 152), B. tectorum cover in the Great Basin 
is now estimated at approximately 30,888 mi\2\ (80,000 km\2\) (Menakis 
et al. 2003, p. 284), translating into an historical invasion rate of 
approximately 257 mi\2\ (666 km\2\) a year over 120 years. If the 
spread of B. tectorum continues at even half of that rate, an area 
equal in size to the 2,250 mi\2\ (5,800 km\2\) range of L. papilliferum 
would be invaded by B. tectorum in less than 20 years. In addition, 
climate change models for the Great Basin region also predict climatic 
conditions that will favor the growth and further spread of B. tectorum 
(see Factor E, Climate Change, below).
    There is increasing evidence that nonnative plants are invading 
formerly sparsely vegetated slickspots (Moseley 1994, p. 14), and the 
presence of these nonnative plants within slickspots is negatively 
associated with the abundance of Lepidium papilliferum (Sullivan and 
Nations 2009, pp. 109-113). Although Menke and Kaye (2006b, p. 15) 
found no significant correlation between weedy species cover and either 
abundance of L. papilliferum or proportion of L. papilliferum in flower 
based on a single year of observations (2004), Sullivan and Nations' 
(2009, p. 135) statistical analyses of plant abundance and nonnative 
invasive plant species cover within slickspots (based on 5 years of HIP 
data from 2004 through 2008) indicated that L. papilliferum abundance 
decreased with increased Bromus tectorum cover in the Boise Foothills 
and the Snake River Plain at statistically significant levels. There 
was no relationship evident on the Owyhee Plateau; however, the authors 
note that there is little B. tectorum in the slickspots in that region. 
Therefore, the nature of any relationship in that region would be 
difficult to detect (Sullivan and Nations 2009, p. 135). Although B. 
tectorum is not yet invading slickspots to a great extent in the Owyhee 
Plateau region, its increasing presence across the landscape is 
indicative of degraded L. papilliferum habitat (Sullivan and Nations 
2009, pp. 136-137). Similarly, survey sites on the Owyhee Plateau from 
2000 through 2002 with ``abundant'' weeds (referred to as unseeded 
nonnative plants) had 26 percent fewer total L. papilliferum plants 
when compared to the least-weedy sites, and more rosettes than 
flowering plants, indicating proportionally fewer flowering L. 
papilliferum plants (Popovich 2009, p. 26).
    Another nonnative annual grass, Taeniatherum caput-medusae, 
overlaps in both distribution and habitat requirements with Bromus 
tectorum. Introduced in the late 1880s, the subsequent rapid spread of 
T. caput-medusae, has caused serious management concerns in the Great 
Basin because of its vigorous competitive nature and ability to 
transform native shrub and perennial grass ecosystems to annual grass 
monocultures, much like B. tectorum (USDA Forest Service Fire Effects 
Information System 2009).. Taeniatherum caput-medusae cover increases 
and rapidly spreads under frequent fires at the expense of native 
species, and may even replace B. tectorum (Hironaka 1994, pp. 89-90; 
Brooks and Pyke 2001, p. 5; USDA Forest Service Fire Effects 
Information System 2009). Taeniatherum caput-medusae is unpalatable to 
livestock and has low forage value. When dry, the dead T. caput-medusae 
vegetation decomposes slowly and forms a persistent dense litter on the 
soil surface. Similar to B. tectorum, accumulated T. caput-medusae 
litter enables stand-replacement fires to occur in ecosystems that are 
not adapted to frequent fire (Brooks and Pyke 2001, p. 5; Norton et al. 
2007, pp. 2-3; Hironaka 1994, pp. 89-90). Wildfires in T. caput-
medusae-infested areas usually minimally damage soil surfaces and soil 
erosion is limited, but enough T. caput-medusae seeds typically survive 
to produce thin, vigorous stands of T. caput-medusae plants the 
following year. Within a few years, stand densities approach pre-fire 
levels, perpetuating the modified wildfire regime (Hironaka 1994, pp. 
89-90; Brooks and Pyke 2001, p. 5; Norton et al. 2007, pp. 2-3; 
Chambers 2008, p. 53). As with B. tectorum, T. caput-medusae continues 
to expand its range in association with increased fire frequency (USDA 
Forest Service Fire Effects Information System 2009).

[[Page 52033]]

    Other nonnative invasive species in sagebrush-steppe habitats have 
the ability to displace native plant species, such as Lepidium 
papilliferum. For example, Chondrilla juncea (rush skeletonweed) is an 
unseeded, nonnative, invasive, perennial plant found in some HIP 
transect slickspots (Colket 2009, p. 8). In 2008, C. juncea was 
observed during native plant surveys in the Boise Foothills to be 
widespread and occurring in small, low-density stands (Cole 2008, p. 
13). Ongoing recreation-related soil disturbance from pedestrians and 
cyclists will likely encourage C. juncea invasion into L. papilliferum 
sites (Cole 2008, p. 13). Chondrilla juncea moves into new areas 
primarily through wind-transported seed dispersal and root fragment 
transport, but persists and expands primarily through bud formation on 
root systems of established plants (Kinter et al. 2007, p. 393; USFS 
2009). Disturbance to aboveground C. juncea plants stimulates formation 
of root buds, making this invasive plant difficult to control, and 
potentially allowing this nonnative invasive plant to displace L. 
papilliferum.
    Examining the presence of Bassia prostrata, Bromus tectorum, 
Agropyron cristatum, total seeded nonnative plants, total unseeded 
nonnative plants, and biological crust cover, Sullivan and Nations 
(2009, p. 109) concluded that ``near mutual exclusivity of these plants 
(excepting biological crust) and slickspot peppergrass is a dominant 
pattern.'' Although, historically, few species other than L. 
papilliferum were found in slickspots, nonnative plant species now 
appear to be displacing L. papilliferum from its specialized slickspot 
microsite habitats. The results from 2008 HIP monitoring revealed that 
all 80 HIP transects (10 transects on the Boise Foothills, 48 transects 
on the Snake River Plain and 22 transects on the Owyhee Plateau) 
monitored within 54 EOs had some nonnative, unseeded plant cover 
(Colket 2009, Table 4, pp. 37-49). Within some transects, the amount of 
nonnative plant cover within slickspots was high. For example, within 
the Boise Foothills, 1 of 10 HIP transects had 85 percent nonnative 
plant cover and 1 of 10 transects had nonnative plant cover between 25 
and 50 percent of the transect. On the Snake River Plain, 2 of 48 
transects had nonnative plant cover between 25 and 50 percent of the 
transect. Unseeded nonnative invasive plant cover was lowest in the 
Owyhee Plateau, where none of the 22 HIP transects had unseeded 
nonnative invasive plant cover greater than 10 percent (Colket 2009, 
Table 4, pp. 37-49). At this point, a minority of transects has a high 
degree of nonnative plant cover. The evidence indicates, however, that 
the degree of nonnative plant cover is increasing, and can do so at a 
relatively rapid rate (because Colket (2008, pp. 1-3) reported 
increases in nonnative plant species cover of 5 percent or more over 
the span of 4 to 5 years in 28 percent of the HIP transects formerly 
dominated by native plant species).
    Existing conservation measures designed to reduce the potential 
adverse effects of nonnative, unseeded species are addressed in three 
conservation documents (CCA, U.S. Air Force Integrated Natural Resource 
Management Plan (INRMP), and IDARNG INRMP) that apply to approximately 
98 percent of Lepidium papilliferum's occupied range. The CCA includes 
conservation measures designed to protect remnant blocks of native 
vegetation, prioritize weed control measures at L. papilliferum EOs, 
develop and implement protective weed control techniques, describe 
revegetation requirements for disturbed areas, educate the public on 
nonnative species and their spread, use vehicle wash points and 
stations, and support research and funding for nonnative species 
control (State of Idaho et al. 2006, pp. 131-132). The military also 
has a number of ongoing efforts to suppress nonnative species on U.S. 
Air Force and IDARNG managed lands. All military vehicles entering the 
IDARNG's OTA from areas more than 50 mi (80.4 km) away are washed at a 
high-pressure wash-rack facility to prevent weed seed introduction. 
Small patches of noxious weeds are hand-pulled when they are found by 
IDARNG staff, and other larger noxious weed sites on the OTA are 
reported annually to BLM for treatment (IDARNG 2004, p. 67). The U.S. 
Air Force tries to reduce the impacts of exotic annual species by 
reseeding disturbed areas with native vegetation to the maximum extent 
practicable, eradicating noxious weeds prior to their spreading, and 
requiring the cleaning of U.S. Air Force vehicles and equipment on a 
wash rack upon return to the base. The U.S. Air Force avoids the use of 
pesticides within 25 ft (8 m) of slickspots and uses pesticides only if 
wind conditions are favorable (directed away from the slickspot) to 
prevent the loss of L. papilliferum (U.S. Air Force 2004, pp. R-4, R-
5). While these efforts are beneficial, their effectiveness is limited 
by the challenge of controlling or eliminating invasive nonnative 
plants from all the sagebrush-steppe ecosystems where L. papilliferum 
occurs, due to the sheer magnitude of the problem, logistical and 
budgetary limitations, and the still-evolving methodology for restoring 
these ecosystems to their natural condition (Bunting et al. 2003, p. 
82; Pyke 2007).
Seeded Nonnative Invasive Plants
    Rangeland revegetation projects on public lands in southwest Idaho 
have included providing forage for livestock, controlling erosion, 
preventing wildfires, reducing nonnative annual grass density, and 
rehabilitating watersheds. To meet these revegetation objectives, land 
managers often plant nonnative species, which can outcompete native 
species and result in decreased biodiversity (summarized by Harrison et 
al. 1996; Beyers 2004, p. 953). For example, Agropyron cristatum, a 
forage species that was once commonly planted in revegetation projects 
within the range of Lepidium papilliferum, is a strong competitor, and 
its seedlings are better than some native species at acquiring moisture 
at low temperatures (Pyke and Archer 1991, p. 4; Lesica and DeLuca 
1998, p. 1; Bunting et al. 2003, p. 82). We now know that when A. 
cristatum is present in a slickspot, L. papilliferum tends to be few in 
numbers or absent altogether (Sullivan and Nations 2009, p. 109), 
indicating that A. cristatum is likely displacing L. papilliferum. 
Thinopyrum intermedium (intermediate wheatgrass, formerly Agropyron 
intermedium) has also been seeded in some southern Idaho rangeland 
areas, including the Owyhee Plateau region, where it is found in L. 
papilliferum sites on U.S. Air Force (CH2MHill 2008a, p. 5) and BLM 
lands (ERO Resources Corporation 2008, p. 10; Colket 2009, pp. 37-49). 
One long-term research study (73 years) conducted in Utah, Idaho, and 
Nevada found that once established, T. intermedium and Bromus inermis 
(smooth brome) dominate a site and suppress not only other herbaceous 
species, but also Artemisia spp. and Purshia tridentata (bitterbrush) 
recruitment (Monson 2002, p. 2). Natural recruitment of native species 
on the U.S. Air Force's Juniper Butte Range in the Owyhee Plateau 
region is impeded by establishment of T. intermedium (CH2MHill 2008a, 
p. 17). The introduction of these nonnative plants and consequent 
displacement of the native species that comprise late seral stage 
sagebrush habitat contributes to the ongoing degradation and loss of 
quality habitat for Lepidium papilliferum.
    In addition to contributing to the degraded condition of Lepidium 
papilliferum habitat in general, the best

[[Page 52034]]

available data suggest that there may be a negative relationship 
between seeded nonnative plant species and the abundance of L. 
papilliferum. Statistical analyses of habitat type and L. papilliferum 
abundance from surveys conducted from 2000 through 2002 in the Owyhee 
Plateau region indicated that the number of L. papilliferum plants per 
site was three times higher in native sagebrush-steppe habitat areas or 
burned areas that had not been seeded compared to areas seeded with 
Agropyron cristatum (Popovich 2009, p. 25). Similarly, the density of 
L. papilliferum plants was nearly twice as high in a site dominated by 
native grasses than in a site that had been seeded with A. cristatum on 
the Owyhee Plateau (Young 2007, p. 28). Rangewide, there was no 
statistical relationship between A. cristatum cover and L. papilliferum 
abundance based on 2004 through 2008 HIP data (Sullivan and Nations 
2009, p. 136). Although the data regarding A. cristatum in the 
surrounding plant community thus appear to be somewhat equivocal, the 
evidence suggests that A. cristatum successfully competes with and 
ultimately displaces L. papilliferum once it invades occupied 
slickspots (Sullivan and Nations 2009, p. 109).
    Bassia prostrata is another nonnative species that has been used 
for rangeland habitat restoration. Abundant numbers of B. prostrata 
plants have been observed (greater than 1,000 plants) in relatively 
small slickspots, and B. prostrata is documented as a direct competitor 
with Lepidium papilliferum in slickspots (DeBolt 2002; Quinney 2005). 
An evaluation study of the Poen Fire rehabilitation project located in 
the Snake River Plain region documented the loss of L. papilliferum 
along five monitoring transects, coupled with a dramatic increase in B. 
prostrata over a 6-year period following aerial seeding after the fire 
(DeBolt 2002). Observations of four slickspots supporting both L. 
papilliferum plants and B. prostrata plants in 2000 were void of L. 
papilliferum and dominated by B. prostrata in 2005 (Quinney 2005). 
Sullivan and Nations (2009, pp. 110-112) also found that L. 
papilliferum was absent from slickspots when B. prostrata was present; 
this relationship was particularly strong on the Snake River Plain, 
which comprises more than 80 percent of the EO area for L. 
papilliferum. These observations all indicate that B. prostrata is a 
strong competitor with L. papilliferum in slickspots and is capable of 
excluding L. papilliferum from slickspots within a short period of 
time.
    Although Bassia prostrata has not been observed at the HIP 
transects on the OTA (ICDC 2007b, p. 1), it has been documented on five 
HIP monitoring transects in the Snake River Plain region at least once 
between 2004 and 2008. While the majority of these transects have less 
than 1 percent cover of B. prostrata, one transect (19B) is documented 
as having up to 38.5 percent cover of B. prostrata within slickspots 
(Colket 2009, Table 4, p. 39). In 2006, five new observations of B. 
prostrata occurring within slickspots were documented at four HIP 
transects in the Snake River Plain region and one HIP transect in the 
Boise Foothills region, in addition to the three HIP transects located 
on the Snake River Plain region, where it was previously observed. Four 
of these five B. prostrata observations were in permanently marked 
slickspots on HIP transects. As B. prostrata had not been detected in 
the general occurrence area or along the vegetation transect before it 
appeared in the slickspots, this indicates that B. prostrata can invade 
formerly unoccupied slickspots quickly.
    Expansion of seeded B. prostrata into unseeded areas could be 
detrimental to Lepidium papilliferum and its habitat, due to its rapid 
growth within slickspots and ability to replace L. papilliferum within 
slickspots (ICDC 2007a, p. 29; see also discussion above). In addition, 
between 2004 and 2008, B. prostrata was documented in the general area 
around six HIP transects (but not within the slickspots themselves, as 
above); five of these six observations were first detected in 2008 
(Colket 2009, Table 4, pp. 38-46), indicating that this invasive 
species is quickly moving into areas where it has not been observed 
before and that currently support L. papilliferum. Bassia prostrata is 
also documented to occur in slickspots in areas that had not been 
seeded with this invasive forb species after the Poen Fire (DeBolt 
2002), indicating the species is spreading on its own.
    The 2008 HIP monitoring results revealed that, of the 80 HIP 
transects monitored within 54 EOs, 18 transects had some level of 
nonnative, seeded plant cover (Colket 2009, Table 4, pp. 37-49). For 
example, seeded nonnative invasive plant cover was highest on the 
Owyhee Plateau region, where 4 of 22 transects had nonnative, seeded 
species cover between 5 and 10 percent and 11 of 22 transects had 
nonnative, seeded plant cover below 1 percent (Colket 2009, Table 4, 
pp. 46-49). Nonnative, seeded plant cover is minimal in the remainder 
of the range of Lepidium papilliferum, with the Boise Foothills region 
only having 3 of 10 HIP transects with nonnative, seeded plant cover in 
2008, and the Snake River Plain region having only 4 of 48 transects 
with nonnative, seeded plant cover in 2008. In general, the documented 
percentage of nonnative plant cover in the 2008 HIP transect monitoring 
is attributable to Agropyron cristatum, except for one site in the 
Snake River Plain region that contains 14.1 percent cover in Bassia 
prostrata, down from 38.5 percent cover in 2007 (Colket 2009, p. 39). 
Approximately 80 percent (9,163 ac (3,708 ha)) of the Juniper Butte 
Range is dominated by nonnative perennial plant communities as a result 
of past wildfire rehabilitation efforts (U.S. Air Force 1998, pp. 3-120 
to 3-121).
    Increases in cover of invasive, nonnative, seeded grass species may 
also be problematic for Lepidium papilliferum. After HIP transect 715 
was fenced in 2005, Agropyron cristatum cover increased so much that 
the slickspots were barely visible in 2008 (Colket 2009, p. 23). The 
number of L. papilliferum individuals at HIP transect 715 ranged from 
224 to 273 in 2004 and was 286 in 2005, but these numbers dropped to 
16, 17, and 10 plants in 2006, 2007, and 2008, respectively. It is 
unclear whether this decrease in the number of L. papilliferum plants 
is related to the increase in A. cristatum cover and associated litter 
cover in the slickspots (Colket 2009, p. 23).
    Although nonnative seed was formerly used extensively for 
revegetation projects, currently the trend is toward increased use of 
native seed. Management practices involving the use of nonnative seed 
vary among the land management agencies. As specified in a Conservation 
Agreement between the BLM and the Service (U.S. BLM and FWS 2006, p. 
17), Bassia prostrata is not recommended for rehabilitation projects 
within the range of Lepidium papilliferum, although it may be used as a 
last resort species for stabilization projects adjacent to L. 
papilliferum habitat. BLM emphasizes the use of native plants, 
including forbs, in seed mixes and avoids the use of invasive nonnative 
species when possible (State of Idaho et al. 2006, p. 26). In January 
2004, the BLM issued an Instruction Memorandum directing employees to 
comply with CCA requirements for emergency stabilization and wildfire 
rehabilitation activities (State of Idaho et al. 2006, p. 71). Use of 
native species in extensive wildfire rehabilitation projects varies 
based on native seed availability and site conditions that may affect 
seeding success rates. For example, the 2007 Murphy Complex Fire burned 
a portion of areas occupied by L. papilliferum in

[[Page 52035]]

the Owyhee Plateau region. Seed mixtures for emergency stabilization 
and restoration efforts used both native and non-invasive nonnative 
species; however, BLM did not use any Agropyron cristatum, B. 
prostrata, or Thinopyrum intermedium seed in the Murphy Complex Fire 
restoration effort (U.S. BLM 2008a, p. 1). In contrast, 120 ac (48.6 
ha) that burned in the 2005 North Ham Fire, located within Management 
Area 10 in the Snake River Plain region, was drill-seeded with a 
nonnative, perennial grass-seed mixture comprised of 50 percent A. 
cristatum and 50 percent Psathyrostachys juncea (Russian wildrye) (U.S. 
BLM 2008a, p. 16). Drill and aerial seedings implemented in 2006 and 
2007 in response to the Cold Fire (also in Management Area 10) included 
both native and nonnative seed mixtures. In some cases, BLM determined 
post-wildfire seedings using nonnative species were preferable due to 
their ability to compete successfully with the high density of Bromus 
tectorum present in some L. papilliferum MAs (U.S. BLM 2008a, p. 24).
    Although the use of native plant species for post-wildfire 
rehabilitation projects is preferable, there have been ongoing problems 
with the availability and high cost of native seed (Jirik 1999, p. 110; 
Brooks and Pyke 2001, p. 9; Zouhar et al. 2008, p. 265). In recent 
years, BLM has been investing more resources in securing native seed 
and stock reserves through the Great Basin Native Plant Selection and 
Increase Project and the Great Basin Restoration Initiative. 
Consequently, more native seed and plant sources are available for 
ongoing and future restoration efforts for sagebrush-steppe habitat, 
but more progress is needed to ensure the availability and 
affordability of native seed for restoration efforts.
    The U.S. Air Force and the IDARNG have ongoing efforts to address 
invasive, nonnative, seeded plants on their managed lands. The U.S. Air 
Force uses both native and nonnative, non-invasive plant materials and 
does not use Bassia prostrata, Thinopyrum intermedium, or salt-tolerant 
species such as Atriplex canescens (four-wing saltbush) in their 
restoration and revegetation efforts, with native plants used to the 
maximum extent practicable and in concert with the military mission for 
rehabilitation efforts on its lands on the Owyhee Plateau (U.S. Air 
Force 2004, p. R-4). The IDARNG INRMP for the OTA on the Snake River 
Plain includes objectives for maintaining and improving Lepidium 
papilliferum habitat and restoring areas damaged by wildfire. The plan 
specifies that the IDARNG will use native species and broadcast 
seeding, collecting, and planting small amounts of native seed not 
commercially available and will monitor the success of seeding efforts 
(IDARNG 2004, p. 72-73). Since 1991, the IDARNG, using historical 
records, has restored several areas using native seed and vegetation 
that was present prior to past wildfires. The IDARNG continues to use 
restoration methods that avoid or minimize impacts to L. papilliferum 
or its habitat, with an emphasis on maintaining species present in 
presettlement times (IDARNG 2004, p. 73).

Summary of Invasive Nonnative Plant Species

    Invasive nonnative plant species pose a serious and significant 
threat to Lepidium papilliferum, especially when the synergistic 
effects of nonnative, annual grasses and wildfire are considered. 
Invasive, nonnative, unseeded species that pose threats to L. 
papilliferum include the annual grasses Bromus tectorum and 
Taeniatherum caput-medusae that are rapidly forming monocultures across 
the southwestern Idaho landscape. Nonnative plant species contribute to 
increased fire frequency, alter ecological function, outcompete and 
displace native plant species, and degrade the quality and composition 
of sagebrush-steppe habitat for L. papilliferum. The presence of B. 
tectorum in the surrounding plant community shows a consistently 
significant negative relationship with the abundance of L. papilliferum 
across all physiographic regions (Sullivan and Nations 2009, pp. 131, 
137), and a significant negative relationship with L. papilliferum 
abundance within slickspots in the Snake River Plain and Boise 
Foothills regions (Sullivan and Nations 2009, p. 112). These results 
contrast with the information that was available to us at the time of 
our 2007 finding, which did not indicate any statistically significant 
relationship between invasive nonnative plants and the abundance of L. 
papilliferum, either in slickspots or in the surrounding plant 
community (72 FR 1622, p. 1635; January 12, 2007). Additionally, we 
have increasing evidence that nonnative plants are invading the 
slickspot microsite habitats of L. papilliferum (Colket 2009, Table 4, 
pp. 37-49) and successfully outcompeting and displacing the species 
(Grime 1977, p. 1185; DeBolt 2002, in litt; Quinney 2005, in litt; 
Sullivan and Nations 2009, p. 109). Monitoring of HIP transects shows 
that L. papilliferum-occupied sites that were formerly dominated by 
native vegetation are showing relatively rapid increases in the cover 
of nonnative plant species (Colket 2008, p. 1, 33). Regarding B. 
tectorum in particular, vast areas of the Great Basin are already 
dominated by this nonnative annual grass, and projections are that far 
greater areas are susceptible to future invasion by this species 
(Pellant 1996, p. 1). In addition, most climate change models project 
conditions conducive to the further spread of nonnative grasses such as 
B. tectorum in the Great Basin desert area occupied by L. papilliferum 
in the decades to come (see Climate Change under Factor E, below).
    Given the observed negative association between the abundance of 
Lepidium papilliferum and invasive nonnative plants both within 
slickspot microsites and in the surrounding plant community, the 
demonstrated ability of some nonnative plants to displace L. 
papilliferum from slickspots, and the recognized contribution of 
nonnative plants such as Bromus tectorum to the increased fire 
frequency that additionally poses a primary threat to the species, we 
consider invasive nonnative plants to pose a significant threat to L. 
papilliferum. Nonnative grasses such as B. tectorum may additionally 
play a role in increased seed predation that poses a threat to L. 
papilliferum by providing habitat for the expansion of native harvester 
ant colonies (see Factor C, Disease or Predation, below). Currently, 
there are no feasible means of controlling the spread of B. tectorum or 
the subsequent increases in wildfire frequency and extent once B. 
tectorum is established on a large scale (Pellant 1996, pp. 13-14; 
Menakis et al. 2003, p. 287; Pyke 2007). The eradication of other 
invasive nonnative plants poses similar management challenges, and 
future land management decisions will determine the degree to which 
seeded nonnative plants may affect L. papilliferum. Based on the lack 
of effective control mechanisms, the demonstrated increases in 
nonnative plant cover in the range of the species, and the likely 
increases in cover of B. tectorum and other nonnative plant species 
predicted based on their successful invasive characteristics and models 
of climate change, we expect the degree of the threat from invasive 
nonnative plant species to continue and likely increase within the 
foreseeable future. We consider invasive nonnative plants, in 
conjunction with the modified wildfire regime, to pose the greatest 
threat to the viability of L. papilliferum. The significant threat 
posed by invasive nonnative plants is pervasive throughout the range of 
L. papilliferum.

[[Page 52036]]

Development

    Development, as defined for HIP monitoring purposes, includes 
buildings, roads, water tanks, utility lines, railroad tracks, and 
fences (Colket 2009, Appendix A, HIP Protocol, p. 12). Agricultural 
development is recorded under a separate category. Residential, 
commercial, and agricultural development prior to 1955 has been 
reported as the cause for five documented and four probable 
extirpations of Lepidium papilliferum (Colket et al. 2006, p. 4). All 
forms of development can affect L. papilliferum and slickspot habitat, 
whether directly or indirectly, through habitat conversion (resulting 
in direct loss of individuals and permanent loss of habitat), or 
through habitat degradation and fragmentation as a result of consequent 
increased nonnative plant invasions, increased ORV use, increased 
wildfire, and changes to insect populations (ILPG 1999, pp. 1-3; 
Robertson and White 2007, pp. 7, 13).
    The most direct impact of development is the outright loss of 
Lepidium papilliferum populations due to habitat conversion, such as 
when habitat occupied by L. papilliferum is converted to a residential 
development or an agricultural field, resulting in the permanent loss 
of the plant population and the habitat. As mentioned above, 
development has been documented as the cause of several population 
extirpations of L. papilliferum in the past, and at present, there are 
10 approved or proposed development projects located in the Boise 
Foothills and Snake River Plain regions, all within the LEPA 
Consideration Zone (an area that contains Lepidium papilliferum 
identified within the CCA) (State of Idaho 2008). These activities 
include four approved, planned residential communities in Ada County 
totaling 4,062 ac (1,644 ha), and six other development projects 
submitted for approval to Ada County totaling 9,831 ac (3,978 ha). This 
area is in the Boise Foothills, which, although it represents a 
relatively small geographic extent of L. papilliferum's range, supports 
the most dense and regionally abundant populations of the species 
(Sullivan and Nations 2009, p. 103). Several other planned communities 
on an additional 44,500 ac (18,008 ha) are proposed, but have not yet 
been submitted for County or other planning agency approval. In 
addition, large-scale planned communities have been proposed for the 
southern portion of the Snake River Plain region in Elmore County. 
These numbers reflect only planned communities which, by definition, 
are 640 ac (259 ha) or larger and do not include smaller developments, 
such as subdivisions (State of Idaho 2008). Developments of this nature 
likely lead to the extirpation of populations through permanent habitat 
conversion; they may also indirectly impact L. papilliferum, as 
described below. While it is unlikely that all of these planned 
communities will move forward in the near future due to the current 
economic climate, the scale of potential future residential and 
commercial development may impact several of the remaining L. 
papilliferum populations across the range of the species (State of 
Idaho 2008).
    Indirect effects to Lepidium papilliferum are a likely consequence 
of the linear infrastructure associated with urban and residential 
development. In 2006, utility lines and accompanying roads were 
documented running through at least four EOs, natural gas pipelines 
were documented running through two EOs, and existing roads bisect at 
least six EOs (Colket et al. 2006, Appendix C). Additional 
infrastructure associated with the planned development projects 
described above is expected.
    In addition to direct habitat destruction and associated loss of 
individual L. papilliferum plants, utility corridors and roads may 
allow increased ORV access, resulting in potential destruction or 
degradation of slickspots and possible direct mortality of individuals 
of L. papilliferum. They may also increase the chance of nonnative 
plant invasions (most notably Bromus tectorum, as described above), 
human-ignited wildfires, and contribute to habitat fragmentation and 
its associated consequences. The effects of these threats are 
summarized here, and additional details are provided under Invasive 
Nonnative Plant Species and Current Wildfire Regime, above, and Factor 
E, Habitat Fragmentation, below.
    Transportation and utility corridors associated with urban and 
residential development can increase the spread of nonnative invasive 
plants. Roads appear to create avenues for invasion by Bromus tectorum, 
for example, because there is generally a positive significant 
association between nonnative, disturbance-tolerant species such as B. 
tectorum and proximity to roads (Forman and Alexander 1998, p. 210; 
Gelbard and Belnap 2003, pp. 424-425, 430-431; Bradley and Mustard 
2006, p. 1142). Bradley and Mustard (2006, p. 1146) found an even 
stronger association between the presence of B. tectorum and power-line 
corridors, and they suggest that the stronger relationship between B. 
tectorum and recent disturbance (that is, power lines; roads were 
considered an historical disturbance) suggests that future placement of 
either roads or power lines would very likely result in invasion by B. 
tectorum.
    Increased urban and residential development also increases the 
probability of human-ignited wildfires, presumably by increasing the 
area of the urban-wildland interface (e.g., Keeley et al. 1999, p. 
1829; Romero-Calcerrada et al. 2008, pp. 341, 351; Syphard et al. 2008, 
pp. 610-611). Increases in human habitation and activity in the 
rangelands of southern Idaho have contributed to the increase in 
wildfire starts in recent years. For example, in the Jarbidge Field 
Office area of the BLM (Owyhee Plateau region), where 21 of 80 total 
EOs are found, 43 percent of the wildfires occurring since 1987 were 
human-caused (Launchbaugh et al. 2008, p. 3). Proximity to urban areas 
and roads can be an important causal factor associated with wildfire 
ignitions (Kalabokidis et al. 2002, p. 6; Brooks et al. 2004b, p. 3; 
Romero-Calcerrada et al. 2008, p. 351; Syphard et al. 2008, pp. 610-
611).
    Many of the ongoing and planned developments will require the 
construction of power, gas, and other transmission lines, as well as 
new road construction, which will impact and fragment Lepidium 
papilliferum habitats. In addition, several interstate-utility 
activities within the range of L. papilliferum have been proposed, 
including a new electric transmission line between Boardman, Oregon, 
and Murphy, Idaho (Boardman Hemingway project); a new transmission line 
between Casper, Wyoming, and Murphy, Idaho (Gateway West project); and 
a natural gas pipeline proposed, but currently on hold, that would run 
from Opal, Wyoming, through southern Idaho and end in Stanfield, Oregon 
(Sunstone Pipeline project) (State of Idaho 2008). The proposed route 
of the Gateway West Transmission Line project currently bisects habitat 
occupied by L. papilliferum.
    Insect populations may also be affected by development, potentially 
impacting the primary vector of pollination and genetic exchange for 
Lepidium papilliferum. Insect densities have been documented as being 
lower in developed areas than in native habitats (Gibbs and Stanton 
2001, p. 82; McIntyre and Hostetler 2001, p. 215; Zanette et al. 2005, 
p. 117; Clark et al. 2007, p. 333). Changes in native habitat caused by 
ongoing development or conversion of lands to agriculture may impact 
insect pollinator populations by removing specific food sources or 
habitats required for breeding or nesting

[[Page 52037]]

(Kearns and Inouye 1997, p. 298; McIntyre and Hostetler 2001, p. 215; 
Zanette et al. 2005, pp. 117-118). Habitat isolation and fragmentation 
resulting from development may also impact L. papilliferum by 
decreasing pollination from distant sources, possibly resulting in 
decreased reproductive potential (e.g., lower seed set) and reduced 
genetic diversity (see Habitat Fragmentation and Isolation of Small 
Populations, under Factor E, below). Reductions in pollinators due to 
development could thus potentially impact L. papilliferum reproductive 
success as well as contribute to reduced genetic variability, as the 
plant is dependent on insect pollination for successful reproduction 
and the transfer of genetic material between populations.
    Ongoing and planned residential and urban development currently 
threaten the long-term viability of Lepidium papilliferum occurrences 
on private land, primarily in the Snake River Plain and Boise Foothills 
regions (Moseley 1994, p. 20; State of Idaho 2008; Stoner 2009, pp. 13-
14, 19-20). All or portions of 12 L. papilliferum EOs covering 224 ac 
(90.7 ha) (1.0 percent of the total area of all EOs - not including EOs 
managed by cities or counties) occur on private land subject to 
development. Two of these 12 EOs are smaller than 1 ac (0.4 ha) and are 
classified as having fair to poor habitat quality (INHP data as of 
January 14, 2009); therefore, these EOs are particularly vulnerable to 
extirpation through development. Surveys conducted in 2008 documented 
that 21 of 80 HIP transects rangewide are located within 213 ft (65 m) 
of development, and 66 of 80 HIP transects were within 1,640 ft (500 m) 
of development. Proximity to development carries increased risk of 
mechanical disturbances (such as from ORV use), increased risk of 
wildfire ignition and invasion by nonnative plant species, as discussed 
above, and possibly decreases in the diversity or abundance of 
pollinators as well as vulnerabilities associated with fragmentation 
and isolation of small populations, as discussed under Factor E, below.
Summary of Development
    Although the threat of development is relatively limited in scope, 
the impact of development on Lepidium papilliferum can be severe, 
potentially resulting in the direct loss of individuals, and perhaps 
more importantly, the permanent loss of its slickspot microsite 
habitats. The destruction of slickspots is of concern due to the finite 
nature of this limited resource. As described in the Background 
section, L. papilliferum occurs primarily in these specialized 
slickspot microsites. Slickspots and their unique edaphic and 
hydrological characteristics are products of the Pleistocene, and they 
likely cannot be recreated on the landscape once lost. The potential 
loss of slickspots, particularly those slickspots that are occupied by 
the species and thus clearly have the ability to provide the requisite 
conditions to support L. papilliferum, is therefore of great concern in 
terms of providing for the long-term viability of the species. In 
addition, since not all slickspots have above-ground plants in all 
years (see Background section, above), even the loss of currently 
unoccupied slickspots may represent the permanent loss of a finite 
specialized microhabitat that has the potential to support the species. 
Development additionally has the potential for more indirect impacts to 
the species, by contributing to increased habitat fragmentation, 
nonnative plant invasion, human-caused ignition of wildfires, and 
potential reductions in the population of insect pollinators.
    Based on the best available information, past development has 
eliminated some historical Lepidium papilliferum EOs, and planned and 
proposed future developments threaten several occupied sites in the 
Snake River Plain and Boise Foothills regions. Most of the recent 
development has primarily occurred on the Snake River Plain and Boise 
Foothills regions, which collectively comprise approximately 83 percent 
of the extent of EOs; development has not been identified as an issue 
on the Owyhee Plateau (Stoner 2009, pp. 13-14, 19-20). We are aware of 
10 approved or proposed development projects planned for these regions 
(State of Idaho 2008, pp. 3-5), which would affect 13 out of 80 EOs (16 
percent of EOs). Though these developments are not certain to occur, 
they represent the likely location and magnitude of development over 
the foreseeable future. Development of sagebrush-steppe habitat is of 
particular concern in the Boise Foothills region, which, although 
relatively limited in its geographic extent, supports the highest 
abundance of L. papilliferum plants per HIP transect (Sullivan and 
Nations 2009, pp. 3, 103, 134).
    We consider development to be a significant threat within the Boise 
Foothills and Snake River Plain portions of the range of Lepidium 
papilliferum, as the outcome of this threat is severe where it occurs 
and likely results in the permanent loss of populations and 
irreplaceable slickspot microsite habitats. However, this threat is not 
so imminent or sweeping in scope as to pose an immediate risk of 
extirpation to the populations of L. papilliferum in these regions, nor 
do we consider the threat of development to be equal to the magnitude 
and intensity of the primary threats of the modified wildfire regime 
and invasive nonnative plants. We consider development to pose a 
significant but lesser threat to the species.

Livestock Use

    Livestock use in areas that contain Lepidium papilliferum has the 
potential to result in both positive and negative effects on the 
species, depending on factors such as stocking rate and season of use. 
Herbivory by livestock does not appear to be a problem, as L. 
papilliferum seems to be largely unpalatable to anything but insects 
(see Factor C, Disease or Predation, below). Livestock herbivory of 
invasive nonnative plants, especially annual grasses such as Bromus 
tectorum, is suggested as one of the potential benefits of livestock 
use that may contribute to the restoration of the sagebrush-steppe 
ecosystem (e.g., Pellant 1996, pp. 6, 10, 13). At the same time, 
livestock use may have negative effects on L. papilliferum. Trampling 
from livestock may result in direct damage or mortality of individual 
L. papilliferum plants, and the mechanical disturbance damages the 
slickspot soil layers, altering slickspot function and creating 
conditions conducive to the invasion of weedy nonnative plants.
    Trampling damage to individual L. papilliferum plants appears to be 
relatively isolated, and occasional damage or mortality of individual 
above-ground plants is probably not of much consequence to the species 
as a whole, because studies and modeling of L. papilliferum's life 
cycle indicate that the persistence of the plant is largely dependent 
on the proliferation of the seed bank (Palazzo et al. 2005, pp. 2-4, 8-
9; Meyer et al. 2006, p. 900). If trampling results in the mortality of 
individual plants prior to seed set, however, that will have a negative 
impact on the persistence of the seed bank itself by reducing the 
number of seeds added.
    Livestock trampling can also disrupt the soil layers of slickspots, 
altering slickspot function (Seronko 2004; Colket 2005, p. 34; Meyer et 
al. 2005, pp. 21-22). Trampling when slickspots are dry can lead to 
mechanical damage to the slickspot soil crust, potentially resulting in 
the invasion of nonnative plants and altering the hydrologic function 
of slickspots. In water-saturated slickspot soils, trampling by 
livestock can break through the restrictive clay layer; this is 
referred to as penetrating trampling

[[Page 52038]]

(State of Idaho et al. 2006, p. 9). Trampling that alters the soil 
structure and the functionality of slickspots (Rengasamy et al. 1984, 
p. 63; Seronko 2004) likely impacts the suitability of these microsites 
for L. papilliferum. Trampling can also negatively affect the seed bank 
by pushing seeds too deeply into the soil for subsequent successful 
germination and emergence. Meyer and Allen (2005, pp. 6-8) found that 
seed emergence success decreased with increasing depth in the soil, 
from a mean of 54 percent at the shallowest planting depth of 0.1 in (2 
mm) to a mean emergence success of 5 percent at 1.2 in (30 mm) planting 
depth.
    Two documented incidents suggest that trampling has the potential 
to negatively affect L. papilliferum, as penetrating livestock-
trampling events at sites occupied by L. papilliferum were followed by 
large reductions in plant abundance in subsequent years, in one case 
going from thousands of plants annually to fewer than 10 plants 
recurring each year (Robertson 2003b, p. 8; Meyer et al. 2005, p. 22). 
Trampling has been suggested as the likely cause of the ensuing 
population reductions in these two incidents, but as these were 
observational reports, it is not known whether other factors may have 
also acted on these populations. A third incident occurred in 2005 at a 
HIP transect monitoring in EO 68, in the New Plymouth Management Area 
of the Boise Foothills region. In this incident, penetrating livestock 
trampling was observed in 3 of 10 slickspots on the transect to a depth 
of 3 in (8 cm), but not to the extent that the livestock penetrating-
trampling trigger was tripped (the trampling ``trigger'' refers to a 
threshold for trampling set in the CCA, and is defined as breaking 
through the restrictive layer under the silt surface area of a 
slickspot during saturated conditions; State of Idaho et al. 2006, p. 
9). Since that time, L. papilliferum numbers at this transect were 
substantially reduced, going from between 631 to 1,277 plants observed 
in 2004 to a total of 9 plants in 2005 and 3 plants in 2006. Similar 
reductions in plant abundance were not observed in other HIP transects 
in the New Plymouth MA, indicating that environmental factors shared by 
these sites were likely not responsible for the observed declines 
(Colket 2006, pp. 10-11). In 2007 and 2008, L. papilliferum numbers in 
this transect appeared to be slowly increasing (167 plants in 2007 and 
224 plants in 2008), but had not reached the levels observed in 2004 
prior to the incident (Colket 2009, p. 31).
    Penetrating trampling by livestock may have a potentially 
detrimental effect on Lepidium papilliferum; however, these effects 
appear to be seasonal (most detrimental when soils are wet in the 
spring) and localized in nature. While we acknowledge that livestock 
use may have negative impacts on individual slickspots, statistical 
analyses of monitoring data available at this time have not 
demonstrated a significant correlation between livestock use and the 
abundance of L. papilliferum on a rangewide basis. In a statistical 
analysis of HII data from 1998 to 2001, recent livestock use did not 
appear to have any effect on Lepidium papilliferum, slickspot 
attributes, and plant community attributes (Menke and Kaye 2006a, p. 
iii). The evidence from this study is not strong, however, as the 
analysis of grazing impacts were limited to areas that had already been 
burned and had likely been previously grazed (Menke and Kaye 2006a, pp. 
18-19). These researchers recommended additional analysis to confirm 
their findings (Menke and Kaye 2006a, p. iii). Later statistical 
analyses using additional years of rangewide HIP data, based on 4 years 
(2005 to 2008) and 5 years (2004 to 2008) of livestock use, also showed 
no significant relationships between L. papilliferum abundance and 
penetrating livestock trampling in slickspots (Salo 2009, p. 1; 
Sullivan and Nations 2009, p. 122), or between L. papilliferum 
abundance and total livestock-print cover or livestock-feces cover in 
slickspots (Sullivan and Nations 2009, p. 122). Statistical analyses of 
L. papilliferum data from 3 years of surveys on the Owyhee Plateau 
(2000-2002) showed that sites with low levels of livestock trampling 
exhibited greater numbers of L. papilliferum plants (averaging twice 
the total number of plants) than sites with high levels of trampling, 
although these results were statistically significant for only the year 
2000. A significant positive relationship was also found between L. 
papilliferum abundance and distance to water and salt stations for use 
by livestock, with total plant abundance increasing with increasing 
distance away from water or salt sources (Popovich 2009, pp. 27-28).
    A 2-year study designed to examine the relationship between 
livestock trampling effects and Lepidium papilliferum density did not 
show a significant change in L. papilliferum density as a result of the 
trampling treatment applied. Year-to-year variations in L. papilliferum 
density observed in this 2-year study were attributed to stochastic 
environmental factors and not trampling events (Young 2007, p. 19). 
Further research is needed to determine if higher levels of trampling, 
greater mean hoof print depths, or more frequent trampling treatments 
may affect L. papilliferum abundance (Young 2007, pp. 19-20). The 
ability to discern any livestock trampling effects was limited since 
all study areas were grazed 2 to 4 years prior to initiation of the 
study.
    Livestock trampling events most likely to adversely affect Lepidium 
papilliferum usually occur when large numbers of livestock are 
concentrated on or around slickspots that are saturated with water 
(Hoffman 2005; Meyer et al. 2005, pp. 21-22). Saturated conditions 
typically exist for short periods each year and may never occur in some 
(drought) years (Hoffman 2005). Under the CCA, penetrating trampling is 
monitored to avoid livestock-related impacts to slickspots containing 
L. papilliferum. Penetrating trampling is defined by the CCA as 
breaking through the restrictive layer (i.e., the middle layer of 
slickspot soil that supports L. papilliferum, as described by Meyer and 
Allen 2005, p. 3) under the silt surface area of a slickspot during 
saturated conditions (State of Idaho et al. 2006, p. 9). Predicting 
when soils will be wet in a climate with few and inconsistent 
precipitation events is difficult. Supplemental salt and watering sites 
can alter livestock distribution, and depending on location, can 
increase or decrease trampling of slickspots. As described below, 
protective measures provided in several of the existing conservation 
plans for L. papilliferum are designed specifically to prevent or 
minimize the impacts to the species from livestock trampling, 
particularly during the seasons when slickspot soils are wet and most 
susceptible to damage.
    There are also indirect effects from livestock use that have 
impacted the sagebrush-steppe ecosystem. Livestock use has been 
suggested as a contributing factor to the spread of both native and 
invasive nonnative plant species (e.g., Young et al. 1972, pp. 194-201; 
Hobbs and Huenneke 1992, p. 329; Frost and Launchbaugh 2003, pp. 43-45; 
Loeser et al. 2007, p. 95). The spread of Bromus tectorum across 
portions of the Snake River Plain has been attributed to several 
causes, including the past practice of intensive livestock use in the 
late 1800s (Mack 1981, pp. 145-165).
    A small number of case studies from western North America suggest 
that grazing plays an important role in the decrease of native 
perennial grasses and an increase in dominance by nonnative annual 
species; however, invasion by nonnative grasses has been found to occur 
both with and without grazing in

[[Page 52039]]

some areas. Today, nonnative annual plants such as Bromus tectorum are 
so widespread that they have been documented spreading into areas not 
impacted by disturbance (Piemeisel 1951, p. 71; Tisdale et al. 1965, 
pp. 349-351; Stohlgren et al. 1999, p. 45); therefore, the absence of 
livestock use no longer protects the landscape from invasive nonnative 
weeds (Frost and Launchbaugh 2003, p. 44), at least with respect to B. 
tectorum.
    Analysis of 3 years of HII data, from 1999 through 2001, showed no 
effect of livestock grazing on slickspot perimeter integrity, weedy 
species density, perennial forb or grass establishment, or organic 
debris accumulation in slickspots (Menke and Kaye 2006a, p. 10). 
Cumulative livestock sign (indicators of livestock presence) had a 
significant negative correlation with exotic grass dominance around 
slickspots (Menke and Kaye 2006a, p. 11), and with the frequency of 
slickspots with dense weedy annuals in 2001 (Menke and Kaye 2006a, p. 
10). The analysis of grazing effects was limited since the HII data 
were observational only (no controlled experiments were performed), all 
areas were likely grazed at some point in the past, and grazing effects 
could only be observed in habitats that had burned in the past (Menke 
and Kaye 2006a, p. 18). In addition, there was no significant 
difference in cover of exotic plant species in slickspots between 
grazed and ungrazed areas in the 2004 HIP dataset, although soil crust 
cover was significantly lower in grazed transects (Menke and Kaye 
2006b, p. 19). As described above, biological soil crusts are important 
to the sagebrush-steppe ecosystem and slickspots where Lepidium 
papilliferum occur as they stabilize and protect soil surfaces from 
wind and water erosion, retain soil moisture, discourage annual weed 
growth, and fix atmospheric nitrogen (Eldridge and Greene 1994 as cited 
in Belnap et al. 2001, p. 4). Young (2007, p. 19) did not find a 
significant change in the density of Bromus tectorum, Ceratocephala 
testiculata, and Lepidium perfoliatum following the application of a 
one-time, annual trampling treatment over a 2-year period. Both studies 
(Menke and Kaye 2006a,b; Young 2007) represent short-term data sets 
that likely are not capable of reflecting any potential long-term 
effects to L. papilliferum habitat.
    The potential benefit of livestock use in reducing wildfire effects 
through a reduction of fine fuels has generated discussion in recent 
years (e.g., Pellant 1996; Loeser et al. 2007). The introduction of 
cattle, sheep, and horses to the Great Basin in the 1860s quickly 
created large ranching operations and grazing pressure. Heavy livestock 
grazing removed fine fuels and resulted in a substantial reduction in 
the number of fires and the acres burned. Only 44 fires, burning a 
total of 11,000 ac (6,875 ha), were reported from 1880 to 1912 in Great 
Basin rangelands (Miller and Narayanan 2008, p. 9). The number of 
livestock in Great Basin and sagebrush ecosystems has dropped rapidly 
since the passage of the Taylor Grazing Act of 1934 (43 USC 315; http://www.blm.gov/wy/st/en/field_offices/Casper/range/taylor.1.html, 
accessed July 23, 2008, as cited in Launchbaugh et al. 2008, p. 2). 
Livestock numbers in Idaho decreased in the 1950s primarily from loss 
of large sheep operations. Livestock numbers have fluctuated at, or 
below, this initial decrease through the remainder of the twentieth 
century, with a steady conversion from sheep to cattle. In the last 
decade, a substantial decrease in authorized use of livestock grazing 
on BLM lands in Idaho has been recorded (Launchbaugh et al. 2008, p. 
2).
    With careful management, livestock grazing may potentially be used 
as a tool to control B. tectorum (Frost and Launchbaugh 2003, p. 43) 
or, at a minimum, retard the rate of invasion (Loeser et al. 2007, p. 
95). Although the spread of B. tectorum has been strongly linked with 
high-impact grazing, there is some evidence to indicate that grazing at 
more moderate levels may potentially inhibit the colonization of B. 
tectorum (e.g., Loeser et al. 2007, pp. 94-95); the researchers note, 
however, that experimental study over a longer time period is needed to 
verify this tentative conclusion. Others, however, have suggested that 
given the variability in the timing of B. tectorum germination and 
development, and its ability to spread vegetatively, effective control 
of B. tectorum through livestock grazing may be a challenge (Hempy-
Mayer and Pyke, 2008, p. 121). While it is difficult to discern the 
relative importance of grazing, climate, and wildfire in contributing 
to nonnative plant abundance (D'Antonio et al. 1999, as described in 
Zouhar et al. 2008, pp. 23-24), areas with a history of livestock 
grazing often support a wide variety of nonnative species, especially 
in areas where nonnatives have been introduced to increase the forage 
value of rangelands or pastures (Zouhar et al. 2008, pp. 23-24).
    Following investigations of the 2007 Murphy Wildland Fire Complex, 
fire-modeling efforts revealed that grazing in grassland vegetation can 
reduce the surface rate of spread and fire-line intensity to a greater 
extent than grazing in shrubland vegetation (Launchbaugh et al. 2008, 
pp. 1-2). Under extreme fire conditions (low fuel moisture, high 
temperatures, and gusty winds), however, grazing applied at moderate 
utilization levels has limited or negligible effects on fire behavior. 
When weather and fuel-moisture conditions are less extreme, grazing may 
reduce the rate of spread and intensity of fires, allowing for patchy 
burns with low levels of fuel consumption (Launchbaugh et al. 2008, pp. 
1-2). Some research also indicates that grazed areas have a reduced 
likelihood of wildfire ignitions, likely by reducing the availability 
of fine fuels (Romero-Calcerrada et al. 2008, p. 351). Launchbaugh et 
al. 2008 (p. 32) state that ``changes in grazing management aimed at 
managing fuel loads are not appropriate for homogeneous application 
across large landscapes and multiple management units. Such application 
of grazing across entire landscapes at rates necessary to reduce fuel 
loads and affect fire behavior, especially under extreme conditions, 
could have negative effects on livestock production and habitat 
goals.'' Targeted grazing to accomplish fuel objectives holds promise, 
but requires detailed planning that includes clearly defined goals for 
fuel modification and appropriate monitoring to assess effectiveness 
(Launchbaugh et al. 2008, p. 32).
    Existing conservation plans (CCA, U.S. Air Force INRMP, IDARNG 
INRMP) contain numerous measures to avoid, mitigate, and monitor the 
effects of livestock use on Lepidium papilliferum. Livestock-grazing 
conservation measures implemented through the State of Idaho CCA and 
the U.S. Air Force INRMP apply to all Federal and State-managed lands 
within the occupied range of Lepidium papilliferum (98 percent of the 
acreage). Conservation measures prescribed by the CCA include minimum 
distances for placement of salt and water troughs away from occurrences 
of L. papilliferum. Several troughs and salt blocks have been moved as 
a result of these measures (State of Idaho et al. 2005; State of Idaho 
et al. 2006, p. 133). The CCA also includes measures to reduce 
livestock trampling during wet periods, including trailing (moving 
cattle to, or between, allotments repeatedly on the same path) 
restrictions (State of Idaho et al. 2006, pp. 132-134). High-priority 
L. papilliferum EOs identified in the CCA tend to have more restrictive 
conservation measures, such as no early spring grazing, fencing to 
exclude

[[Page 52040]]

livestock, and delaying turnout of livestock onto allotments when soils 
are saturated (State of Idaho et al. 2006, pp. 133-134). Delay of 
turnout is important following a soil-saturating precipitation event in 
areas containing L. papilliferum since it is difficult to avoid 
trampling effects on saturated slickspot soils. As part of the CCA, 
high-priority EOs were designated to emphasize protection and 
restoration of L. papilliferum habitats. Criteria for designating these 
EOs were based on existing habitat quality, geographic location 
relative to other existing EOs, minimal land-use activities, the 
absence or presence of resources to address threats, and the need to 
preserve enough EOs throughout the species' range to prevent extinction 
in case of a catastrophic event. To protect these high-priority EOs, 
BLM has shifted the season of livestock use on some allotments from 
spring to fall, and implemented a deferred-rotation management system 
on some allotments to protect annual flowering L. papilliferum plants 
from grazing impacts (State of Idaho et al. 2006, pp. 133-134).
    Under the Juniper Butte Range INRMP, the U.S. Air Force utilizes 
livestock grazing as the primary means to minimize wildfire risk by 
reducing the amount of standing grass biomass (U.S. Air Force 2004, pp. 
6-37 to 6-39). Livestock use occurs annually for up to 60 days while 
the Juniper Butte Range is shut down for clean-up and target 
maintenance. The military training shutdown period lasts a maximum of 
60 days within a 90-day period, from April 1 through June 30 (U.S. Air 
Force 2000, pp. B-18 to B-21). The INRMP avoids livestock turnout onto 
the range when slickspots are wet in order to reduce trampling impacts 
to slickspot habitats, and then uses annual monitoring of slickspot 
soil moisture to determine appropriate livestock turnout dates for the 
Juniper Butte Range (U.S. Air Force 2000, pp. B-18 to B-21). 
Additionally, in 2002 the U.S. Air Force established three fenced 
enclosure areas of 173 ac (70.0 ha), 8 ac (3.2), and 30 ac (12.1 ha), 
respectively, to preclude all disturbance activities and promote 
Lepidium papilliferum research and seed collection (Binder in litt. 
2006) compatible with the Air Force mission.
Summary of Livestock Use
    Evidence of the direct and indirect potential impacts to Lepidium 
papilliferum and slickspots from livestock use is relatively limited 
with the data currently available. We recognize the potential for 
negative impacts to L. papilliferum populations and slickspots that may 
result from seasonal, localized trampling events. However, with the 
implementation of conservation measures to minimize potential direct 
and indirect impacts of livestock to L. papilliferum, such as 
restricting livestock access to areas occupied by L. papilliferum when 
slickspot soils are wet and thus most vulnerable to damage, we consider 
livestock use to be a lesser threat to the species than the primary 
threats posed by the altered wildfire regime and associated increase in 
nonnative, invasive plant species within the range of L. papilliferum. 
We acknowledge that current data may not be adequate to detect time-
dependent issues associated with livestock use as only 5 years of HIP 
data are available (Sullivan and Nations 2009, p. 137), and encourage 
the continued implementation of conservation measures and associated 
monitoring to ensure potential impacts of livestock trampling to L. 
papilliferum are avoided or minimized. Under current management 
conditions, we do not consider livestock use to pose a significant 
threat to L. papilliferum.

Wildfire Management and Post-Wildfire Rehabilitation

    Some activities associated with wildfire management, including fuel 
management projects (e.g., greenstrips, prescribed fire), wildfire 
suppression activities, and post-wildfire rehabilitation, can 
potentially impact existing Lepidium papilliferum occurrences and 
damage slickspot habitat by mechanical disturbances or by facilitating 
the establishment of nonnative plant species (ILPG 1999). At the same 
time, wildfire management and post-wildfire rehabilitation activities 
have the potential to benefit L. papilliferum by reducing the 
occurrence and extent of wildfire and by revegetating its habitat with 
native plant species to prevent the encroachment of invasive nonnative 
grasses and other nonnative plant species, thus reducing two of the 
most significant threats to the viability of the species.
    The direct effects of wildfire management activities may include 
injury or mortality of individual plants, and possibly damage to or 
destruction of the seed bank, through mechanical disturbance or direct 
exposure to herbicides. Indirect effects associated with mechanical 
disturbance of slickspot soils include an increased probability of 
establishment of invasive nonnative plants, burial of the seed bank to 
a depth where seedlings cannot emerge from the soil, and mixing of 
slickspot soil layers, which affects slickspot function and the 
suitability of a microsite for successful support of the species.
    Drill seeding is a rangeland rehabilitation technique that is often 
used to restore vegetation after wildfire using a rangeland drill that 
plants and covers seed simultaneously in furrows. Drill seeding is 
designed to give the seeds moisture and temperature advantages to 
enhance their competitive fitness and, consequently, increase their 
survival rate (Scholten and Bunting 2001, p. 3). Drill seeding has been 
used on wildfire rehabilitation projects on BLM lands where Lepidium 
papilliferum occurs. It impacts slickspots through mechanical 
disturbance and introduces other, often nonnative, plant materials. 
Historically, slickspots were not understood to have any special 
ecological value, so no attempt was made to avoid them during 
rehabilitation activities. Although more recent land management actions 
have established buffers to protect slickspots and L. papilliferum from 
herbicide use, we have no data on how the physical disturbance from 
past drill seedings has affected L. papilliferum habitats. Although 
drill seeding may have less severe impacts on slickspot habitat than 
disking the soil, the success of restoring slickspots and L. 
papilliferum plants using drill seeding varies considerably. The 
benefits of post-fire revegetation to prevent the establishment of 
Bromus tectorum and subsequent recovery of soil surfaces conducive to 
germination and establishment of native perennial grass and shrub 
communities may outweigh the impacts from the initial short-term 
disturbance associated with drill seeding (Young and Allen 1996, pp. 
533-534; Bunting et al. 2003, pp. 82-85). For further information on 
the effects of nonnative species used for rehabilitation and 
restoration efforts in L. papilliferum habitats, see the Seeded 
Nonnative Invasive Plants section above.
    Rangewide, disk or drill seeding has occurred on portions of 3 of 
16 EOs in the Boise Foothills region, 10 of 43 EOs in the Snake River 
Plain region, and 9 of 21 EOs on the Owyhee Plateau region (Cole 2009b, 
Threats Table). The effect of drill seeding is also monitored as part 
of the rangewide HIP transects monitoring. In 2008, of the 80 Lepidium 
papilliferum transects monitored, 1 transect in the Boise Foothills 
region, 1 transect in the Snake River Plain region, and 9 transects in 
the Owyhee Plateau region had evidence of old drill seedings within 
slickspots (Colket 2009, pp. 66-67). In a 3-year study on the Owyhee 
Plateau from 2000 through 2002, Popovich (2009, pp. 8, 11) found that 
unseeded sites supported three

[[Page 52041]]

times as many L. papilliferum on average as sites that had been seeded. 
However, it is unclear whether the reduction in L. papilliferum numbers 
at seeded sites is the result of the physical disturbance of slickspot 
soils associated with drill seeding, competition from the seeded, 
nonnative invasive grass planted at these sites (Agropyron cristatum), 
or a combination of the two.
    In 2006, rangeland emergency stabilization and rehabilitation 
activities were implemented on the Snake River Plain region in response 
to seven fires (8,312 ac (5,190 ha)) that burned in 2005, and one fire 
that burned in 2006 (161 acres (65 ha)). In 2007, rangeland 
rehabilitation work was implemented for 10 additional wildfires that 
burned in 2006. The rehabilitation activities included drill seeding 
utilizing low-impact, no-till drills, herbicide treatment, and aerial 
seeding (U.S. BLM 2008a, pp. 4, 8, 13, 16). On the Owyhee Plateau, non-
ground-disturbing techniques were used following the Murphy Complex 
Fire for seeding in areas documented to support Lepidium papilliferum 
(U.S. BLM 2008b, Murphy map).
    Ground disturbance associated with wildfire control, such as the 
establishment of fire lines (areas with vegetation removed to break 
fuel continuity), fire camps, firefighting staging areas, and the use 
of wildfire-suppression vehicles, can also impact existing Lepidium 
papilliferum occurrences and damage slickspot habitat (ILPG 1999). For 
example, in 2007, dual-wheel pickup tracks that appeared to have been 
associated with wildfire suppression efforts in 2006 were observed in 5 
slickspots (HIP transect 032 in Management Area 5) during the 2007 HIP 
transect monitoring in the Snake River Plain region (ICDC 2008, p. 9).
    Firefighting crews and their equipment may also indirectly impact 
Lepidium papilliferum through dispersal of invasive-plant propagules 
(e.g., seeds or vegetative structures) as they travel from other 
regions to wildfires in southern Idaho, or travel within the local area 
of the fire. As fire camps are typically set up in large, flat 
clearings that have been disturbed in the past, these areas often 
support populations of invasive plants. Propagules of these plants 
adhere to fire personnel and their equipment, and may be dispersed 
elsewhere as crews move about (Zouhar et al. 2008, p. 273), potentially 
contributing to nonnative plant invasions in L. papilliferum habitat.
    The construction of fuel breaks intended to slow the movement of 
wildfire can benefit Lepidium papilliferum by protecting slickspots 
from burning. However, the construction of fuel breaks may also 
negatively impact L. papilliferum through ground disturbance or the use 
of native seeded species. Nonnative species (such as Agropyron 
cristatum and Bassia prostrata) are planted in fuel breaks as 
greenstrips. Greenstrips are expected to slow the spread of wildfire as 
the plants remain green (retain higher fuel moisture so are less 
flammable) for longer periods than annual plants such as Bromus 
tectorum. Wildfire control lines have been documented in three EOs, one 
in the Boise Foothills region and two in the Snake River Plain region, 
although none have documented wildfire control lines within slickspots 
(Colket et al. 2006, Appendix C; ICDC 2008, p. 9; Cole 2009b, Threats 
Table). In 2004, the Boise District of BLM developed a strategy to 
assess the feasibility of creating fuel breaks to protect L. 
papilliferum. A field assessment was conducted of over 84,550 ac 
(22,075 ha) of L. papilliferum habitat to identify potential fuel break 
routes. Nearly 125 mi (78 km) of potential fuel breaks were identified 
that would utilize existing roads and trails, in areas that could 
potentially protect up to 10,436 ac (6, 523 ha) containing L. 
papilliferum habitat within the LEPA Consideration Zone. None of these 
potential fuel breaks have been constructed as of spring 2008. There 
was one fuel break established in 2006 and 2007 along Interstate 84 
from milepost 71 (Mayfield Exit) to milepost 89 (Mountain Home exit) by 
the Idaho Department of Transportation, a distance of approximately 30 
mi (19 km). This fuel break likely reduced the number of wildfires 
escaping this stretch of Interstate 84, which is a source of frequent 
fire ignitions threatening several L. papilliferum occupied sites 
located in the Snake River Plain region (U.S. BLM 2008a, p. 20).
    Through the 2006 CCA, BLM has implemented conservation measures 
designed to avoid or minimize impacts to the species from wildfire 
prevention, wildfire suppression, and post-wildfire, rangeland-
rehabilitation activities (State of Idaho et al. 2006, Table 5). 
Rangeland rehabilitation and restoration standard-operating procedures 
for areas occupied with Lepidium papilliferum were first addressed in 
an Instruction Memorandum in January 2004 (State of Idaho et al. 2005, 
p. 33). Today, the BLM and fire cooperators distribute maps and inform 
crew members of the location of L. papilliferum to maximize wildfire 
protection in those areas, and to minimize potential impacts from fire-
suppression activities (State of Idaho et al. 2006, p. 26). One 
conservation measure of the CCA instructs the BLM to use seeding 
techniques that minimize soil disturbance, such as no-till drills and 
rangeland drills equipped with depth bands. Implementation of these 
measures for rehabilitation and restoration projects have the potential 
to minimize the impact to L. papilliferum and its slickspot habitats 
(State of Idaho et al. 2006, p. 26). The BLM also avoids spraying 
herbicides within or near known occupied L. papilliferum habitat, and 
conducts pretreatment surveys on at least 5 percent of previously 
unsurveyed habitat prior to herbicide or ground disturbing treatments 
associated with emergency wildfire-rehabilitation activities (State of 
Idaho et al. 2006, p. 27). More recently, site-specific conservation 
measures to avoid or minimize potential impacts to L. papilliferum and 
its slickspot habitat were incorporated as part of a temporary, 
livestock-control fencing project in response to the Inside Desert Fire 
(in the Owyhee Plateau region) emergency stabilization and 
rehabilitation efforts (U.S. BLM 2008b, p. 3).
    The U.S. Air Force and IDARNG also have implemented a number of 
ongoing efforts to minimize the impacts of wildfire-management 
activities. For example, the U.S. Air Force, like the BLM, uses drill 
seeders equipped with depth bands to minimize soil disturbance and 
avoids slickspots to the maximum extent practicable in drill seeding 
efforts. The U.S. Air Force uses broadcast seeding to the maximum 
extent practicable consistent with reseeding goals and uses wildfire 
indices to restrict activities when the wildfire rating hazard is 
extreme (U.S. Air Force 2004, pp. R-3, R-4). On the OTA, the IDARNG 
restores wildfire-damaged areas by broadcast seeding native species. As 
part of their annual training, the IDARNG provides their fire crews 
with maps of all known Lepidium papilliferum occupied habitat, and 
actively suppresses all wildfires on the OTA. Blading is not permitted 
in L. papilliferum habitat areas on the OTA, and existing roadways 
serve as fuel breaks and allow for quick access for wildfire management 
(IDARNG 2004, p. 73). Since 1987, the IDARNG has demonstrated that 
efforts to suppress wildfire and the use of native species with minimal 
ground-disturbing activities can be effective in reducing the wildfire 
threat, as well as in reducing rates of spread of nonnative

[[Page 52042]]

invasive species associated with wildfire management activities (IDARNG 
2004, p. 73). In 2008, the IDARNG also initiated maintenance on a 
series of identified fuel breaks on the OTA. These fuel breaks are 
designed to act as barriers to prevent fires that might be ignited by 
military-training activities from spreading into adjacent L. 
papilliferum habitat (U.S. BLM 2008a, p. 20).
Summary of Wildfire Management and Post-Wildfire Rehabilitation
    Wildfire management may have both positive consequences (the 
control of wildfires) and negative consequences (the destruction of 
slickspots or inadvertent introduction of invasive nonnative plants) 
for Lepidium papilliferum and its habitat, depending on how the 
activity is implemented. The negative consequences of wildfire 
management and rehabilitation activities appear to be relatively 
limited in both scope and severity, however, and we do not consider 
these negative effects to outweigh the positive effects of successful 
wildfire control, given that we consider frequent wildfires to be one 
of the primary threats to the species. On balance, wildfire and post-
wildfire rehabilitation activities likely improve the status of the 
species. We therefore do not consider wildfire management or post-
wildfire rehabilitation activities to be a significant threat to L. 
papilliferum.

Military Training

    Military activities within the range of Lepidium papilliferum 
include ordnance-impact areas, training activities, and military 
development. Military-training activities occur at, or near, 4 of 80 
extant EOs: 3 at the OTA on the Snake River Plain, and a portion of 1 
EO at the Juniper Butte Range on the Owyhee Plateau. INRMPs have been 
developed and implemented for both the Juniper Butte Range and the OTA. 
The INRMPs provide management direction and conservation measures to 
address or eliminate the effects from military-training exercises on L. 
papilliferum and its habitat. Both the IDARNG (Quinney 2008; ICDC 2008, 
p. 21) and the U.S. Air Force (CH2MHill 2008a, pp. 1, 17) conduct 
annual monitoring to ensure impacts to the species due to training 
activities are either avoided or minimized. The IDARNG has implemented 
conservation measures for 18 years on the OTA, which currently supports 
nearly 60 percent of the highest-quality habitat rangewide (B-ranked, 
EO 27). This suggests that the conservation measures are effective in 
maintaining generally intact native plant vegetation and limiting 
anthropogenic disturbances on the OTA since it contains much of the 
best remaining habitat for L. papilliferum (Sullivan and Nations 2009, 
p. 91).
Summary of Military Training
    The IDARNG and the U.S. Air Force continue to implement 
conservation efforts to avoid or reduce adverse effects of military 
training on Lepidium papilliferum and its habitat. Since the areas 
managed by the IDARNG and the U.S. Air Force continue to support some 
of the highest-quality habitat remaining for L. papilliferum, we 
consider the measures to minimize the impact of military-training 
exercises on the species and its habitat to have been effective. The 
IDARNG and U.S. Air Force are committed to continuing the 
implementation of these conservation measures into the future, through 
the CCA and their respective INRMPs. The threat of military training is 
localized in area, and minimal in significance across the range of the 
species, therefore we do not consider military training to pose a 
significant threat to L. papilliferum.

Recreation

    Recreational activities that may affect Lepidium papilliferum 
include hiking, cycling, horseback riding, and the use of ORVs. These 
activities would be expected to impact the species primarily through 
mechanical disturbance (e.g., disruption of the slickspot soil layers, 
resulting in the reduction or loss of slickspot integrity and function) 
or crushing of individual plants, potentially resulting in injury or 
mortality. Areas where military training activities occur, such as the 
Juniper Butte Range and some areas of the OTA, are restricted from 
recreational activities because of military use.
    ORV use has been documented in 22 of the 80 Lepidium papilliferum 
EOs (8 of 16 on the Boise Foothills, 14 of 42 on the Snake River Plain, 
and none on the Owyhee Plateau) for which habitat information has been 
collected (Cole 2009b, pp. 1-2). Effects from recreational activities, 
such as mechanical disturbance of soils from ORV use, are monitored as 
part of the rangewide HIP monitoring for L. papilliferum. ORV tracks 
were not detected in any EO or Management Area during 2008 HIP 
monitoring (Colket 2009, p. 9). In 2007, ORV tracks were detected at 2 
of the 80 HIP transects sampled (ICDC 2008, p. 9). Dual-wheel truck 
tracks were also detected at 2 other transects. An earlier analysis of 
HII transects monitored between 1998-2001, and HIP transects during 
2004-2006 indicated that ORV use was detected at only a few transects 
each year and that impacts appeared to be minimal.
    Cycling and pedestrian trails built nearby and through the middle 
of occupied slickspots in the Boise Foothills are anticipated to impact 
individual plants and slickspot hydrology through trampling and spread 
of invasive nonnative plants in EO 38 near the Ada County Landfill 
(Cole 2008, p. 14). We have no other information to indicate that 
hiking or horseback riding have resulted in rangewide adverse impacts 
to L. papilliferum.
Summary of Recreation
    Although recreational use has the potential for some negative 
effects on Lepidium papilliferum, the evidence indicates that observed 
impacts to Lepidium papilliferum from hiking, cycling, and ORV use have 
been minimal, and are infrequent and localized. While there is one EO 
being impacted by cycling and pedestrian trails, there is no 
information indicating that other recreational activities are impacting 
the species throughout its range, or that recreational usage within EOs 
is expected to increase. Recreation does not appear to be a major 
factor impacting either L. papilliferum or its slickspot habitat, 
therefore we have determined that recreation represents a minor threat 
to the species.

Conclusion for Factor A

Rationale

    Based on the best scientific data currently available, the primary 
significant threats to Lepidium papilliferum are the effects of the 
modified wildfire regime and invasive nonnative plants, especially 
Bromus tectorum. These threats are impacting the quality and 
composition of the sagebrush-steppe ecosystem where L. papilliferum 
occurs, and are degrading the species' unique slickspot microsite 
habitats. These changes are associated with observed, significant 
decreases in the abundance of L. papilliferum. The observed increase in 
invasive annual grasses such as B. tectorum in the Great Basin, which 
includes the range of L. papilliferum, has resulted in increased 
frequency and extent of wildfires in L. papilliferum's native-sagebrush 
systems; fires that once naturally occurred every 100 years now occur 
on the order of every 5 years or less. The frequent return intervals of 
wildfire prevent the native sagebrush community from regenerating, and 
the habitat cannot achieve the late seral stage condition that 
represents high-quality habitat for L. papilliferum. The increased

[[Page 52043]]

frequency of wildfires also results in the reduction of native plant 
diversity and species richness, and invasive nonnative plant cover 
increases in the wake of fire. Not only is this increase in nonnative 
plants being observed in the surrounding sagebrush matrix, but 
nonnative plants are increasingly invading the formerly sparsely 
vegetated slickspots, resulting in competitive exclusion of L. 
papilliferum. The combination of wildfire and nonnative plants 
additionally impacts slickspots by damaging the microbiotic crust and 
increasing sedimentation and organic matter, which hinders germination 
of L. papilliferum. Slickspots possess unique edaphic and hydrological 
properties, and represent a limited habitat resource on the landscape. 
As L. papilliferum is adapted to the specialized properties of 
slickspots, the degradation of slickspots to the point that they no 
longer provide the essential functions that support L. papilliferum 
represents a permanent loss of habitat for the species.
    We have new information indicating a statistically significant 
negative association between the abundance of Lepidium papilliferum and 
wildfire, and a significant negative association between L. 
papilliferum abundance and percent cover of B. tectorum in the 
surrounding plant community; these negative associations are consistent 
throughout the range of the species. Wildfire occurs throughout the 
range of L. papilliferum and has dramatically increased in both 
frequency and extent, especially where B. tectorum is dominant. 
Furthermore, as B. tectorum and other nonnative annual grasses continue 
to spread and degrade the sagebrush-steppe ecosystem, we expect 
continued increases in fire frequency and magnitude, with associated 
negative impacts on L. papilliferum. As disturbances such as wildfire 
remove sagebrush and encourage the spread of nonnative annual grasses, 
we anticipate that the Owyhee harvester ant will expand into areas 
occupied by L. papilliferum, resulting in an increase in seed predation 
on L. papilliferum, with potential negative consequences for plant 
reproduction and the maintenance of the persistent seed bank (see 
Disease and Predation section below). Future development of the 
sagebrush-steppe habitat also threatens many of the remaining L. 
papilliferum sites, and is of particular concern in the Boise Foothills 
region, which supports the highest-density populations of L. 
papilliferum. Slickspots are relic Pleistocene formations and possess 
unique properties that likely cannot be recreated; slickspots lost to 
development represent a permanent loss of habitat for L. papilliferum.
    Given the observed negative association between the abundance of 
Lepidium papilliferum and the increased frequency of fire, as well as 
the demonstrated negative impacts of frequent, recurrent fire on the 
components that provide high-quality habitat for L. papilliferum, such 
as late seral stage sagebrush and high microbiotic crust cover, we 
consider the current wildfire regime to pose a significant and primary 
threat to L. papilliferum. Recurrent fire additionally promotes the 
continued invasion of nonnative annual grasses and other invasive 
nonnative plants. Given the observed negative association between the 
abundance of L. papilliferum and invasive nonnative plants both within 
slickspot microsites and in the surrounding plant community, the 
demonstrated ability of some nonnative plants to displace L. 
papilliferum from slickspots, the potential for nonnative grasses to 
facilitate the expansion of Owyhee harvester ants and thus increase 
seed predation on L. papilliferum, and the recognized contribution of 
nonnative plants such as B. tectorum to the increased fire frequency 
that poses a primary threat to the species, we consider invasive 
nonnative plants to pose a significant and primary threat to L. 
papilliferum as well. Although conservation measures have been 
implemented in an attempt to protect L. papilliferum and its habitat 
from these threats, at present the challenge of controlling and 
preventing the further spread of invasive nonnative plants and wildfire 
is too great for these measures to effectively reduce the degree of 
threat to the species across its range. Based on the demonstrated 
increases in nonnative plant cover in areas occupied by L. 
papilliferum, including slickspot microsites, the observed continuing 
increases in B. tectorum, observed increases in the frequency and 
extent of wildfires through the range of the species, and the lack of 
effective control mechanisms, we expect the degree of the threat from 
wildfire and invasive nonnative plant species to continue and likely 
increase within the foreseeable future.
    Development poses a somewhat lesser threat to the species. Although 
the impact of development can be severe, in that habitat conversion for 
residential, commercial, or agricultural development most often results 
in the permanent loss of slickspot habitat, the areas likely to be 
developed represent a relatively small portion of the species' range. 
The area most likely to be developed is, however, the area that 
supports some of the highest-density populations of Lepidium 
papilliferum. Other planned development projects, such as utility 
rights of way, can impact L. papilliferum by facilitating the increase 
of invasive nonnative plants and increasing the risk of human-caused 
wildfires, as well as through habitat fragmentation, isolation of 
populations, and potential reductions in insect pollinators. We 
consider development to pose a moderate degree of threat to Lepidium 
papilliferum, particularly for those populations in the Boise Foothills 
and the Snake River Plain physiographic regions.
    We additionally considered whether livestock use, wildfire 
management and post-wildfire rehabilitation, military training, or 
recreation pose a threat to Lepidium papilliferum through the present 
or threatened destruction, modification, or curtailment of its habitat 
or range. In the case of livestock use, the best available data 
indicate that although livestock have the potential to pose a threat to 
L. papilliferum, at present this threat appears to be seasonal and 
localized in nature. The continued maintenance of implemented 
conservation measures to protect L. papilliferum from inappropriate 
livestock use will be important in ameliorating the effects of this 
threat. We do not consider livestock use to pose a significant threat 
to the species at this time. The effects associated with wildfire 
management and post-wildfire rehabilitation, military training, and 
recreation are all positive or relatively minimal, and we do not 
consider any of these activities to pose a significant threat to L. 
papilliferum.

Determination for Factor A

    We have evaluated the best available scientific information on the 
present or threatened destruction, modification or curtailment of 
Lepidium papilliferum's habitat or range, and determined that this 
factor poses a significant threat to the viability of the species 
throughout its range, such that we anticipate L. papilliferum is likely 
to become an endangered species within the foreseeable future.
B. Overutilization for Commercial, Recreational, Scientific, or 
Educational Purposes
    We have no data indicating that overutilization for commercial, 
recreational, scientific, or educational purposes is a threat to 
Lepidium papilliferum.
C. Disease or Predation
    We have no data indicating that disease poses a threat to Lepidium

[[Page 52044]]

papilliferum. On the other hand, though insect and mammal herbivory do 
not appear to pose a threat to Lepidium papilliferum, seed predation by 
the Owyhee harvester ant may become a significant threat to the 
species.
    Insect herbivory of Lepidium papilliferum has been evaluated as 
part of pollinator and reproductive studies the past several years. The 
most abundant insect herbivore was a chrysomelid beetle, Phyllotreta 
sp., which chews holes in the flower's petals (Leavitt and Robertson 
2006, pp. 658-659). Lepidium papilliferum flowers suffering damage from 
Phyllotreta (a hole chewed in a single petal) have been documented to 
set seed at a significantly lower rate than undamaged flowers on the 
same plant. Overall, herbivory of L. papilliferum petals by chrysomelid 
beetles reduces the effectiveness of insect-mediated pollination, but 
does not physically inhibit pollination or seed production. The effect 
of herbivory by chrysomelid beetles appears to be limited in its impact 
on the species, and we do have not evidence suggesting that it poses a 
significant threat to L. papilliferum at this time.
    The Owyhee harvester ant was recently identified as a potentially 
important seed predator of Lepidium papilliferum. A study initiated in 
2006 found that following L. papilliferum's flowering season, Owyhee 
harvester ants remove the mature, seed-bearing fruits and return them 
to their nests outside of slickspots (Robertson and White 2007, pp. 8-
13). The researchers found that harvester ants can remove up to 90 
percent of L. papilliferum fruits and seeds, either directly from the 
plant or by scavenging seeds that drop to the ground (Robertson and 
White 2009, p. 9). Seventy-five percent of slickspots with flowering L. 
papilliferum located within 66 ft (20 m) of a harvester ant nest showed 
evidence of seed predation; the researchers suggest this is the maximum 
foraging distance for the Owyhee harvester ant (Robertson and White 
2009, p. 10). Slickspots with high densities of flowering L. 
papilliferum were also observed as more likely to show evidence of seed 
predation than those with low densities (Robertson and White 2007, p. 
13). Because harvester ants consume seeds of other plant species as 
well, most notably Bromus tectorum, L. papilliferum seeds are likely an 
opportunistic food item rather than an essential part of their diet 
(Robertson and White 2007, p. 12). Owyhee harvester ants have been 
observed bypassing seeds of B. tectorum in favor of L. papilliferum 
seeds (Robertson and White 2009, pers. comm.), but whether the seeds of 
L. papilliferum are preferred or may just be taken based on relatively 
greater seasonal availability is not yet known (Robertson 2009, pers. 
comm.).
    The Owyhee harvester ant is a species native to Southwest Idaho; 
therefore, it might be assumed that Lepidium papilliferum co-evolved 
with the ant and has adapted to adjust for the observed levels of seed 
predation. Evidence suggests, however, that harvester ant colonies were 
likely not numerous in the intact sagebrush-steppe habitat that has 
historically surrounded L. papilliferum in its slickspot microsites. 
White and Robertson (2008, p. 3) found that Owyhee harvester ant 
colonies are uniformly low in number in areas with high sagebrush 
cover, while densities are highest in the study areas with little 
sagebrush cover. By contrast, Owyhee harvester ant colonies range from 
uncommon to very common in areas dominated by annual grasses (Robertson 
and White 2009, p. 13), which would include Bromus tectorum. The study 
authors suggest that sites dominated by annual grasses but with low 
harvester ant numbers may represent areas that the ants have yet to 
colonize, or the habitat is unsuitable for reasons other than 
vegetation (Robertson and White 2009, p. 13). They further suggest that 
the observed shift from sagebrush to annual grasses may enable the ants 
to colonize areas that were historically not suitable for nesting, with 
potentially negative consequences for L. papilliferum (Robertson and 
White 2009, p. 13).
    Since Owyhee harvester ants are more common in disturbed areas with 
an abundance of B. tectorum (White and Robertson 2008, pp. 3-4), this 
raises a conservation concern for Lepidium papilliferum. As landscape 
disturbances such as wildfire are contributing to the loss or 
conversion of sagebrush habitats to annual grasslands, and these 
grasslands are likely to support higher densities of Owyhee harvester 
ants, these disturbances are likely contributing to an increase in the 
abundance and distribution of the harvester ants throughout L. 
papilliferum's geographic range. Furthermore, since these ants have 
been observed to harvest up to 90 percent of the seeds produced by L. 
papilliferum, increased predation by harvester ants, even at much lower 
levels than 90 percent, has the potential to significantly depress the 
reproductive capacity of the plant, as well as diminish the capacity to 
replenish the species seedbank. However, as this threat was only 
recently discovered, we have no information indicating what the actual 
magnitude or severity of this threat might be. In addition, no 
conservation measures have yet been attempted to ameliorate the threat 
of seed predation by the Owyhee harvester ant, and the researchers have 
urged caution in taking such measures until managers have a better 
understanding of the threat (Robertson and White 2009, p. 14).
    The OTA's ``Red Tie'' population of Lepidium papilliferum (EO 27) 
presents an interesting example of the potential threat posed by Owyhee 
harvester ants, and their apparent preferred association with grasses. 
Much of the Red Tie site is currently dominated by sagebrush (Artemisia 
tridentata ssp. tridentata), with L. papilliferum-occupied slickspots 
scattered throughout the sagebrush matrix. Currently, there is no 
evidence of contact between L. papilliferum and Owyhee harvester ants 
throughout most of the site where sagebrush dominates. The exception is 
at the periphery, where the vegetation transitions from sagebrush to a 
more open, grassland area. It was at this transition of habitat from 
sagebrush to grasslands where three active harvester ant colonies were 
found in 2008 (White and Robertson 2008, p. 4). The authors of this 
study caution that disturbances such as fire that remove sagebrush and 
promote the invasion of annual grasses may create conditions that 
promote the expansion of the harvester ants into areas currently 
occupied by L. papilliferum, resulting in increased seed predation 
throughout the range of the species (White and Robertson 2008, p. 4). 
Future HIP monitoring will examine proximity and density of Owyhee 
harvester ant colonies to L. papilliferum transects to track this 
potential new threat (Colket 2009, pers. comm.).
    Herbivory impacts to Lepidium papilliferum from large, native 
ungulates, such as elk, deer, and antelope, have not been observed. 
Statistical analyses of wild ungulate hoofprint cover in slickspots 
from 2004-2008 HIP monitoring data showed no relationship with L. 
papilliferum abundance (Sullivan and Nations 2009, p. 122). Sullivan 
and Nations (2009, p. 122) likewise found no association between the 
cover of livestock hoof prints and L. papilliferum abundance. Domestic 
cattle are not known to feed upon L. papilliferum, and domestic sheep 
have been observed pulling plants from the ground and spitting them out 
(Quinney and Weaver 1998, pers. comm.). Herbivory by large ungulates, 
whether wild or domestic, thus does not appear to pose a threat to L. 
papilliferum.

[[Page 52045]]

Summary of Disease or Predation
    Herbivory by chrysomelid beetles and by large ungulates, whether 
wild or domestic, does not appear to pose a significant threat to 
Lepidium papilliferum. Herbivory in the form of seed predation by 
Owyhee harvester ants, which was only recently discovered, appears to 
pose a potentially significant threat to the species. In one study, 
ants were observed to be capable of removing up to 90 percent of L. 
papilliferum fruits or seeds from slickspots within 66 ft (20 m) of a 
nest (Robertson and White 2009, p. 9). As the ants appear to favor the 
conditions created by the introduction of annual grasses, and the cover 
of annual grasses is expanding in L. papilliferum habitat, the increase 
in seed predation as a consequence of harvester ants moving into areas 
adjacent to occupied slickspots has the potential to significantly 
impact L. papilliferum recruitment and the replenishment of the seed 
bank. While this may be a minor threat at this point in time, given the 
projected increase in nonnative annual grasslands within the range of 
L. papilliferum and the apparent positive association between Owyhee 
harvester ants and grasslands, we believe this has the potential to 
become a significant threat to L. papilliferum in the foreseeable 
future.

Conclusion for Factor C

Rationale

    The effect of seed predation by Owyhee harvester ants is an 
emerging threat potentially affecting the long-term viability of 
Lepidium papilliferum. In areas where Owyhee harvester ants have become 
established, L. papilliferum could be depleted through lack of seedling 
recruitment. However, at this point in time we do not yet have enough 
research to determine whether the seed bank is being negatively 
affected by seed predation from harvester ants. The fact that harvester 
ant colonies appear to be found in higher numbers in annual grasslands, 
which are in turn increasing as the result of increased wildfire and 
the spread of nonnative grasses such as Bromus tectorum, suggests that 
the degree of this potential threat is likely to increase in the 
future. Our current understanding of how pervasive harvester ant 
colonies have become within the range of L. papilliferum, and their 
overall significance on the long-term viability of the species, is 
limited due to the short-term nature of the study results available 
thus far. The evidence suggests, however, that significant levels of 
seed predation associated with increased abundance and range of Owyhee 
harvester ants has the potential to pose a significant threat to L. 
papilliferum in the foreseeable future. This potential threat is 
pervasive throughout the range of L. papilliferum.

Determination for Factor C

    We have evaluated the best available scientific information on the 
effects of disease or predation on Lepidium papilliferum, and 
determined that this factor poses a significant threat to the viability 
of the species throughout its range, such that we anticipate that L. 
papilliferum is likely to become an endangered species within the 
foreseeable future, when we consider this factor in concert with the 
other factors impacting the species.
D. Inadequacy of Existing Regulatory Mechanisms
    Few existing regulatory mechanisms apply to Lepidium papilliferum. 
At the Federal level, Lepidium papilliferum is currently categorized as 
a Type 1 sensitive species by BLM (U.S. BLM 2003, p. 1; Rinkes 2009, 
pers. comm.). The BLM has regulations that address the need to protect 
sensitive, candidate, and federally listed species. The BLM is the 
primary land-management agency implementing conservation efforts for 
this species, and continues to monitor L. papilliferum on the Federal 
lands it manages.
    At the State level, Idaho Code 18-3911 protects a selected list of 
wildflowers, but Lepidium papilliferum is not one of the species 
listed. The protection allowed under Idaho Code 18-3911 basically makes 
it unlawful to export or offer for sale plants or parts of plants that 
are on the list of protected plants. As we have no information 
indicating that the export or sale of L. papilliferum poses a threat to 
the species, we do not consider the fact that L. papilliferum is not 
protected under Idaho Code 18-3911 to pose a significant threat to the 
species.

Conclusion for Factor D

Rationale

    The inadequacy of existing regulatory mechanisms does not appear to 
pose a threat to Lepidium papilliferum. The BLM manages L. papilliferum 
as a sensitive species, according to that agency's regulations, and 
continues to implement conservation efforts, as well as monitor the 
species, on lands under its management. Although the State of Idaho 
does not extend protections against export or sale to L. papilliferum 
under Idaho Code 18-3911, the lack of protection not appear to pose a 
significant threat to the species, as we have no information indicating 
that the species is subject to export or sale. However, we note that 
Idaho Code 18-3913 provides the Idaho Department of Fish and Game with 
authority to amend the list of protected wildflowers, so L. 
papilliferum could be protected as specified in Idaho Code 18-3911.

Determination for Factor D

    We have evaluated the best available information regarding the 
potential inadequacy of existing regulatory mechanisms and their effect 
on Lepidium papilliferum, and determined that this factor does not pose 
a significant threat to the viability of the species.
E. Other Natural or Manmade Factors Affecting Its Continued Existence

Precipitation Patterns

    Studies have indicated that the density and abundance of Lepidium 
papilliferum is positively correlated with levels of winter-spring 
(roughly January to March) precipitation (Palazzo et al. 2005, p. 9; 
Meyer et al. 2005, p. 15; Menke and Kaye 2006a, p. 8, 2006b pp. 10-11; 
CH2MHill 2007a, p. 14; Sullivan and Nations 2009, pp. 40-41), and 
negatively correlated with fall-winter (roughly October to December) 
precipitation (Meyer et al. 2005, pp. 15-16; Sullivan and Nations 2009, 
pp. 37-45). To assess the possibility that the negative trend in L. 
papilliferum density observed on the rough census plots at the OTA by 
Sullivan and Nations (2009, p. 39) may be due, at least in part, to 
either a corresponding negative trend in spring precipitation or a 
corresponding positive trend in winter precipitation at the OTA, we 
performed a least squares linear regression analysis (a statistical 
method to discern a potentially significant relationship between two 
variables, in this case whether there was any trend in rainfall over 
time) on monthly precipitation data available for the years 1991 
through 2007 (Zwartjes 2009). Similar to the simple linear model 
employed by Sullivan and Nations (2009, p. 38) in their analysis to 
assess whether there was any general, overall trend in population 
numbers over time, this exercise was intended only to determine whether 
there might have been any significant general trend in precipitation 
levels during the time period of interest, not to explain the 
potentially complex patterns of precipitation over time. According to 
the results, none of the precipitation parameters utilized (modeled to 
be consistent with those utilized by Sullivan and Nations 2009)--total 
annual precipitation, total precipitation for the spring months 
(analyzed in three

[[Page 52046]]

time blocks as the sum of precipitation in February through May, 
February through June, and March through May), total precipitation for 
the winter months (October through December), or monthly precipitation 
based on 3-month moving averages from January to March through December 
to February -- produced results suggesting that any of the 
precipitation trends over these years were significantly different 
statistically from a slope of zero (Zwartjes 2009, Figures 1-17, 
Appendix). Based on this simple model, there does not appear to be any 
general trend in precipitation over the years 1991 through 2007, either 
positive or negative, that corresponds with the observed negative trend 
in L. papilliferum density at the OTA over the years 1990 through 2008 
as identified by Sullivan and Nations (2009) (Zwartjes 2009, p. 1).
Summary of Precipitation Patterns
    The annual abundance of Lepidium papilliferum varies annually in 
concert with the level of precipitation; there appears to be a negative 
relationship between high winter precipitation and L. papilliferum 
abundance the following spring, and a positive relationship between 
spring precipitation and L. papilliferum abundance. One possible 
explanation for the observed significant decline in L. papilliferum 
abundance over time at the OTA rough census areas is that there was a 
similar trend in precipitation over that same time period (a decrease 
in spring precipitation, an increase in winter precipitation, or both). 
We did not, however, find any significant trend in precipitation in the 
same time frame. Thus, any changes in the abundance or density of L. 
papilliferum appear to have occurred independently of any trend in 
precipitation. Therefore, similar to our 2007 finding, we do not 
consider the current precipitation pattern to pose an extinction risk 
to the species.

Habitat Fragmentation and Isolation of Small Populations

    Due to its occupancy of patchily distributed slickspots, the 
habitat of Lepidium papilliferum is somewhat naturally fragmented. 
Fragmentation at a larger scale, however, can pose problems for L. 
papilliferum by creating barriers in the landscape that prevent 
effective genetic exchange between populations. Seed dispersal for L. 
papilliferum likely occurs only over very short distances; thus, 
pollinators and pollen dispersal are the primary means for reproductive 
and genetic exchange between L. papilliferum sites (Robertson and 
Ulappa 2004, pp. 1705, 1708; Stillman et al. 2005, pp. 1, 6-8). 
Research indicates that seeds generated by the pollination of nearby 
plants have reduced viability, and that L. papilliferum seed viability 
increases as the distance to the contributing pollination source 
increases (Robertson and Ulappa 2004, pp 1705, 1708). The ability to 
exchange pollen with distant populations is therefore an advantage for 
L. papilliferum. Barriers or too much distance between slickspots and 
pollinating insect habitats can reduce the effective range of insects 
important to L. papilliferum pollination (Robertson et al. 2004, pp. 2-
4). Barriers can include agricultural fields, urban development, and 
large areas of annual and perennial grass monocultures that do not 
support diversity and suitable floral resources such as nectar or 
edible pollen for pollinators. Lepidium papilliferum habitats separated 
by distances greater than the effective range of available pollinating 
insects are at a genetic disadvantage, and may become vulnerable to the 
effects of loss of genetic diversity (Stillman et al. 2005, pp. 1, 6-8) 
and a reduction in seed production (Robertson et al. 2004, p. 1705). A 
genetic analysis of L. papilliferum suggested that populations in the 
Snake River Plain and the Owyhee Plateau ``may have reduced genetic 
diversity'' (Larson et al. 2006, p. 17; note the Boise Foothills were 
not analyzed separately in this study).
    Many of the remaining occurrences of Lepidium papilliferum, 
particularly in the Snake River Plain near urban centers, are 
restricted to small, remnant patches of suitable sagebrush-steppe 
habitat. When last surveyed, 31 EOs (37 percent) each had fewer than 50 
plants (Colket et al. 2006, Tables 1 to 13). Many of these small 
remnant EOs exist within habitat that is degraded by the factors 
identified above. Small L. papilliferum populations have likely 
persisted due to their long-lived seed bank, but the potential risk of 
depletion of each population's seed bank with no new genetic input 
makes the persistence of these small populations uncertain. Providing 
suitable habitats and foraging habitats for the species' insect 
pollinators is important for maintaining L. papilliferum genetic 
diversity. Small populations are vulnerable to relatively minor 
environmental disturbances such as wildfire, herbicide drift, and 
nonnative plant invasions (Given 1994, pp. 66-67), and are subject to 
the loss of genetic diversity from genetic drift and inbreeding 
(Ellstrand and Elam 1993, pp. 217-237). Populations with lowered 
genetic diversity are more prone to local extinction (Barrett and Kohn 
1991, pp. 4, 28). Smaller populations generally have lower genetic 
diversity, and lower genetic diversity may in turn lead to even smaller 
populations by decreasing the species' ability to adapt, thereby 
increasing the probability of population extinction (Newman and Pilson 
1997, p. 360).
    Fragmentation (either by development or wildfires) has occurred in 
62 of the 79 EOs for which habitat information is known (15 of 16 on 
the Boise Foothills, 35 of 42 on the Snake River Plain and 12 of 21 on 
the Owyhee Plateau), and 78 EOs (all except one on the Owyhee Plateau) 
have fragmentation occurring within 0.31 mi (500 m) of the EOs (Cole 
2009b, Threats Table). Additionally, as described above in Factor A, 
Development, several development projects are planned within the 
occupied range of Lepidium papilliferum that would contribute to 
further large-scale fragmentation of its habitat, potentially resulting 
in decreased viability of populations through decreased seed 
production, reduced genetic diversity, and the increased inherent 
vulnerability of small populations to localized extirpation.

Summary of Habitat Fragmentation and Isolation of Small Populations

    Even though Lepidium papilliferum occurs in naturally patchy 
microsite habitats, the increasing degree of fragmentation produced by 
wildfires and development may result in the separation of populations 
beyond the distance that its insect pollinators are capable of 
traveling. Genetic exchange in L. papilliferum is achieved through 
either seed dispersal or insect-mediated pollination, and plants that 
receive pollen from more distant sources demonstrate greater 
reproductive success in terms of seed production. As all indications 
are that seeds are dispersed over only a very small distance and insect 
pollinators are also limited in their dispersal capabilities, habitat 
fragmentation and isolation of populations poses a threat to L. 
papilliferum in terms of decreased reproductive success (lower seed 
set), reduced genetic variability, and greater local extinction risk. 
For these reasons we consider habitat fragmentation resulting from 
wildfires and development to pose a moderate degree of threat to 
Lepidium papilliferum. We consider this threat to be significant, but 
not as severe as the threats posed by the modified wildfire regime and 
invasive nonnative plant species. The threat of habitat fragmentation 
and isolation of small populations is pervasive throughout the range of 
L. papilliferum.

[[Page 52047]]

Climate Change

    The Intergovernmental Panel on Climate Change (IPCC) was 
established in 1988 by the World Meteorological Organization and the 
United Nations Environment Program in response to growing concerns 
about climate change and, in particular, the effects of global warming. 
Although the extent of warming likely to occur is not known with 
certainty at this time, the IPCC has concluded that warming of the 
climate is unequivocal, and that continued greenhouse gas emissions at 
or above current rates will cause further warming (IPCC 2007, p. 30). 
Eleven of the 12 years from 1995 through 2006 rank among the 12 warmest 
years in the instrumental record of global surface temperature since 
1850 (ISAB 2007). Climate-change scenarios estimate that the mean air 
temperature could increase by over 3 degrees Celsius (5.4 degrees 
Fahrenheit) by 2100 (IPCC 2007, p. 46). The IPCC also projects that 
there will very likely be regional increases in the frequency of hot 
extremes, heat waves, and heavy precipitation (IPCC 2007, p. 46), as 
well as increases in atmospheric carbon dioxide (IPCC 2007, p. 36).
    We recognize that there are scientific differences of opinion on 
many aspects of climate change, including the role of natural 
variability in climate. In our analysis, we rely primarily on synthesis 
documents (e.g., IPCC 2007, Karl et al. 2009) that present the 
consensus view of a very large number of experts on climate change from 
around the world. We have found that these synthesis reports, as well 
as the scientific papers used in those reports or resulting from those 
reports, represent the best available scientific information we can use 
to inform our decision and have relied upon them and provided citation 
within our analysis. In addition, where possible we have utilized 
projections specific to the region of interest, the Great Basin, which 
includes the range of Lepidium papilliferum.
    Projected climate change and its associated consequences have the 
potential to affect Lepidium papilliferum and may increase its risk of 
extinction, as the impacts of climate change interact with other 
stressors such as habitat degradation and loss that are already 
affecting the species (Karl et al. 2009, p. 81). In the Pacific 
Northwest, regionally averaged temperatures have risen 0.8 degrees 
Celsius (1.5 degrees Fahrenheit) over the last century (as much as 2 
degrees Celsius (4 degrees Fahrenheit) in some areas), and are 
projected to increase by another 1.5 to 5.5 degrees Celsius (3 to 10 
degrees Fahrenheit) over the next 100 years (Mote et al. 2003, p. 54; 
Karl et al. 2009, p. 135). Arid regions such as the Great Basin where 
L. papilliferum occurs are likely to become hotter and drier; fire 
frequency is expected to accelerate, and fires may become larger and 
more severe (Brown et al. 2004, pp. 382-383; Neilson et al. 2005, p. 
150; Chambers and Pellant 2008, p. 31; Karl et al. 2009, p. 83). Under 
projected future temperature conditions, the cover of sagebrush in the 
Great Basin region is anticipated to be dramatically reduced (Neilson 
et al. 2005, p. 154). Warmer temperatures and greater concentrations of 
atmospheric carbon dioxide create conditions favorable to Bromus 
tectorum, as described below, thus continuing the positive feedback 
cycle between the invasive annual grass and fire frequency that poses a 
significant threat to L. papilliferum (Chambers and Pellant 2008, p. 
32; Karl et al. 2009, p. 83).
    Emissions of carbon dioxide, considered to be the most important 
anthropogenic greenhouse gas, increased due to human activities by 
approximately 80 percent between 1970 and 2004 (IPCC 2007, p. 36). 
Future carbon dioxide emissions from energy use are projected to 
increase by 40 to 110 percent over the next few decades, between 2000 
and 2030 (IPCC 2007, p. 44). An increase in the atmospheric 
concentration of carbon dioxide has important implications for Lepidium 
papilliferum, beyond those associated with warming temperatures, 
because higher concentrations of carbon dioxide are favorable for the 
growth and productivity of Bromus tectorum (Smith et al. 1987, p. 142; 
Smith et al. 2000, p. 81). Although most plants respond positively to 
increased carbon dioxide levels, many invasive nonnative plants respond 
with greater growth rates than native plants, including B. tectorum 
(Smith et al. 1987, p. 142; Smith et al. 2000, p. 81; Karl et al. 2009, 
p. 83). Laboratory research results illustrated that B. tectorum grown 
at carbon dioxide levels representative of current climatic conditions 
matured more quickly, produced more seed and greater biomass, and 
produced significantly more heat per unit biomass when burned than B. 
tectorum grown at ``pre-industrial'' carbon dioxide levels (Blank et 
al. 2006, pp. 231, 234). These responses to increasing carbon dioxide 
may have increased the flammability in B. tectorum communities during 
the past century (Ziska et al. 2005, as cited in Zouhar et al. 2008, p. 
30; Blank et al. 2006, p. 234).
    Field studies likewise demonstrate that Bromus species demonstrate 
significantly higher plant density, biomass, and seed rain (dispersed 
seeds) at elevated carbon dioxide levels relative to native annuals 
(Smith et al. 2000, pp. 79-81). The researchers conclude that ``the 
results from this study * * * confirm experimentally in an intact 
ecosystem that elevated carbon dioxide may enhance the invasive success 
of Bromus spp. in arid ecosystems,'' and suggest that this enhanced 
success will then expose these areas to accelerated fire cycles (Smith 
et al. 2000, p. 81). Chambers and Pellant (2008, p. 32) also suggest 
that higher carbon dioxide levels are likely increasing B. tectorum 
fuel loads due to increased productivity, with a resulting increase in 
fire frequency and extent. Based on the best available information, we 
therefore expect continuing production of atmospheric carbon dioxide at 
or above current levels, as predicted, to increase the threat posed to 
L. papilliferum by B. tectorum and from more frequent, expansive, and 
severe wildfires (Smith et al. 1987, p. 143; Smith et al. 2000, p. 81; 
Brown et al. 2004, p. 384; Neilson et al. 2005, pp. 150, 156; Chambers 
and Pellant 2008, pp. 31-32).
    Bradley et al. (in press, pp. 1-11) predict that nonnative invasive 
species in the sagebrush-steppe ecosystem may either expand or contract 
under climate change, depending on the current and projected future 
range of a particular invasive plant species. They developed a 
bioclimatic model for Bromus tectorum based on maps of invaded range 
derived from remote sensing and on the climate variables that best 
predict species presence, and found that the best predictors of B. 
tectorum occurrence are summer, annual, and spring precipitation, 
followed by winter temperature (Bradley et al., in press, p. 5). They 
then used projections of 10 atmosphere-ocean, general-circulation 
models for the year 2100. Depending primarily on future precipitation 
conditions, the model predicts B. tectorum is likely to shift 
northwards, leading to expanded risk of B. tectorum invasion in Idaho, 
Montana, and Wyoming, but reduced risk of invasion in southern Nevada 
and Utah, which currently have large areas dominated by this nonnative 
grass (Bradley et al., in press, p. 5). Although the authors note that 
their models also predict some range contractions by B. tectorum by 
2100, much of southern Idaho where Lepidium papilliferum occurs appears 
to maintain large populations of B. tectorum (Figure 4, p. 7). The 
threat posed to L. papilliferum by the greater frequency and geographic 
extent of wildfires and other associated negative

[[Page 52048]]

impacts from the presence of B. tectorum is therefore expected to 
continue into the foreseeable future.
    An additional potential threat to Lepidium papilliferum resulting 
from climate change is the predicted change in precipitation patterns. 
Current projections for the Pacific Northwest region are that 
precipitation will increase in the winter but decrease in the summer 
months (Karl et al. 2009, p. 135). The survivorship of L. papilliferum 
rosettes to flower the following spring is favored by greater summer 
precipitation (Meyer et al. 2005, p. 15; CH2MHill 2007a, p. 14; 
Sullivan and Nations 2009, pp. 33, 41), and increased winter 
precipitation appears to decrease survivorship (Meyer et al. 2005, pp. 
15-16; Sullivan and Nations 2009, pp. 39, 43-44). As the projected 
rainfall pattern under climate change would follow the opposite 
pattern, this alteration in seasonal precipitation could result in 
decreased survivorship of L. papilliferum. Alterations in precipitation 
patterns, however, are more uncertain than predicted changes in 
temperature for the Great Basin region (Neilson et al. 2005, p. 153).
Summary of Climate Change
    The direct, long-term impact from climate change to Lepidium 
papilliferum is yet to be determined. However, as described under 
Factor A, above, the invasion of Bromus tectorum and the associated 
changes in fire regime currently pose one of the most significant 
threats to Lepidium papilliferum, the sagebrush-steppe ecosystem, and 
the slickspot habitats where L. papilliferum resides. Under current 
climate-change projections, we anticipate that future climatic 
conditions will favor further invasion by B. tectorum, that fire 
frequency will continue to increase, and the extent and severity of 
fires may increase as well. Precipitation patterns may also be altered 
as a result of climate change, resulting in potential decreased 
survivorship of L. papilliferum, although the projections for future 
precipitation patterns are less certain. The consequences of climate 
change, if current projections are realized, are therefore likely to 
exacerbate the existing primary threats to L. papilliferum of frequent 
wildfire and invasive nonnative plants, particularly B. tectorum. As 
the IPCC projects that the changes to the global climate system in the 
21st century will likely be greater than those observed in the 20th 
century (IPCC 2007, p. 45), we anticipate that these effects will 
continue and likely increase into the foreseeable future. As there is 
some degree of uncertainty regarding the potential effects of climate 
change on L. papilliferum specifically, climate change in and of itself 
was not considered a significant factor in our determination to list L. 
papilliferum as a threatened species. However, we recognize that the 
severity and scope of the primary threats to L. papilliferum of 
frequent wildfire and B. tectorum are likely to magnify depending on 
the realized outcome of climate change within the foreseeable future; 
thus, we consider climate change as playing a potentially important 
supporting role in intensifying the primary current threats to the 
species.

Conclusion for Factor E

Rationale

    Habitat fragmentation that results from wildfires and development 
may result in the separation of Lepidium papilliferum populations 
beyond the distance that its insect pollinators can travel, and likely 
limits the ability for seeds to travel between populations as well. 
Limited genetic exchange due to fragmentation can result in reduced 
seed production for this species, as well as a loss of genetic 
diversity. Small, isolated populations with lowered genetic diversity 
are at increased risk of local extinction. Habitat fragmentation due to 
wildfires and various forms of development is occurring throughout the 
range of the species, and is expected to increase in the future. As the 
insect pollinators of L. papilliferum traverse relatively short 
distances, and evidence suggests that seed dispersal is limited as 
well, we consider the consequences of limited genetic exchange as a 
result of habitat fragmentation to pose a significant and moderate 
degree of threat to L. papilliferum throughout its range. Although 
significant, we do not consider the severity of this threat to reach 
the level of threat posed to L. papilliferum by the primary threats of 
the modified wildfire regime and invasive nonnative plant species.
    Current climate-change models predict future climatic conditions 
within the range of Lepidium papilliferum will favor further invasion 
by Bromus tectorum. These models also project that fire frequency will 
continue to increase and that the extent and severity of wildfires may 
increase as well. Thus, the consequences of projected, future climate 
change, if realized, are likely to further magnify the severity and 
scope of the primary significant threats to L. papilliferum. Due to the 
uncertainty associated with climate change projections, we do not 
consider climate change in and of itself to represent a significant 
threat to L. papilliferum. However, we acknowledge that climate change 
will likely play a potentially important supporting role in 
intensifying the most significant current threats to the species in the 
foreseeable future. The projected consequences of climate change would 
act to exacerbate the primary threats of frequent wildfire and invasive 
nonnative plant species to L. papilliferum throughout its range.
    The abundance of Lepidium papilliferum is closely associated with 
levels of rainfall, showing a positive association with high levels of 
spring precipitation and a negative association with high levels of 
winter precipitation. We thus considered whether the declining 
population trend in L. papilliferum might be a consequence of a 
corresponding trend in precipitation. We did not find evidence of any 
trend in precipitation for L. papilliferum for the time period for 
which we have evidence of the declining trend in density at the OTA; 
thus, we conclude that any population trend in L. papilliferum is 
independent of any trend in precipitation. Precipitation patterns were 
therefore not considered to pose a threat to the species.

Determination for Factor E

    We have evaluated the best available scientific information on 
other natural or manmade factors affecting the continued existence of 
Lepidium papilliferum, including precipitation patterns, habitat 
fragmentation and isolation of small populations, and climate change, 
and determined that this factor poses a significant threat to the 
viability of the species throughout its range when considered in 
concert with Factor A, such that we anticipate that L. papilliferum is 
likely to become an endangered species within the foreseeable future.

Evaluation of Conservation Efforts

    In making a determination as to whether any species is an 
endangered species or a threatened species, Section 4(b)(1)(A) of the 
Act mandates that the Secretary shall make such determinations ``solely 
on the basis of the best scientific and commercial data available to 
him after conducting a review of the status of the species and after 
taking into account those efforts, if any, being made by any State or 
foreign nation, or any political subdivision of a State or foreign 
nation, to protect such species.'' Here, we describe and evaluate those 
conservation efforts being made by the State of Idaho and other 
entities to protect Lepidium papilliferum; we also consider 
conservation efforts that are formally

[[Page 52049]]

planned but have not yet been implemented, as per the Service's Policy 
for the Evaluation of Conservation Efforts (68 FR 15100; March 28, 
2003). These conservation efforts were briefly described in our earlier 
evaluation of the threat factors affecting the species. Here we present 
a single summary of the conservation efforts implemented or planned for 
the benefit of L. papilliferum, which we considered in the course of 
our listing determination. Any management actions that were only 
planned at the time of our withdrawal of the proposal to list Lepidium 
papilliferum in 2007 (72 FR 1622; January 12, 2007) but have since been 
implemented were considered in our evaluation of ongoing conservation 
efforts in this rule.
Ongoing Conservation Efforts
    Currently, there are four formalized plans that contain 
conservation measures for Lepidium papilliferum. The four plans 
include: (1) the CCA for Slickspot Peppergrass with the State of Idaho, 
BLM, Idaho Army National Guard, and nongovernmental cooperators 
(private landowners who also hold livestock grazing permits on BLM 
lands) (State of Idaho et al. 2003, 2006); (2) the Idaho Army National 
Guard Integrated Natural Resource Management Plan for Gowen Field/
Orchard Training Area (IDARNG 2004); (3) the U.S. Air Force Integrated 
Natural Resource Management Plan for the Juniper Butte Range (Mountain 
Home Air Force Base) (U.S. Air Force 2004); and (4) the Conservation 
Agreement for Slickspot Peppergrass (Lepidium papilliferum) at the 
Boise Airport, Ada County, Idaho (Boise Airport 2003). A fifth plan 
that expired in October of 2006 is a Conservation Agreement by, and 
between, Boise City and the U.S. Fish and Wildlife Service for Allium 
aasea (Aase's onion), Astragalus mulfordiae (Mulford's milkvetch) and 
L. papilliferum (Hull's Gulch Agreement) (U.S. Fish and Wildlife 
Service 1996). A new agreement is currently being crafted to update the 
expired agreement and will include conservation measures for portions 
of four small L. papilliferum EOs in the Boise Foothills region on 
lands administered by both the City of Boise and Ada County. This new 
agreement is expected to be completed by September of 2009.
    The majority of the individual conservation efforts being 
implemented for Lepidium papilliferum are contained in the State of 
Idaho CCA, which was originally drafted in 2003, and updated in 2006; 
it is scheduled to expire in 2013. The CCA represents an important 
milestone in the cooperative conservation of Lepidium papilliferum 
given its rangewide scope and coordinated management across Federal and 
State of Idaho managed lands. The CCA includes rangewide efforts that 
are intended to address the need to: Maintain and enhance L. 
papilliferum habitat; reduce intensity, frequency, and size of natural- 
and human-caused wildfires; minimize loss of habitat associated with 
wildfire-suppression activities; reduce the potential for invasion of 
nonnative plant species from wildfire; minimize the loss of habitat 
associated with rehabilitation and restoration techniques; minimize the 
establishment of invasive nonnative species; minimize the degradation 
or loss of habitat from ORV use; mitigate the negative effects of 
military training and other associated activities on the OTA; and 
minimize the impact of ground disturbances caused by livestock 
penetrating trampling during periods when soils are saturated.
    As a signatory of the CCA (State of Idaho et al. 2003, 2006), the 
BLM is the primary land management agency implementing conservation 
efforts for Lepidium papilliferum on their lands. Implementation of the 
conservation measures in the CCA represents a major commitment on 
behalf of the BLM, which has management authority for the majority of 
the range where L. papilliferum occurs (i.e., 87 percent of the total 
EO area (13,470 ac (5,451 ha)) and portions of 69 of the 80 extant 
EOs). Conservation measures for ongoing activities from the CCA that 
were appropriate for land-use plan programs were included in an August 
22, 2006, Conservation Agreement between the Service and the BLM to 
avoid or minimize impacts to L. papilliferum during the BLM's 
implementation of existing land-use plans. This Conservation Agreement 
between Idaho BLM and the Service is scheduled to expire on December 
31, 2010, at which time it may be reviewed for renewal or expiration.
    Until recently, the CCA also represented an effort by 
nongovernmental cooperators (private landowners who also hold BLM 
livestock grazing permits) for the conservation of Lepidium 
papilliferum on private lands. Six Memoranda of Understanding (MOUs) 
between nongovernmental cooperators and the State of Idaho for 
conservation of L. papilliferum on private lands were in place from 
2004 through December 2007. We are not aware that these MOUs have been 
reissued at this time. The size and habitat condition of L. 
papilliferum locations on these private lands are also unknown to the 
Service. The MOUs included 17,045 ac (6,898 ha) of private lands; 
however, less than 2 percent of the currently known area occupied by L. 
papilliferum (260 ac (105 ha)) is documented as occurring on private 
lands.
    Although a majority of the conservation measures identified in the 
CCA have been implemented to date, relatively few have been determined 
at this time to be measurably effective for conserving Lepidium 
papilliferum. For example, many of the implemented measures are 
conducting surveys, monitoring, or providing for public outreach and 
education, which have limited direct or long-term conservation benefits 
to the species. With the exception of several conservation efforts 
implemented at the OTA that have been successful in controlling the 
effects of wildfire on L. papilliferum habitats, many of the remaining 
conservation efforts and adaptive management provisions identified in 
the CCA have not been implemented over a long enough period of time to 
have sufficient certainty they can be effective in reducing threats. 
Furthermore, the conservation measures identified in the CCA are 
concentrated on L. papilliferum EOs. While this is helpful, the 
effective control of the most significant threats to L. papilliferum, 
wildfire and invasive nonnative plant species, requires efforts that 
extend well beyond the boundaries of the EOs, since by their nature 
these are expansive threats that occur throughout the Great Basin. We 
recognize the conservation efforts identified in the CCA as having a 
conservation benefit for L. papilliferum, but rangewide their 
effectiveness in reducing or eliminating the most significant threats 
has not been demonstrated at this time.
    The IDARNG, another signatory to the CCA, also implements 
conservation efforts for Lepidium papilliferum on the OTA through its 
INRMP (IDARNG 2004, Chapter 4.4.2). The IDARNG's OTA contains 7,213 ac 
(2,919 ha) of occupied L. papilliferum habitat, 7,163 ac (2,899 ha) of 
which represents some of the highest-quality occupied L. papilliferum 
habitat in the Snake River Plain region. Many of the conservation 
efforts, such as prohibiting military training activities within areas 
reserved for conservation of L. papilliferum, have been implemented by 
the IDARNG for more than 18 years and have been demonstrated to be 
effective in minimizing military training impacts to the species. The 
INRMP for the OTA expired in September 2008, and is currently being 
updated (Quinney 2008, pers. comm.).

[[Page 52050]]

    The U.S. Air Force's INRMP completed in 2004 includes conservation 
efforts for Lepidium papilliferum. The U.S. Air Force manages 2,028 ac 
(810 ha) of occupied L. papilliferum habitat within the Juniper Butte 
Range in the Owyhee Plateau region. The INRMP contains specific 
measures developed to minimize the impacts from military training and 
the associated indirect effects from wildfire, nonnative invasive 
weeds, and livestock use on L. papilliferum. For example, the U.S. Air 
Force has a number of ongoing efforts to address wildfire suppression 
on the entire 11,500 ac (4,800 ha) Juniper Butte Range. The U.S. Air 
Force addresses wildfire prevention through reducing standing fuels and 
weeds, planting fire-resistant vegetation in areas with a higher 
potential for ignition sources such as along roads, and using wildfire 
indices to determine when to restrict military activities when the 
wildfire hazard rating is extreme (U.S. Air Force 2004, p. 6-55). As a 
result, the threat from wildfire to L. papilliferum associated with 
U.S. Air Force training activities is expected to be reduced within the 
Juniper Butte Range. The INRMP that includes the Juniper Butte Range is 
scheduled to expire in 2009 and is currently being updated (EES 2008).
    A Conservation Agreement between the Service and the City of Boise 
Airport was completed in 2003 for the conservation of two Lepidium 
papilliferum EOs located on the southern portion of Boise Airport lands 
(Boise Airport 2003). Using the latest Idaho Natural Heritage Program 
L. papilliferum EO ranks, these two EOs include a C-ranked site (2.8 ac 
(1.2 ha)) and a D-ranked site (0.5 ac (0.2 ha)), with low documented 
plant numbers and very poor habitat condition (Colket et al. 2006, 
Appendix C). Both EOs included in this Conservation Agreement are also 
susceptible to impacts from invasive nonnative weeds and wildfire. The 
primary conservation actions identified in this agreement included the 
construction of fuel breaks around L. papilliferum populations, the 
preclusion of livestock use, minimizing the use of herbicides, and 
signing areas to prevent access. We have not received documentation of 
implementation or effectiveness of the conservation efforts identified 
in this Conservation Agreement. This agreement is scheduled to expire 
in December 2015. We acknowledge the positive conservation intent of 
this agreement, and although the status of the efforts are unknown, 
even if they were known to be implemented and effective, the area 
covered by the City of Boise Conservation Agreement is so small that it 
would have little effect on our ultimate finding in this rule.
Planned Conservation Efforts
    Prior to our 2007 withdrawal notice (72 FR 1622; January 12, 2007), 
we reviewed the available information for all of the individual 
conservation efforts contained in five conservation plans developed for 
Lepidium papilliferum (State of Idaho CCA, IDARNG INRMP, U.S. Air Force 
INRMP, Boise Airport CA, and Hull's Gulch Agreement) to evaluate how 
many were implemented or certain to be implemented in the future; and 
how many efforts were so effective as to have contributed to the 
elimination or reduction of one or more threats to the species. Based 
upon our review at that time, we determined that 373 of the nearly 600 
individual conservation efforts identified in the 5 plans were 
currently implemented and that 35 of these efforts were determined to 
be both certain to be implemented and effective in reducing threats to 
L. papilliferum or were already known to be implemented and effective 
in reducing threats to the species. Since that time, we have received 
additional information from the implementing agencies that describe the 
status of at least 152 conservation measures included in 3 of the 5 
conservation plans (State of Idaho CCA, IDARNG INRMP, and US Air Force 
INRMP) that were implemented in 2007 and 2008 (CH2MHill 2007a, p. 16; 
CH2MHill 2007b, pp. 1-6; Quinney 2007 pp.1-3; USBLM 2007, p. 2-4; 
CH2MHill 2008a, p. 17; CH2MHill 2008b, pp. 1-6; Quinney 2008 pp.1-3; 
USBLM 2008a, pp. 2-38; USBLM 2008c, pp. 1-15; Colket 2009, pp. 65-72). 
We have not received specific information regarding conservation 
measures contained in the Boise Airport conservation agreement that 
have been implemented, or how effective these measures have been in 
reducing threats to L. papilliferum for 2007 or 2008. The fifth 
conservation plan, the Hull's Gulch Agreement between Boise City and 
the Service, expired in October 2006 and has yet to be renewed.
    Our latest evaluation of planned future conservation efforts, 
taking into consideration the most recent information provided by the 
implementing agencies, again concludes that 35 out of roughly 600 
individual management actions identified in the 5 formalized 
conservation plans for Lepidium papilliferum are certain to be 
implemented and effective. However, these 35 conservation efforts 
determined to be implemented and effective are from the CCA, Air Force 
INRMP and OTA INRMP, and are not applicable rangewide. For example, 20 
of the 35 conservation efforts are primarily directed at conserving L. 
papilliferum at 1 of 3 EOs located on the OTA. Therefore, these 35 
measures would not prevent the species from becoming endangered in the 
foreseeable future either rangewide or on a significant portion of the 
species' range. We thus do not consider these 35 actions sufficient to 
offset the threats posed to L. papilliferum across its range by the 
modified wildfire regime; invasive nonnative plants; development; 
potential seed predation by harvester ants; and habitat fragmentation 
and isolation, to the point that we would consider it unlikely that L. 
papilliferum will become endangered within the foreseeable future.
Summary of Ongoing and Planned Conservation Efforts
    We recognize the long list of ongoing and proposed conservation 
efforts by the State of Idaho, IDARNG, U.S. Air Force, and other non-
governmental cooperators being put forth to conserve Lepidium 
papilliferum. All parties should be commended for their conservation 
efforts. Our review of conservation efforts indicates that not all of 
the measures identified in the conservation plans have been implemented 
and most have not been demonstrated at this time to effectively reduce 
or eliminate the most significant threats to the species. Many of these 
conservation efforts are limited in their ability to effectively reduce 
the long-term habitat degradation and destruction occurring within the 
sagebrush-steppe ecosystem and L. papilliferum habitats across the 
range of the species from the effects of a changed wildfire regime and 
nonnative plant invasions, in addition to other threats. In many cases, 
effective control measures for these threats are not yet known, 
financially or technically feasible, or logistically possible to 
implement on the scale that would be necessary to successfully 
ameliorate the threat throughout the range of L. papilliferum. Although 
the ongoing conservation efforts demonstrated to be effective are a 
positive step toward the conservation of L. papilliferum, and a few, 
such as those designed to reduce the impact of ground disturbances 
caused by livestock when soils are saturated in the spring, described 
under Livestock Use, above, have likely reduced the severity of some 
threats to the species, on the whole we find that the conservation 
efforts in place at this

[[Page 52051]]

time are not sufficient to offset the degree of threat posed to the 
species by the modified wildfire regime; invasive nonnative plants; 
development; potential seed predation by harvester ants; and habitat 
fragmentation and isolation, to the point that we would consider it 
unlikely that L. papilliferum will become endangered within the 
foreseeable future.
    We have also considered all formally planned conservation efforts, 
by evaluating the individual conservation efforts contained in five 
conservation plans developed for Lepidium papilliferum to evaluate how 
many were implemented or certain to be implemented in the future; and 
how many efforts were so effective as to have contributed to the 
elimination or reduction of one or more threats to the species. We have 
no information indicating that there are any new conservation efforts 
planned for the future that we have not already evaluated in the course 
of applying our Policy for the Evaluation of Conservation Efforts (68 
FR 15100; March 28, 2003) to management actions planned for the benefit 
of L. papilliferum, as described in past actions for this species (69 
FR 3094; 72 FR 1622). We recognize the benefit of these planned 
conservation measures and acknowledge the efforts of the entities 
engaged in planning these measures for the benefit of L. papilliferum. 
However, as with ongoing conservation efforts, in most cases the 
measures are simply not logistically feasible for implementation at the 
scale that would be required to effectively reduce the threats to the 
species across its range. Based on our most recent evaluation, we 
conclude that those planned conservations efforts that we consider 
likely to be implemented and effective are not sufficient to offset the 
threats posed to L. papilliferum by the modified wildfire regime; 
invasive nonnative plants; development; potential seed predation by 
harvester ants; and habitat fragmentation and isolation, to the point 
that we would consider it unlikely that L. papilliferum will become 
endangered within the foreseeable future.
    In summary, all ongoing conservation efforts have been considered 
and evaluated in terms of their effectiveness in ameliorating the 
threats to Lepidium papilliferum as described in this rule. We have 
additionally considered all formally planned future conservation 
efforts for the species, and evaluated those efforts in terms of the 
certainty of their implementation and their potential for effectiveness 
in ameliorating the threats to L. papilliferum. We recognize and 
acknowledge the efforts of the many entities participating in 
conservation efforts for the protection of L. papilliferum. However, 
our evaluation of the ongoing and planned conservation efforts for the 
species concludes that these efforts are not sufficient to offset the 
threats described in this rule to the point that we consider it 
unlikely that L. papilliferum will become endangered within the 
foreseeable future.

Finding

    We have carefully assessed the best scientific and commercial 
information available regarding the present and future threats to 
Lepidium papilliferum. This plant is endemic to southwest Idaho and 
occurs within a limited geographical range that totals approximately 
16,000 ac (6,475 ha). The species predominantly occurs in highly 
specialized and unique microsite habitats called slickspots within the 
sagebrush-steppe ecosystem. The specialized slickspot habitats were 
formed during the Pleistocene period and are considered a finite 
resource; the fact that these slickspots likely cannot be recreated or 
restored once they have been lost was an important consideration in our 
evaluation of the threats to L. papilliferum. In addition, the species' 
limited geographical range makes it particularly vulnerable to the many 
threats affecting its habitat. We have evidence indicating that the 
finite slickspot habitats of the species are continuing to degrade in 
quality from a variety of threats. Based on the best scientific data 
currently available, the primary significant threats to the species are 
the effects of wildfire and invasive nonnative plants, especially 
Bromus tectorum.
    In our 2007 finding (72 FR 1622; January 12, 2007), we concluded: 
``The best available data for Lepidium papilliferum indicate that while 
the broad scale habitat in which the species exists is degraded, we 
have no data that correlates this with species abundance.'' We now have 
new information indicating a statistically significant negative 
association between L. papilliferum abundance and wildfire, and between 
L. papilliferum abundance and cover of B. tectorum in the surrounding 
plant community; these negative associations are consistent throughout 
the range of the species. Wildfire occurs throughout the range of L. 
papilliferum and has dramatically increased in both frequency and 
extent over historical levels, especially where B. tectorum is 
dominant. We expect this trend to continue and possibly increase due to 
the projected effects of climate change. Furthermore, as B. tectorum 
and other nonnative annual grasses continue to spread and degrade the 
sagebrush-steppe ecosystem, we expect continued increases in fire 
frequency and magnitude, with associated negative impacts on L. 
papilliferum.
    As wildfire continues to promote the conversion of sagebrush to 
nonnative annual grasslands, we also anticipate that Owyhee harvester 
ants will expand into areas occupied by L. papilliferum, as the density 
of harvester ants is negatively associated with sagebrush cover, and 
they appear to readily colonize grassland habitats that are replacing 
sagebrush. Seed predation on L. papilliferum is thus expected to 
increase, with negative consequences for plant reproduction and the 
maintenance of the persistent seed bank.
    Additionally, future development threatens many of the remaining L. 
papilliferum occupied sites, primarily in the Snake River Plain and 
Boise Foothills. Development can result in the permanent loss of 
slickspot microsite habitats, and contributes to the problems 
associated with habitat fragmentation and the isolation of small 
populations. The loss of slickspots, particularly those slickspots 
occupied by the species and thus clearly providing the requisite 
conditions to support L. papilliferum, is of great concern due to the 
finite nature of this resource. Habitat fragmentation and isolation 
potentially reduces the long-term viability of populations by impeding 
genetic exchange through insect pollination or pollen dispersal, 
resulting in decreased seed production and possibly reduced genetic 
diversity.
    As with the 2007 finding (72 FR 1622; January 12, 2007), we do not 
see strong evidence of a steep negative population trend for the 
species. However, recent analysis of the best available scientific data 
suggests that Lepidium papilliferum numbers may be trending downward, 
and the dataset from the rough census areas on the OTA, which we 
consider to be the most reliable, shows a statistically significant 
downward trend in density over the last 18 years. The evidence suggests 
this negative trend is independent of any trend in precipitation over 
the same period of time. The extreme variability in annual abundance 
makes the detection of any such trend statistically challenging; not 
all monitoring data have shown consistently significant results, and, 
as described earlier, there are numerous factors that serve to 
complicate the confident detection of a population trend in this 
species. We do now have evidence, however, that the primary threats of 
wildfire and invasive

[[Page 52052]]

nonnative plants, especially B. tectorum, are currently acting on the 
species and its habitat throughout its limited range, and furthermore 
we now have evidence of a significant negative association between the 
abundance of L. papilliferum and these two threats. Indications are 
that all of the significant threats to L. papilliferum identified in 
this rule, including development and habitat fragmentation, but 
especially wildfire and invasive nonnative plants, will continue and 
likely increase into the foreseeable future. The projected future 
consequences of climate change, if realized, will further magnify the 
primary threats posed by wildfire and B. tectorum. Furthermore, we 
conclude from our evaluation of the ongoing and planned conservation 
efforts for Lepidium papilliferum that, despite the best efforts of the 
State and other management agencies, there is no information leading us 
to believe that sufficient management tools are currently being 
implemented that are capable of effectively reducing or ameliorating 
the primary threats of wildfire and invasive nonnative plants, 
particularly B. tectorum, across the range of L. papilliferum, to a 
point where the species is not likely to become endangered in the 
foreseeable future. As we can reasonably anticipate the continuation or 
increase of all of the significant threats to L. papilliferum into the 
foreseeable future, even after accounting for ongoing and planned 
conservation efforts, and based on the observed significant negative 
correlation between the primary threats of wildfire and invasive 
nonnative plants, particularly B. tectorum, and the abundance of L. 
papilliferum, we can reasonably infer that the negative consequences of 
these threats on the species will continue, and, under current 
conditions, population declines will likely be observed within the 
foreseeable future to the point at which L. papilliferum will become an 
endangered species.
    Section 3 of the Act defines an endangered species as ``any species 
which is in danger of extinction throughout all or a significant 
portion of its range'' and a threatened species as ``any species which 
is likely to become an endangered species within the foreseeable future 
throughout all or a significant portion of its range.'' Lepidium 
papilliferum is currently affected by a variety of threats across its 
entire geographic range. As we have not yet observed the extirpation of 
local populations or steep declines in the abundance of the species, we 
do not believe the status of the species is such that it is presently 
in danger of extinction. Therefore, we do not believe L. papilliferum 
meets the definition of an endangered species. We additionally 
considered whether any significant portion of the species' range meets 
the definition of endangered (see Significant Portion of the Range 
Evaluation, below); however, we could not determine that any 
significant portion of the species' range is presently in danger of 
extinction, thus no significant portion of the species range warrants 
listing as endangered. We can, however, reasonably anticipate the 
impacts of the threats on L. papilliferum rangewide, and we believe 
those threats acting in combination are likely to result in the species 
becoming endangered within the foreseeable future. Therefore, we are 
listing L. papilliferum as a threatened species throughout all of its 
range under the Act.

Significant Portion of the Range (SPR) Evaluation

    Section 3 of the Act defines an endangered species as a species in 
danger of extinction throughout all or a significant portion of its 
range, and a threatened species as a species that is likely to become 
an endangered species within the foreseeable future throughout all or a 
significant portion of its range.
    In our analysis for this final rule, we initially evaluated the 
status of and threats to the species throughout its entire range. 
Lepidium papilliferum is restricted to a relatively small range in 
southwestern Idaho. The range of the species has been divided into 
three physiographic regions, based on differences in topography, soil, 
and relative abundance of L. papilliferum. These three physiographic 
regions, shown in Figure 1, are the Boise Foothills, Snake River Plain, 
and Owyhee Plateau. In our evaluation of threats to L. papilliferum, we 
determined that the threats acting on the species may differ in 
severity to some degree between these physiographic regions, as 
demonstrated by Sullivan and Nations (2009, Chapter 8, pp. 97-138). On 
the basis of this evaluation, we determined that the entire species 
meets the definition of threatened under the Act due to the loss or 
degradation of its habitat, due primarily to the modified wildfire 
regime and invasive nonnative plant species. The basis of this 
determination is captured within the analysis of each of the five 
listing factors, and the Finding immediately preceding this section.
    Recognizing the potential differences in the magnitude of threats, 
we evaluated whether there were any specific areas or populations that 
may be disproportionately threatened such that they currently meet the 
definition of an endangered species versus a threatened species. Our 
evaluation of whether there are any significant portions of Lepidium 
papilliferum's range (SPR) where listing the species as endangered may 
be warranted follows.
    On March 16, 2007, a formal opinion was issued by the Solicitor of 
the Department of the Interior, ``The Meaning of `In Danger of 
Extinction Throughout All or a Significant Portion of Its Range''' 
(USDI 2007). We have summarized our interpretation of that opinion and 
the underlying statutory language below.
    In determining whether a species is threatened or endangered in a 
significant portion of its range, we first identify any portions of the 
range of the species that warrant further consideration. The range of a 
species can theoretically be divided into portions in an infinite 
number of ways. However, there is no purpose to analyzing portions of 
the range that are not reasonably likely to be significant and 
threatened or endangered. To identify those portions that warrant 
further consideration, we determine whether there is substantial 
information indicating that (i) the portions may be significant and 
(ii) the species may be in danger of extinction there or likely to 
become so within the foreseeable future. In practice, a key part of 
this analysis is whether the threats are geographically concentrated in 
some way. If the threats to the species are essentially uniform 
throughout its range, no portion is likely to warrant further 
consideration. Moreover, if any concentration of threats applies only 
to portions of the range that are unimportant to the conservation of 
the species, such portions will not warrant further consideration.
    If we identify any portions that warrant further consideration, we 
then determine whether in fact the species is threatened or endangered 
in any significant portion of its range. Depending on the biology of 
the species, its range, and the threats it faces, it may be more 
efficient for the Service to address the significance question first, 
or the status question first. Thus, if the Service determines that a 
portion of the range is not significant, the Service need not determine 
whether the species is threatened or endangered there. Alternatively, 
if the Service determines that the species is not threatened or 
endangered in a portion of its range, the Service need not determine if 
that portion is significant. If the Service determines that both a 
portion of the range of a species is significant and the

[[Page 52053]]

species is threatened or endangered there, the Service will specify 
that portion of the range as threatened or endangered pursuant to 
section 4(c)(1) of the Act.
    To determine whether any portions of the range of Lepidium 
papilliferum warrant further consideration as possible endangered 
significant portions of the range, we reviewed the entire supporting 
record for this final listing determination with respect to the 
geographic concentration of threats and the significance of portions of 
the range to the conservation of the species. In this case, we first 
evaluated whether substantial information indicated (i) the threats are 
so concentrated in any portion of the species' range that the species 
may be currently in danger of extinction in that portion; and (ii) if 
so, whether those portions may be significant to the conservation of 
the species.
    Our rangewide review of the species concluded that Lepidium 
papilliferum is likely to become endangered within the foreseeable 
future. Therefore, the species meets the definition of threatened under 
the Act. As described above, to establish whether any areas may warrant 
further consideration, we reviewed our analysis of the five listing 
factors to determine whether any of the significant threats identified 
were so concentrated that some portion of L. papilliferum's range may 
currently be in danger of extinction. All of the significant threats 
identified in this rule, the primary threats of modified wildfire 
regime and invasive nonnative plant species, and the lesser threats of 
development and habitat fragmentation and isolation, act on the species 
throughout its range. The threat of development is somewhat greater in 
the Boise Foothills and Snake River Plain physiographic regions 
relative to the Owyhee Plateau, but as discussed in our analysis under 
Factor A, we have no information indicating that this threat is so 
imminent or disproportionately severe as to place the species in danger 
of extinction within those physiographic regions at present. In 
addition, the analysis of Sullivan and Nations (2009) demonstrated that 
the magnitude of the threats to L. papilliferum from some factors, such 
as individual species of invasive nonnative plants (e.g., Agropyron 
cristatum) may vary to some degree between physiographic regions. 
However, based on our review of the record, we did not find substantial 
information indicating that any of the significant threats to the 
species were so severe or so concentrated as to indicate that some 
portions of L. papilliferum's range qualify as endangered. As described 
in our Finding above, the threats are such that we anticipate L. 
papilliferum will become endangered within the foreseeable future 
across its range. However, at present we have no evidence of any recent 
localized population extirpations, nor is there evidence of any 
localized precipitous population declines indicating that L. 
papilliferum is currently in danger of extinction in any portion of its 
range. As a result, while the best scientific data available allows us 
to make a determination as to the rangewide status of L. papilliferum, 
we have determined that the best available data show that there are no 
portions of the range in which the threats are so concentrated as to 
place the species currently in danger of extinction. Because we find 
that L. papilliferum is not endangered in any portion of its range, we 
need not address the question of whether any portion may be 
significant.

Peer review

    In accordance with our peer review policy published on July 1, 1994 
(59 FR 4270), and current Department of the Interior guidance, we 
solicited seven individuals with scientific expertise on Lepidium 
papilliferum, its habitat, and the geographic region in which the 
species occurs to provide their expert opinion and to review and 
interpret available information on the species' status and threats. 
Four of the seven peer reviewers had previously participated on a May 
2006 expert panel of independent scientists convened to evaluate the 
available data and threats to L. papilliferum as part of our 2007 
listing determination. Although all seven of the original expert 
panelists were invited to participate in the current evaluation, not 
all were available to do so. The peer reviewers were asked for their 
expert opinion on the best available information by responding to a 
series of questions posed by the Service regarding L. papilliferum 
population trends, threat factors, and their effects on L. papilliferum 
population viability. We received responses and comments from six of 
the seven peer reviewers, which are provided in the following summary 
and incorporated into the final rule as appropriate.
Peer Review Comments and Responses

Population Trend

    (1) Comment: The peer reviewers differed in their explanation for 
describing a population trend for Lepidium papilliferum. One peer 
reviewer stated they have ``no confidence in any trend data due to 
small sample size and lack of independence between years,'' and 
asserted that there are no data to indicate that the population is in 
decline. Two peer reviewers agreed that the available information 
revealed a significant declining trend that was not strong for the 
years analyzed, but expressed a lack of confidence that this trend 
could be reliably projected into the future. Another peer reviewer did 
not see strong evidence for a declining population and believed that 
viable populations would be maintained over the next 50 years if 
current conservation efforts continue. One peer reviewer offered that 
``ultimately, the availability and quality of suitable habitat, not 
past population trends, will determine L. papilliferum's population 
trajectory.''
    Our Response: In our 2007 withdrawal of the proposed rule to list 
Lepidium papilliferum as endangered (72 FR 1622; January 12, 2007), we 
stated that data on overall population trends for L. papilliferum were 
inconsistent. Since that time we have received and evaluated new 
information, including independent statistical analyses of long-term 
plant monitoring data, in an attempt to discern any long-term trend in 
the abundance of the species. We acknowledge that forming a reliable 
estimate of trend in the abundance of L. papilliferum over time is 
complicated by multiple factors; however, we are mandated by the Act to 
use the best available scientific and commercial data in our 
assessment. Therefore, we have relied upon that data we have determined 
to be most reliable for the discernment of population trend. As 
described above in the section Population Abundance and Trend, one 
complicating factor is that individual plants may act as either an 
annual or a biennial form in any given year, and there can be varying 
numbers of plants acting as either spring-flowering annuals or 
overwintering rosettes. The relative proportions of these two life-
history forms can fluctuate annually depending on a variety of factors, 
including precipitation, temperature, and the abundance of rosettes 
produced the previous year (Unnasch 2008, pp. 14-15; Sullivan and 
Nations 2009, pp. 43-44, 134-135). Another factor is that L. 
papilliferum has a seed bank with a longevity of approximately 12 
years, likely as an adaptation to a highly variable environment. Years 
of good rainfall favorable for germination and survival may be followed 
by periods of drought; a persistent seed bank provides a population 
buffer against years of poor

[[Page 52054]]

reproductive performance in a highly variable environment (Meyer et al. 
2005, p. 21). The tendency of only a small percentage of a single 
year's seed cohort to germinate in any given year over a 12-year period 
results in a significant lag effect in detecting any real underlying 
change in total population abundance over the long term.
    Further complications are posed by the extreme annual variability 
observed in plant numbers. This challenge was recognized by Mancuso and 
Moseley (1998, p. 1), who noted the difficulty in discerning any real 
trend in population abundance of above-ground individuals of Lepidium 
papilliferum, since in many years the majority of the population is 
represented by the seed bank, hence sites that ``have thousands of 
individuals one year may have none the next year.'' Some of the 
variability in yearly plant numbers is likely due to the relationship 
between L. papilliferum and precipitation. The annual abundance or 
density of L. papilliferum plants shows a significant positive 
association with the levels of spring rainfall, roughly from March 
through May (Meyer et al. 2005, p. 15; Palazzo et al. 2005, p. 9; 
Sullivan and Nations 2009, pp. 39-41), and the survival of biennials is 
associated with increased summer rainfall (Meyer et al. 2005, p. 15). 
In addition, temperature appears to play a role in annual abundance of 
L. papilliferum in concert with precipitation, although the exact 
nature of that relationship is complex and not well understood 
(Sullivan and Nations 2009, p. 57).
    We contracted with independent consultants to analyze the available 
population data for Lepidium papilliferum, to assist us in determining 
which datasets represent the best available information and to provide 
an independent assessment of any population trend in the species, if 
possible. The resulting report, cited in this document as Sullivan and 
Nations 2009, was prepared to evaluate monitoring and survey 
methodologies and conduct statistical analyses on Lepidium papilliferum 
data collected on the OTA since 1990, as well as to analyze the 
rangewide Habitat Integrity and Population (HIP) monitoring data 
collected over the past 5 years (see our response to the State of Idaho 
Comments, below, for more information on the Sullivan and Nations 2009 
report). This report was made available to the peer reviewers. The 
evaluation of Sullivan and Nations was based on a simple model of L. 
papilliferum abundance or density as a linear function of time, 
intended only to discern whether there was any general trend in the 
population; the authors acknowledge that the dynamics are complicated, 
and note that their model is not intended to describe (nor explain) the 
details of the temporal pattern of abundance or density of L. 
papilliferum (Sullivan and Nations 2009, p. 38). The authors concluded 
that the population data from the rough census monitoring on the OTA 
represents the most reliable dataset for the species, and that there is 
``limited evidence for declining populations,'' in that trends on the 
OTA are negative but only statistically significant for the rough 
census areas (Sullivan and Nations 2009, pp. 2, 44).
    The extreme variability in annual counts of the species makes it 
difficult to discern a trend in numbers with statistical confidence; 
for this reason for the purposes of modeling a trend through time, we 
place greater confidence in the longest time series of monitoring data 
available, which is from the OTA (up to 18 years of data for some rough 
census areas and all special-use plots). This is in agreement with the 
independent assessment of Sullivan and Nations (2009, pp. 3, 36, 93). 
In addition, those authors had slightly greater confidence in the data 
from the rough census areas on the OTA, since they are larger than the 
special-use plots and have multiple slickspots; therefore, the counts 
are less susceptible to localized impacts (Sullivan and Nations 2009, 
p. 55).
    Because the OTA data on Lepidium papilliferum abundance and density 
results from a standardized collection effort over a period of nearly 
20 years, we consider the information from the OTA to be the best 
available data with which to detect any general long-term population 
trend for L. papilliferum. The analysis of this dataset from the rough 
census areas on the OTA shows a statistically significant downward 
trend in density of L. papilliferum over the last 18 years. This trend 
appears to be independent of any trend in precipitation over the same 
time period, indicating this decline is occurring due to factors other 
than precipitation pattern (Zwartjes 2009, p. 1). We therefore conclude 
that the best available data suggest that Lepidium papilliferum numbers 
are probably trending downward. Furthermore, since this significant 
downward trend has been detected on the OTA, which represents some of 
the highest quality habitat remaining for L. papilliferum, we believe 
it is reasonable to infer that this negative trend is similar or 
possibly even greater rangewide, in areas of lower quality habitat.
    We note that one peer reviewer questioned whether a decline in 
Lepidium papilliferum abundance is really occurring, based on high 
numbers of plants recorded in 2008. Another peer reviewer, however, had 
little confidence that this one-time observation was indicative of any 
long-term increasing trend. We note that the increase in numbers of L. 
papilliferum in 2008 is largely based on substantial increases at only 
6 out of 80 HIP transects; 66 percent of all L. papilliferum counted in 
2008 were found at these 6 transects (Colket 2009, p. 26). Furthermore, 
the plant community where these six transects are located has not been 
burned, and is dominated by native sagebrush (Artemisia tridentata). 
These six transects therefore represent some of the highest-quality 
habitat remaining for L. papilliferum. Since the increases observed in 
2008 were highly localized and occurred in remnant high-quality 
habitats, and considering that rangewide most L. papilliferum 
occurrences are in degraded habitats and counts tend to be highly 
variable from year to year, we do not believe it is reasonable to infer 
that this one-time increase in abundance portends any future rangewide 
increases in abundance of the species. Please also see ``2008 HIP 
Survey Results'' under our response to public comments number 12, 
below.

Data Quality

    (2) Comment: One peer reviewer stated that information contained in 
many of the study reports is based on data that were not collected for 
specific analysis, but instead represents an analysis that was 
performed on data whose accuracy is unknown or from small data sets 
comprised of interdependent data. Another peer reviewer noted the 
difficulty in comparing different data sets as well as data sets with 
differing collection methodologies; while another reviewer identified 
that several of the data sets examined were collected over such short 
periods (2 to 3 years) that the study results were of limited value. In 
contrast, another peer reviewer stated that it is important to make 
conclusions based on available information when unequivocal data is 
lacking.
    Our Response: The Act requires us to make listing decisions based 
solely on the best scientific and commercial information available at 
the time the decision is being made (section 4(b)(1)(A)). We thoroughly 
reviewed and evaluated all available scientific and commercial data for 
Lepidium papilliferum in preparing this final listing determination. We 
reviewed historical and recent publications, as well as unpublished 
reports concerning L. papilliferum and sagebrush-steppe

[[Page 52055]]

habitats of southwestern Idaho. As part of our process, the seven peer 
reviewers were asked to provide a critical examination of the new 
scientific information pertaining to L. papilliferum. This information 
included both long-term and recent HII/HIP rangewide survey and 
monitoring data, the statistical analyses of long-term OTA monitoring 
data, and the 5 years of available HIP monitoring data completed by an 
independent consultant. In addition, we received an independent 
critique of the methodologies of several recent reports or analyses of 
L. papilliferum data (Sullivan and Nations 2009, pp. 139-148), to 
assist in our assessment of the best available data.
    We agree that the differing methodologies and lack of 
standardization present challenges in evaluating the data relevant to 
Lepidium papilliferum. Furthermore, much of the data are observational 
in nature; that is, the data were not collected based on controlled 
experiments, but are primarily based on observations of the relative 
conditions or abundance of various environmental variables, such as 
livestock print cover and the relative abundance of L. papilliferum. 
However, as noted above, we have a legal obligation under the Act to 
make a determination based upon the best scientific and commercial data 
available at the time; the statute does not provide for additional 
research, nor does it provide the option of not making a determination. 
We must therefore evaluate all of the scientific and commercial data 
before us to determine which data we consider to be the best available. 
As part of our evaluation, we carefully considered factors such as the 
time series of data collection, the variability of the data, and 
standardization of data-collection procedures in weighing the relative 
value or reliability of study results. We considered all of these 
factors in considering the relative quality of the data available, and 
in determining which data to rely upon in our determination. Throughout 
our review and evaluation, we followed the Service's Information 
Quality Guidelines (USFWS 2007) to prepare this final determination.

Threats to the Species

    (3) Comment: The peer reviewers varied in describing which threats 
they considered to be of primary importance to the population viability 
of Lepidium papilliferum. Three of the six peer reviewers expressed 
concern regarding the impact of wildfire on L. papilliferum and its 
habitat, while four of six peer reviewers mentioned habitat degradation 
and loss of the sagebrush-steppe habitat from exotic and invasive 
nonnative grasses to be of concern or a primary threat. Other threats 
identified included development (two reviewers), seed predation by 
harvester ants (two reviewers), and habitat fragmentation (two 
reviewers). One reviewer identified livestock as a potential threat, 
one reviewer asserted that there are no good data to suggest that 
livestock are a threat, and one reviewer suggested that, if managed 
appropriately, livestock could be utilized to manage the threat of 
nonnative invasive grasses and the associated increase in fire 
frequency. One peer reviewer stated that there are few reliable 
scientific studies to show any cause-and-effect relationships to L. 
papilliferum, and stated that the species continues to exist in areas 
of supposed threats, including ``burned over areas.''
    Our Response: In making this determination, we evaluated several 
potential threat factors including the effects of wildfire; invasive 
nonnative plants; development; seed predation; livestock use; wildfire 
management; habitat fragmentation and small populations; military 
training; recreation; and climate change. Of all the threat factors 
examined, we determined that the modified wildfire regime affecting the 
species' sagebrush-steppe habitat in combination with the spread of 
nonnative invasive annual plants such as Bromus tectorum and 
Taeniatherum caput-medusae are likely the primary factors affecting 
abundance and the long-term persistence of Lepidium papilliferum. 
Tightly controlled experiments that demonstrate clear causal 
relationships between variables examined are rare. Studies that 
demonstrate a significant or non-significant correlation between 
variables are prevalent in the scientific literature, and in many 
cases, depending on factors such as the quality of the data and 
analysis, constitute the best information available. For example, such 
analyses have demonstrated a significant negative relationship between 
the density or abundance of L. papilliferum and the occurrence of fire 
and cover of B. tectorum (Sullivan and Nations 2009, pp. 116-118, 130-
131, 135-137). Based on this observed significant relationship, we 
infer that as the occurrence of fire and the cover of B. tectorum 
increase, we will observe a decrease in the density or abundance of L. 
papilliferum. A complete review and evaluation of the threats affecting 
L. papilliferum, including a discussion of our rationale in assessing 
those threats, is presented in the Summary of Factors Affecting the 
Species section of this rule.
    (4) Comment: The peer reviewers varied in their estimates of a time 
period over which they could reliably predict the effects of threats, 
both individually and synergistically, on the population viability and 
survival of Lepidium papilliferum. One peer reviewer could not 
``reliably predict the effect of each of the primary threats to the 
species, based on the data before me since the data does not exist.'' 
Another peer reviewer suggested that given current trends in habitat 
loss and degradation, Lepidium papilliferum ``is likely at a tipping 
point in terms of its prospect for survival,'' and doubted that the 
species would persist in sustainable numbers beyond the next 50 to 75 
years. Most peer reviewers did not project a time period for predicting 
threat effects or extinction risk, stating that future projections were 
likely speculative.
    Our Response: As described above, the Act requires us to make 
listing decisions based solely on the best scientific and commercial 
data available at the time the decision is being made (section 
4(b)(1)(A)). Based upon the best scientific and commercial data 
available, we must make a determination as to whether the species under 
consideration is in danger of extinction throughout all or a 
significant portion of its range (endangered), or if the species is 
likely to become endangered within the foreseeable future throughout 
all or a significant portion of its range (threatened). We consider the 
``foreseeable future'' to be that period of time over which events can 
reasonably be anticipated. In considering threats to the species and 
whether they rise to the level such that listing the species as 
threatened or endangered is warranted, we assess factors such as the 
imminence of the threat (is it currently impacting the species, and is 
it reasonable to expect the threat to continue into the future?), the 
scope or extent of the threat, the severity of the threat, and the 
synergistic effects of all threats combined. If we determine that the 
species is not currently in danger of extinction, then we must 
determine whether, based upon the nature of the threats, it is 
reasonable to anticipate that the species may become in danger of 
extinction within the foreseeable future.
    We have identified the present or threatened destruction, 
modification, or curtailment of Lepidium papilliferum's habitat or 
range as a threat to the species, based on the observed negative 
association between the abundance or density of the plant and the 
current, frequent fire regime and invasion of

[[Page 52056]]

Bromus tectorum and other nonnative plants, as well as the direct loss 
of limited slickspot microsite habitats to development. Predation is an 
additional threat to the persistence of the species, as seed predation 
by harvester ants has potentially significant consequences for the 
plant's seed bank, and the presence of harvester ants appears to be 
associated with the observed conversion of sagebrush-steppe to 
nonnative annual grasslands. Habitat fragmentation and isolation 
resulting from development and associated infrastructure, such as 
utility lines, contributes to the threats of wildfire and nonnative 
plant invasion, and may additionally impact L. papilliferum by limiting 
genetic exchange between populations via insect pollination. Climate 
change may further accelerate the conversion of intact sagebrush-steppe 
habitat to invasive nonnative annual grasslands, with subsequent 
associated increases in wildfire frequency and, potentially, harvester 
ant expansion. These threats are all occurring at present, and based on 
the evidence before us, we believe it is reasonable to anticipate that 
the current regime of frequently recurring wildfires, the invasion of 
nonnative grasses and other plants, development, and the expansion of 
harvester ants will continue and likely increase into the foreseeable 
future. Although conservation measures to address some of these threats 
have been considered and in some cases implemented, effective controls 
throughout the range of the L. papilliferum are simply not available in 
many cases. For example, it is not anticipated that landscapes 
dominated by B. tectorum can feasibly be restored to intact sagebrush-
steppe habitat within the foreseeable future, as restoration of L. 
papilliferum's native sagebrush-steppe ecosystem is considered one of 
the greatest restoration challenges in the Great Basin (Bunting et al. 
2003, pp. 82-84). Moreover, the threats to L. papilliferum can 
reasonably be anticipated to continue or increase. This information, in 
concert with the observed negative association between these threats 
and the abundance of the species (in the further context of 
considerations such as the limited geographic extent of the species' 
range and the finite nature of its slickspot microhabitats), lead us to 
the conclusion that it is reasonable to anticipate that L. papilliferum 
is likely to become endangered in the foreseeable future. Based on our 
assessment of the best scientific and commercial data available 
regarding the past, present, and future threats faced by the species, 
we have therefore determined that L. papilliferum is a threatened 
species, as defined by the Act.

Seed Dispersal

    (5) Comment: One peer reviewer suggested that the seeds of L. 
papilliferum can be widely dispersed by high winds, in addition to 
potential dispersal by animals. This reviewer stated that the seeds 
produce mucilage when wet and may likely have been dispersed by 
clinging to the wool of sheep, citing Rollins 1993, and suggests that 
L. papilliferum is not necessarily so highly specialized in its habitat 
requirements, but that the current distribution of L. papilliferum may 
be due to the past activities of Basque sheep herders.
    Our Response: We acknowledge that the seeds of Lepidium 
papilliferum may occasionally be dispersed by wind. However, the 
species does not demonstrate any of the usual adaptations to assist in 
wind dispersal, such as winged seeds, that would indicate wind as the 
usual mode of dispersal for the species. In the paper cited by the 
reviewer, Rollins (1993, p. 535) suggests that the seeds of plants in 
the genus Lepidium may potentially be dispersed by sheep; this study 
was not specific to L. papilliferum, but appears to be more relevant to 
weedy Lepidium species of Europe and Asia, such as L. perfoliatum. In 
evaluating whether the present range of L. papilliferum may be due to 
the activities of either wind or Basque sheepherders, we considered 
both the current knowledge of the range of L. papilliferum and the 
results of recent genetic studies. Lepidium papilliferum is endemic to 
southwest Idaho, and the best available information indicates that 
there are no populations reported in other States where the Basques 
from Idaho would have also ranged with their sheep, thus indicating 
that sheep were likely not the primary vectors for seed dispersal that 
resulted in the current range of the species. In addition, if wind 
dispersal defined the range of the species, we would not expect the 
species to be confined to this limited range in southwest Idaho, as the 
wind would certainly be capable of carrying seeds beyond the present 
boundaries within which L. papilliferum is found. Finally, genetic 
studies showing that smaller populations of L. papilliferum have 
reduced genetic variability (Larson et al. 2006, p. 17) is not 
consistent with the theory that the seeds are wind-dispersed, which 
would provide a consistent source of genetic mixing and reduce the 
genetic isolation of these small populations, thereby maintaining 
genetic diversity. We therefore conclude that seed dispersal by wind or 
sheep is most likely not responsible for the current distribution of L. 
papilliferum, nor are these processes currently occurring at a level 
that is significant to the life history of the species.

Summary of Public Comments and Recommendations

    Since the proposed rule was reinstated by the Court, there have 
been two public comment periods. During the September 19, 2008, 30-day 
comment period for the proposed rule, we received a total of seven 
comment letters in response to our request for new information: two 
from Federal agencies and five from organizations or individuals. The 
State of Idaho submitted comments and new information after the close 
of the comment period. During the March 17, 2009, 30-day comment 
period, we received 14 comments, including 6 solicited from peer 
reviewers. Of the public comments, all were received either in written 
form or through the portal at: http://www.regulations.gov.
    Two public commenters generally supported the proposed rule to list 
the species; seven were opposed to the proposed rule, and the remaining 
were either neutral or provided new information regarding the proposed 
rule. Comments that provided new information were incorporated into 
this final determination, or are addressed below. Public comments 
received were grouped into six general issues, and are addressed in the 
following summary.
Public Comments

New Information

    (6) Comment: Several commenters provided new data and information 
regarding the biology, ecology, life history, and threat factors 
affecting Lepidium papilliferum, and requested it be incorporated into 
the body of existing information the Service has on the species and be 
considered by us in making any future listing determinations.
    Our Response: We thank the commenters who provided new data and 
information for our consideration in making this final listing 
determination. We have considered scientific and commercial information 
regarding Lepidium papilliferum contained in over 100 technical 
documents, published journal articles, and other general literature 
documents, including over 50 documents we have received since the 
January 2007 withdrawal of the proposed rule to list L. papilliferum 
(72 FR 1622; January 12, 2007). The body of available information 
specific to

[[Page 52057]]

L. papilliferum has increased since 2007, including new scientific 
information regarding the species' biology, ecology, and distribution; 
habitat quality monitoring; the implementation and effectiveness of 
ongoing conservation efforts; and information pertaining to threat 
factors affecting the species. This information was contained in State 
Agency reports (ICDC 2007a; ICDC 2007b; Quinney 2007; ICDC 2008; IDFG 
2008; State of Idaho 2008; Unnasch 2008; Colket 2009; Robertson and 
White 2009) and other scientific reports and peer-reviewed articles 
(Billinge and Robertson 2008; Palazzo et al. 2008; Smith et al. in 
press). We also considered information contained in population survey 
and monitoring reports (Boise Airport 2003; Hoffman 2005; ICDC 2007b; 
Quinney 2007; U.S. Air Force (CH2MHill 2007a,b, 2008a,b); U.S. BLM 
2007, 2008a; Cole 2008; Colket 2009). Additionally, to gain a better 
understanding of existing monitoring data, we contracted with 
independent consultants to conduct several analyses, including: a 
statistical analysis on long-term monitoring data collected at the OTA, 
an analysis of rangewide HIP data, and an assessment of the 
methodologies of other recent analyses (Sullivan and Nations 2009); a 
statistical and geospatial analysis of data collected during 2000-2002 
field surveys at the Inside Desert of the Owyhee Plateau (Popovich 
2009); and a geospatial analysis of wildfire and vegetation types 
within the range of L. papilliferum (Stoner 2009). Finally, in order to 
assess any potential relationship between abundance or density of L. 
papilliferum and precipitation trends over time, we conducted our own 
analysis of precipitation patterns at the OTA (Zwartjes 2009). All of 
the documents were made available to the public and provided to the six 
peer reviewers.

Appropriate Listing Status of Lepidium papilliferum

    (7) Comment: One commenter stated that the Service should 
immediately move to list Lepidium papilliferum as endangered and 
simultaneously designate critical habitat. Conversely, the State of 
Idaho ``remains steadfast in its belief that the species does not 
warrant this protection'' (see State of Idaho comments, below). One 
other commenter agreed with this position and two commenters indicated 
that there is inadequate scientific information to make a decision to 
list L. papilliferum at this time, and requested additional studies be 
completed.
    Our Response: Section 4(b)(1)(A) of the Act requires us to make 
listing decisions based solely on the best scientific and commercial 
data available. The Service has a legal obligation to make a 
determination based on the best available data before us at the time 
the decision is being made; the statute does not provide for additional 
research, nor does it provide the option of not making a determination. 
We have thoroughly reviewed all available scientific and commercial 
data for Lepidium papilliferum in preparing this final listing 
determination. We reviewed historical and recent publications as well 
as unpublished reports concerning L. papilliferum and the sagebrush-
steppe habitat where it occurs in southwestern Idaho. In addition, we 
utilized peer review to provide a more focused, independent examination 
of the available scientific information and its application to the 
current status of the species. Finally, we contracted with independent 
consultants to assist us in analyzing L. papilliferum abundance and 
habitat quality monitoring data. As described in our response to peer 
review comments above (number 2), as part of our evaluation, we 
carefully consider the quality and reliability of all data to decide 
which constitutes the best available data for our consideration in 
making our final determination.
    Our evaluation of the significance of the threat factors across the 
range of Lepidium papilliferum is presented in the Summary of Factors 
Affecting the Species section of this final determination. Additional 
discussion of our application of the standards of the Act in making our 
determination is provided in our response to peer review comment number 
4, above. Lepidium papilliferum is currently affected by threat factors 
across its entire geographic range. Based on our evaluation, we believe 
it is reasonable to anticipate that the negative impacts of these 
threats on L. papilliferum rangewide will continue and even increase. 
Although we consider the impacts of these threats to be foreseeable and 
likely to result in the species becoming endangered within the 
foreseeable future, we do not consider L. papilliferum to be currently 
in danger of extinction. Furthermore, while we acknowledge the efforts 
of the State and other entities to implement conservation measures for 
the species, the best available information leads us to believe that 
currently available management tools are not capable of effectively 
reducing or ameliorating these threats across the range of the species. 
Based on our assessment of the best scientific and commercial data 
available regarding the threats faced by the species, we have 
determined that L. papilliferum meets the definition of a threatened 
species under the Act. We have also determined that designating 
critical habitat for L. papilliferum is prudent but not determinable at 
this time (see Critical Habitat Determinability, below).

Taxonomic Status of Lepidium papilliferum

    (8) Comment: One commenter suggested that Lepidium papilliferum is 
a local variation of Lepidium montanum, and therefore is not a species 
or subspecies as defined under the Act. Another commenter stated that 
considerable uncertainty remains regarding the taxonomy of L. 
papilliferum and suggested that the Service conduct a genetic study to 
resolve any taxonomic disputes.
    Our Response: Lepidium papilliferum was originally described as L. 
montanum var. papilliferum in 1900 by Louis Henderson. It was renamed 
L. papilliferum by Aven Nelson and J. Francis Macbride in 1913 based on 
its distinctive growth habit, short lifespan, and unusual pubescence 
(Nelson and Macbride 1913, p. 474). Hitchcock regarded L. papilliferum 
as L. montanum var. papilliferum, influencing several publications, 
including Flora of Idaho and Flora of the Pacific Northwest (Hitchcock 
et al. 1964, p. 516; Hitchcock and Cronquist 1973, p. 170; Steele 1981, 
p. 55; Moseley 1994, p. 2). In a 1993 review of taxa in the mustard 
family (Brassicaceae), Rollins maintained the species as L. 
papilliferum based on differences in the physical features between the 
two species such as:
    (1) L. papilliferum has trichomes (hair-like structures) occurring 
on the filaments of stamens (the part of flower that produces pollen), 
but L. montanum does not;
    (2) All the leaves on L. papilliferum are pinnately divided whereas 
L. montanum has some leaves that are not divided;
    (3) The shape of the seed capsule (silicle [silique]) of L. 
papilliferum is different from that of L. montanum; and
    (4) The silicle of L. papilliferum has no wings, or even vestiges 
of wings, at its apex (end of the capsule), unlike that of L. montanum 
(Rollins 1993, p. 578; Moseley 1994, p. 2). A review of the taxonomic 
status by Lichvar (2002), using classic morphological features and 
study of herbarium specimens, concluded that L. papilliferum has 
distinct morphological features that warrant species recognition. In 
addition, Meyer et al. (2005, p. 17) describe a

[[Page 52058]]

contrast in life history when compared to L. montanum regarding seed 
dormancy and the seed bank. Lepidium papilliferum seeds can remain 
dormant (and viable) and persist in the seed bank for up to 12 years; 
in contrast, L. montanum has largely nondormant seeds (Meyer et al. 
2005, p. 17). Resolving one commenter's concern, a recent genetic study 
compared L. montanum, L. papilliferum, and L. fremontii. Results of the 
study indicated that L. fremontii and L. papilliferum are 
morphologically and ecologically distinct from L. montanum, with 
apparently little gene flow between L. fremontii and L. papilliferum, 
and L. montanum (Smith et al. in press, p. 18). Lepidium papilliferum 
is recognized as a distinct species by Intermountain Flora (Holmgren et 
al. 2005, p. 259), the U.S. Department of Agriculture's ``PLANTS 
Database'' (USDA 2006), and the Biota of North America Project (ITIS 
2009). After considering all of this information, we believe that L. 
papilliferum is properly recognized as a full species, separate from L. 
montanum.
    The Act requires the Service to use the best scientific data 
available when making listing determinations under section 4 of the 
Act. The Act, therefore, does not require the Service to conduct its 
own studies on species it is considering for protection under the Act, 
including genetic studies on the taxonomy of those species.

Conservation Agreements

    (9) Comment: One commenter stated that the 2003 Candidate 
Conservation Agreement for Slickspot Peppergrass (CCA) by the State of 
Idaho, BLM, and others ``falsely assured'' readers that it would 
protect Lepidium papilliferum and its habitat. We also received 
information from the State of Idaho and the BLM describing ongoing 
conservation actions they are implementing under the CCA.
    Our Response: We strongly support a collaborative conservation 
effort to address factors affecting species being considered for 
listing under the Act. Since February 2000, we have worked with 
numerous agencies and individuals to assess the status of Lepidium 
papilliferum and to identify and implement conservation actions on its 
behalf. We continue to participate as a technical advisor to an 
interagency group of biologists and stakeholders to share scientific 
information and coordinate conservation actions for L. papilliferum and 
its habitat.
    In 2006, as part of a previous status review for Lepidium 
papilliferum, we conducted an evaluation of individual conservation 
efforts contained in five different plans, or conservation strategies, 
developed for L. papilliferum. These five plans were: (1) the 2003 CCA; 
(2) the Idaho Army National Guard (IARNG) Integrated Natural Resource 
Management Plan (INRMP) for Gowen Field/Orchard Training Area; (3) the 
U.S. Air Force INRMP for Mountain Home Air Force Base; (4) the 
Conservation Agreement by and between the City of Boise and the Service 
for Allium aasea (Aase's onion), Astragalus mulfordiae (Mulford's 
milkvetch) and L. papilliferum, also known as the Hull's Gulch 
Agreement; and (5) the Conservation Agreement for slickspot peppergrass 
(Lepidium papilliferum) at the Boise Airport, Ada County, Idaho.
    The majority of the conservation efforts developed on behalf of 
Lepidium papilliferum that we examined are contained in the 2003 State 
of Idaho CCA, which was updated in 2006. The CCA includes efforts that 
are intended to address the need to maintain and enhance L. 
papilliferum habitat; reduce the intensity, frequency, and size of 
natural and human-caused wildfires; reduce the potential for invasion 
of nonnative plant species from wildfire; minimize the loss of the 
species' habitat associated with rehabilitation and restoration 
techniques; minimize the establishment of invasive nonnative species; 
mitigate the negative effects of military training and other associated 
activities; and minimize the impact of ground disturbances caused by 
livestock penetrating trampling during periods when soils are 
saturated. The IDARNG and U.S. Air Force are also implementing 
conservation efforts on lands they manage to potentially avoid or 
reduce adverse effects of military training on L. papilliferum and its 
habitat. For example, the IDARNG has been implementing conservation 
efforts at the OTA since 1991 that promote the conservation of L. 
papilliferum, while still providing for military training activities. 
These actions include intensive wildfire suppression efforts, and 
restricting ground operated military training to areas where the plants 
are not found. The U.S. Air Force INRMP was modified in 2004 and 
contains more measures that promote the conservation of L. papilliferum 
than the 2000 version. The current INRMP includes measures developed to 
minimize the effects of threats such as wildfire, nonnative invasive 
weeds, and livestock use on L. papilliferum. The Boise Airport 
Conservation Agreement lays out measures to protect and conserve the 
known occurrences of L. papilliferum at the airport, while the Hull's 
Gulch Conservation Agreement focuses on coordinating and planning 
activities with the Service in Hull's Gulch in the Boise Foothills.
    With the exception of conservation efforts implemented by the 
IDARNG over the past 18 years, many of the conservation efforts 
presented in the conservation plans, although laudable, have not been 
implemented over a period of time long enough for effectiveness to be 
adequately demonstrated. Similarly, the adaptive management provisions 
in the 2003 State of Idaho CCA have not been implemented long enough to 
have sufficient certainty of their effectiveness in addressing the 
long-term conservation of L. papilliferum. We recognize the 
conservation efforts identified in the conservation plans can have 
benefits for the species and its habitat, particularly with limiting 
the effects of wildfire and livestock use. Despite the best intentions, 
however, many of the measures identified in the conservation plans are 
limited in their ability to effectively reduce long-term habitat 
degradation or loss in the sagebrush-steppe ecosystem, including the 
negative impacts observed on slickspots and L. papilliferum associated 
with that degradation or loss. For example, there is currently no 
effective control of Bromus tectorum available to mitigate its effect 
on L. papilliferum and its synergistic interactions with frequent 
wildfires to a degree sufficient that we would consider it no longer a 
threat to the species.

Climate Change

    (10) Comment: One commenter indicated that the effects of global 
warming and climate change on the species must be considered in our 
analyses of potential threats to the species and its habitat.
    Our Response: We agree, and have provided a discussion of the 
potential impacts of climate change on Lepidium papilliferum in this 
rule. In brief, there is compelling scientific evidence that we are 
living in a time of rapid, worldwide climate change. For example, 11 of 
the last 12 years evaluated (1995-2006) rank among the 12 warmest years 
in the instrumental record of global surface temperature (since 1850) 
(ISAB 2007, p. iii). While the effects of global climate change are 
uncertain, it has the potential to affect rare plants and their 
habitats, including L. papilliferum. Although the Service cannot 
identify specific potential effects on the species at this time, some 
models indicate that climate change may

[[Page 52059]]

provide an environment conducive to further conversion of the 
sagebrush-steppe ecosystem by invasive nonnative annual grasslands, 
which would have negative consequences for L. papilliferum; fire 
frequency and extent is predicted to increase as well. Although we do 
not consider climate change to pose a significant threat to L. 
papilliferum in and of itself, we do consider climate change to be a 
potentially important contributing factor to the primary threats of 
frequent wildfire and invasive nonnative plants, particularly B. 
tectorum, and especially in regard to our evaluation of the likelihood 
of the continuation of these threats into the foreseeable future. A 
complete description of the potential effects from climate change and 
our evaluation of this threat is found in Factor E of the Summary of 
Factors Affecting the Species discussion.

Livestock Grazing

    (11) Comment: Two commenters provided information to support the 
argument that livestock grazing is detrimental to Lepidium 
papilliferum. Four commenters provided comment or new information to 
support the countering view, indicating that livestock grazing is not 
detrimental or could be beneficial to the species.
    Our Response: Livestock use in areas that contain Lepidium 
papilliferum has the potential to result in either positive or negative 
effects on the species, depending on a variety of factors such as 
stocking rates and season of use. The most visible negative effect on 
L. papilliferum and its slickspot habitat is from mechanical 
disturbance due to trampling, which can affect the fragile soil layers 
of slickspots and compromise their integrity and function (Seronko 
2004; Meyer et al. 2005, pp. 21-22). Livestock trampling and compaction 
of slickspots may also bury seeds to such a depth that germination is 
no longer possible (Meyer et al. 2005, pp. 21-22). We are aware of 
three incidents where livestock trampling events have apparently 
resulted in a dramatic decrease in L. papilliferum numbers at sites 
where the plants were formerly abundant, while reduced plant numbers 
were not observed at similar adjacent sites within the same year 
(Robertson 2003b, p. 8; Meyer et al. 2005, p.22; Colket 2006, pp. 10-
11). Lepidium papilliferum numbers are slowly recovering at the site in 
the Boise Foothills (Colket 2009, p. 31), the site at the OTA has shown 
no apparent recovery over time (Meyer et al. 2005, p.22), and the fate 
of the third site at Glenns Ferry is unknown, as it has not been 
revisited since the event.
    Conversely, it is hypothesized that livestock use, at an 
appropriate level and season, may reduce the effect of invasive 
nonnative annual grasses at some L. papilliferum sites by reducing fine 
fuel loads, thereby decreasing the risk of wildfire (e.g., Loeser et 
al. 2007, p. 94, and references therein; Launchbaugh et al. 2008; 
Romero-Calcerrada et al. 2008, p. 351). Data limitations currently make 
it difficult to establish effect thresholds from livestock management 
activities on L. papilliferum and its habitat. There have been adaptive 
management techniques implemented for livestock use in some areas 
occupied by L. papilliferum, and several recent studies have examined 
the relationship between livestock trampling effects and L. 
papilliferum abundance (Popovich 2009; Salo 2009; Sullivan and Nations 
2009). As described in detail in ``Livestock Use'' under Factor A in 
the Summary of Factors Affecting the Species section, above, we 
consider the risks associated with livestock use, as currently 
practiced, to be a lesser threat than other factors that have been 
demonstrated to adversely impact the species rangewide. We encourage 
the continued implementation of conservation measures and associated 
monitoring to ensure potential impacts of livestock trampling to the 
species are avoided or minimized.

Data Quality and Interpretation

    (12) Comment: There were several comments regarding the use of 
available monitoring and survey data in determining the historical and 
existing distribution, population size, and trend information for 
Lepidium papilliferum. One commenter and one peer reviewer stated that 
there have been no comprehensive systematic surveys for L. 
papilliferum, and therefore, we do not fully understand the 
distribution or status of the species. In addition, the peer reviewer 
indicated that the number of element occurrences has increased between 
1998 (45 extant EOs) and 2008 and will continue to increase. One 
commenter suggested that the data demonstrate a negative population 
trend for L. papilliferum; other commenters suggested the data are 
inconclusive, and no trend can be determined. Several commenters cited 
information relating L. papilliferum annual abundance to precipitation. 
One commenter and one peer reviewer stated that the Service's 
determination that there is evidence of a statistically significant 
population decline ignores the fact that 2008 was the highest 
population year on record. Another peer reviewer expressed a lack of 
confidence that the high number of plants in 2008 portends any long-
term increase in the population. One commenter stated that the high L. 
papilliferum numbers documented in 2008 agree with the Service's 2007 
conclusion that the overall population trend for the species is 
inconsistent. Two commenters and one peer reviewer stated that the 
Service should be transparent in the quality and source of the data 
used in making our determination.
    Our Response: As previously stated, we have reviewed and considered 
scientific and commercial data contained in numerous technical reports, 
published journal articles, and other documents. We must base our 
listing determination for Lepidium papilliferum on the best available 
data regarding the plant's current known population status, the known 
condition of its habitat, and the current factors affecting the 
species, along with ongoing conservation efforts, as described in the 
Summary of Factors Affecting the Species section of this final 
determination. We acknowledge that uncertainties exist; however, 
section 4 of the Act mandates that we make a listing determination 
based on the best scientific and commercial available at the time of 
our determination.
    Our response is grouped by the following topics: Survey efforts, 
population trends, 2008 HIP survey results, and data quality and 
transparency.
    Survey Efforts: As systematic rangewide surveys have not occurred, 
we agree that undiscovered sites occupied by L. papilliferum likely 
exist. Inventories for L. papilliferum have not been completed on the 
majority of private lands within its range due to restricted access. 
However, occupied slickspot sites and EOs discovered since 1998 have 
not added substantially to our knowledge of where the species exists; 
these new sites have all been within the known range of the species. 
For example, an inventory survey on BLM lands in the Owyhee Plateau 
physiographic region in 2007 documented 200 slickspots containing L. 
papilliferum plants within the known range of the plant (ERO 2008, p. 
7). See our response to State of Idaho comments for additional 
information on potential L. papilliferum survey areas based on a recent 
modeling effort.
    Population Trends: Please see our response to peer review comments, 
number 1, above.
    2008 HIP Survey Results: Rangewide, more slickspot peppergrass 
plants were counted in 2008 than in any other of the 5 years of HIP 
monitoring (Colket 2009, p. 26). This result was largely based on

[[Page 52060]]

substantial increases in the number of slickspot peppergrass plants at 
only 6 of the 80 HIP transects (008A, 027A, 027D, 066, 067, and 070). 
Sixty-six percent of all slickspot peppergrass plants counted in 2008 
(27,544 out of 41,672 plants) occurred at these 6 HIP transects, which 
represent only 8 percent of the total number of HIP transects rangewide 
(Colket 2009, p. 26). Two of the HIP transects with high plant numbers 
in 2008 (066 and 070) are located in the Boise Foothills physiographic 
region. The four remaining HIP transects with high plant numbers in 
2008 were located on the Snake River Plain physiographic region, with 
three of these transects being located on the OTA (027A, 027D, 067). We 
cannot explain why these six transects exhibited such high plant 
numbers in 2008, but it should be noted that each of these six HIP 
transects are located in areas where the plant community is unburned 
and is dominated by the native sagebrush Artemisia tridentata (Colket 
2009, p. 26). Sites exhibiting these characteristics are considered 
high quality habitat for L. papilliferum.
    Data Quality and Transparency: In compiling this document, we tried 
to present the information in an accurate, clear, complete, and 
unbiased manner. Given that the data available on this species covered 
a wide spectrum from peer-reviewed literature to personal 
communications, we developed this document with the goal of providing a 
high degree of transparency regarding the source of data. We followed 
the Service's Information Quality Act Guidelines in developing this 
document (USFWS 2007. These guidelines provide direction for ensuring 
and maximizing the quality of information disseminated to the public. 
The guidelines define quality as an encompassing term that includes 
utility, objectivity, and integrity. Utility refers to the usefulness 
of the information to its intended users, including the public. 
Objectivity includes disseminating information in an accurate, clear, 
complete, and unbiased manner and ensuring accurate, reliable, and 
unbiased information. If data and analytic results have been subjected 
to formal, independent peer review, we generally presume that the 
information is of acceptable objectivity. Integrity refers to the 
security of information, i.e., protection of the information from 
unauthorized access or revision to ensure that the information is not 
compromised through corruption or falsification. One of our goals in 
obtaining public comment and peer review of new information available 
on Lepidium papilliferum since January 2007 was to ensure that we were 
considering the best available data while accurately representing the 
source of the information. Background information on the taxonomy, 
distribution, abundance, life history, conservation actions, and needs 
of L. papilliferum, and threats affecting the species, were derived 
from previous petition findings, previous Federal Register notices, 
Idaho's Natural Heritage Program (formerly Idaho Conservation Data 
Center) EO records, and other pertinent references from 1897 (when the 
species was first collected) through April of 2009.

State of Idaho Comments

    (13) Comment: The State of Idaho requested the Service conduct an 
independent review of available information, including: a third-party 
audit of the monitoring and survey information collected by the IDARNG 
and other researchers at the OTA; re-examine the prior inferences the 
Service has drawn from available information; apply statistical 
analysis to the available information; and evaluate whether there are 
more, currently undiscovered populations.
    Our Response: Prior to making our determination in this final rule, 
the Service has considered all of these issues and conducted the 
reviews suggested by the State; the results of all of these reviews 
were made available during the most recent comment period on the 
proposed rule to list Lepidium papilliferum. During the fall of 2008, 
the Service contracted with independent consultants to evaluate the 
various monitoring and survey methodologies for L. papilliferum and 
conduct statistical analyses on data collected on the OTA since 1990. 
The consultants also analyzed the rangewide HIP data collected over the 
past 5 years to examine any trends in L. papilliferum abundance in 
relation to environmental parameters measured as part of the HIP 
monitoring. In total, the consultants examined the four ongoing L. 
papilliferum survey programs conducted on the OTA. Three of the survey 
programs are conducted solely on the OTA, and two of these (rough 
census and special-use plots) have been implemented at the same 
locations since the early 1990s. The third program is a block search 
that looks at both new and previously surveyed areas for unknown 
populations of L. papilliferum. The fourth survey and monitoring 
program, partially conducted at the OTA, is the rangewide HII and HIP 
monitoring that has been performed by the INHP since the late 1990s. 
The results of this independent analysis were reported in a document 
titled: Analysis of slickspot peppergrass (Lepidium papilliferum) 
population trends on Orchard Training Area and Rangewide Implications, 
cited here as Sullivan and Nations (2009). The Sullivan and Nations 
(2009) report, as well as a report on the statistical and geospatial 
analysis of data collected during the 2000-2002 field surveys at the 
Inside Desert of the Owyhee Plateau (Popovich 2009), and a contracted 
geospatial analysis of wildfire and vegetation types within the range 
of L. papilliferum (Stoner 2009), were provided to the six peer 
reviewers and made available to the public for consideration and 
evaluation of all best available scientific and commercial data during 
the second comment period, and the results of these independent reports 
and reviews were incorporated into this final rule.
    In an effort to evaluate the probability that Lepidium papilliferum 
may be found in other areas, the Service requested the INHP develop a 
model for predicting L. papilliferum distribution based on factors such 
as elevation, soil types, precipitation, and underlying geology (Colket 
2008, p. 2). This model identified several potential areas in southwest 
Idaho with a relatively high probability of supporting L. papilliferum 
in areas outside the known range of the species. Although preliminary 
surveys of these areas did not result in the discovery of additional L. 
papilliferum sites (Colket 2008, pp. 4-6), we believe that this model 
can be used as a tool to prioritize areas targeted for future surveys 
and conservation planning efforts for L. papilliferum (Colket 2008, p. 
7). Past searches have occurred for this species in Oregon (Findley 
2003) and outside of its known range in Idaho (BLM 2000), but the 
species has never been found in these areas. The BLM is aware of our 
interest in the possible location of L. papilliferum in Oregon, and 
their botanists continue to look for the species during the course of 
their surveys (Foss 2009), but to date it has not been found. The best 
currently available information does not indicate that there has been a 
significant increase in the known range of L. papilliferum since our 
2007 decision.
    In the past, questions were raised regarding why expanded surveys 
on the OTA conducted by URS in 2005 recorded higher numbers of Lepidium 
papilliferum than had been previously observed. Sullivan and Nations 
(2009) were able to clarify that the large number of L. papilliferum 
plants counted by URS likely resulted from a more intensive search 
effort over a larger area in 2005 compared to what is normally examined 
during the rough

[[Page 52061]]

census or special-use plot monitoring efforts (Sullivan and Nations 
2009, p. 2). Although this survey indicated that there were more L. 
papilliferum on the OTA than previously documented, it did not increase 
the known range of the species.

Available Conservation Measures

    Conservation measures provided to species listed as endangered or 
threatened under the Act include recognition of the status, increased 
priority for research and conservation funding, recovery actions, 
requirements for Federal protection, and prohibitions against certain 
practices. Recognition through listing results in public awareness and 
conservation by Federal, State, and local agencies, private 
organizations, and individuals. The listing of Lepidium papilliferum 
will lead to the development of a recovery plan for the species. Under 
section 6 of the Act, we would be able to grant funds to the State of 
Idaho for management actions promoting the conservation of L. 
papilliferum. A full discussion of the ongoing conservation actions by 
Federal, State, and local entities involved with Lepidium papilliferum 
conservation is described elsewhere in this document (see Evaluation of 
Conservation Efforts, above).
    The Act requires Federal agencies to implement recovery actions, as 
well as encourages non-Federal entities to support and carry out 
recovery goals for listed species. The protection measures required of 
Federal agencies and the prohibitions against certain activities 
involving listed plants are discussed, in part, below.
    Section 7(a) of the Act, as amended, requires Federal agencies to 
evaluate their actions with respect to any species that is proposed or 
listed as endangered or threatened and with respect to its critical 
habitat, if any is designated or proposed for designation. Regulations 
implementing this interagency cooperation provision of the Act are 
codified at 50 CFR Part 402. Section 7(a)(2) requires Federal agencies, 
including the Service, to ensure that activities they authorize, fund, 
or carry out are not likely to jeopardize the continued existence of a 
listed species or to destroy or adversely modify its critical habitat 
if any has been designated. If a Federal action may affect a listed 
species or its critical habitat, the responsible Federal agency must 
consult with us under the provisions of section 7(a)(2) of the Act.
    For Lepidium papilliferum, Federal agency actions that may require 
consultation as described in the preceding paragraph may include 
actions that would affect slickspot soil integrity or function, 
individual L. papilliferum plants, or the seed bank of the plant. Such 
actions may include, but are not limited to: soil stabilization and 
rehabilitation activities; wildfire suppression and rehabilitation 
activities; construction and maintenance of infrastructure such as 
roads, electronic transmission lines, radio towers, and buildings; 
livestock grazing permits and other Federal permitting actions; 
livestock range improvements by the BLM; or actions undertaken by 
branches of the Department of Defense, U.S. Army Corps of Engineers, 
Federal Emergency Management Agency, and the Federal Highways 
Administration. Section 7 consultation may also be required by the 
provision of Federal funds to State and private entities through 
Federal programs such as the Service's Partners for Fish and Wildlife 
Program and Federal Aid in Wildlife Restoration Program, and a variety 
of grants administered by the U.S. Department of Agriculture, Natural 
Resources Conservation Service, the Federal Housing Administration, and 
the Farm Services Agency. Other activities that may require 
consultation include military training activities by the Air Force or 
the Idaho Army National Guard. Federal actions not affecting the 
species, as well as actions on non-Federal lands that are not federally 
funded, authorized, or permitted, do not require section 7 
consultation, although the latter are still potentially subject to 
section 9's prohibitions.
    The Act and its implementing regulations set forth a series of 
general prohibitions and exceptions that apply to all threatened 
plants. All prohibitions of section 9(a)(2) of the Act, implemented by 
50 CFR 17.71, apply to both endangered and threatened species. These 
prohibitions, in part, make it illegal for any person subject to the 
jurisdiction of the United States to import or export, transport in 
interstate or foreign commerce in the course of a commercial activity, 
sell or offer for sale in interstate or foreign commerce, or remove and 
reduce the species to possession from areas under Federal jurisdiction. 
In addition, for plants listed as endangered, the Act prohibits the 
malicious damage or destruction on areas under Federal jurisdiction and 
the removal, cutting, digging up, or damaging or destroying of such 
plants in knowing violation of any State law or regulation, including 
State criminal trespass law. Section 4(d) of the Act allows for the 
provision of such protection to threatened species through regulation. 
This protection may apply to this species in the future if regulations 
are promulgated. Seeds from cultivated specimens of threatened plants 
are exempt from these prohibitions provided that their containers are 
marked ``Of Cultivated Origin.'' Certain exceptions to the prohibitions 
apply to agents of the Service and State conservation agencies.
    The Act and 50 CFR 17.72 also provide for the issuance of permits 
to carry out otherwise prohibited activities involving threatened 
plants under certain circumstances. Such permits are available for 
scientific purposes and to enhance the propagation or survival of the 
species. For threatened plants, permits also are available for 
botanical or horticultural exhibition, educational purposes, or special 
purposes consistent with the purposes of the Act. We anticipate that 
few trade permits will ever be sought or issued for Lepidium 
papilliferum because the species is not in cultivation or common in the 
wild. Requests for copies of the regulations regarding listed species 
and inquiries about prohibitions and permits may be addressed to U.S. 
Fish and Wildlife Service, Endangered Species Permits, 911 NE. 11th 
Avenue, Portland, OR 97232-4181.
    We adopted a policy on July 1, 1994 (59 FR 34272), to identify to 
the maximum extent practicable at the time a species is listed those 
activities that would or would not constitute a violation of section 9 
of the Act. The intent of this policy is to increase public awareness 
of the effect of the listing on future and ongoing activities within a 
species' range. We believe that based upon the best available 
information, the actions listed below would not result in a violation 
of section 9 of the Act provided these activities are carried out in 
accordance with existing regulation and permit requirements:
    (1) Activities authorized, funded, or carried out by Federal 
agencies (e.g., grazing management, agricultural conversions, range 
management, rodent control, mineral development, road construction, 
human recreation, pesticide application, controlled burns) and 
construction/maintenance of facilities (e.g., fences, power lines, 
pipelines, utility lines) when such activity is conducted according to 
any reasonable and prudent measures prescribed by the Service in a 
consultation conducted under section 7 of the Act; and
    (2) Casual, dispersed human activities on foot (e.g., bird 
watching, sightseeing, photography, and hiking).
    The actions listed below may potentially result in a violation of

[[Page 52062]]

section 9 of the Act; however, possible violations are not limited to 
these actions alone:
    (1) Unauthorized collecting of the species on Federal Lands;
    (2) Interstate or foreign commerce and import/export without 
previously obtaining an appropriate permit.
    Permits to conduct activities are available for purposes of 
scientific research and enhancement of propagation or survival of the 
species.
    Questions regarding whether specific activities, such as changes in 
land use, will constitute a violation of section 9 should be directed 
to the Idaho Field Office (see ADDRESSES section).

Critical Habitat

    Critical habitat is defined in section 3 of the Act as: ``(i) The 
specific areas within the geographical area occupied by the species, at 
the time it is listed in accordance with the provisions of section 4 of 
this Act, on which are found those physical or biological features (I) 
essential to the conservation of the species and (II) which may require 
special management considerations or protection; and (ii) specific 
areas outside the geographical area occupied by the species at the time 
it is listed in accordance with the provisions of section 4 of the Act, 
upon a determination by the Secretary of the Interior that such areas 
are essential for the conservation of the species'' (16 U.S.C. 
1532(5)(A)).
    Conservation, as defined under section 3(3) of the Act, means ``the 
use of all methods and procedures which are necessary to bring any 
endangered or threatened species to the point at which the measures 
provided under this Act are no longer necessary. Such methods and 
procedures include, but are not limited to, all activities associated 
with scientific resources management such as research, census, law 
enforcement, habitat acquisition and maintenance, propagation, live 
trapping, and transplantation, and, in the extraordinary case where 
population pressures within a given ecosystem cannot be otherwise 
relieved, may include regulated taking'' (16 U.S.C. 1532(3)).
    The primary regulatory effect of critical habitat is the 
requirement, under section 7(a)(2) of the Act, that Federal agencies 
shall ensure that any action they authorize, fund, or carry out is not 
likely to result in the destruction or adverse modification of 
designated critical habitat. Section 7(a)(2) of the Act requires 
consultation on Federal actions that may affect critical habitat. The 
designation of critical habitat does not affect land ownership or 
establish a refuge, wilderness, reserve, preserve, or other 
conservation area. Such designation does not allow the government or 
public to access private lands. Such designation does not require 
implementation of restoration, recovery, or enhancement measures by 
private landowners. Where a landowner requests Federal agency funding 
or authorization for an action that may affect a listed species or 
critical habitat, the consultation requirements of section 7(a)(2) of 
the Act would apply, but even in the event of a destruction or adverse 
modification finding, the landowner's obligation is not to restore or 
recover the species, but to implement reasonable and prudent 
alternatives to avoid destruction or adverse modification of critical 
habitat.
    For inclusion in a critical habitat designation, the habitat within 
the geographical area occupied by the species at the time of listing 
must contain the physical and biological features essential to the 
conservation of the species, and be included only if those features may 
require special management considerations or protection. Critical 
habitat designations identify, to the extent known using the best 
scientific data available, habitat areas that provide essential life 
cycle needs of the species (i.e., areas on which are found the primary 
constituent elements (PCEs) laid out in the appropriate quantity and 
spatial arrangement for the conservation of the species). Under the 
Act, we can designate critical habitat in areas outside the 
geographical area occupied by the species at the time it is listed only 
when we determine that those areas are essential for the conservation 
of the species.
    Section 4 of the Act requires that we designate critical habitat on 
the basis of the best scientific and commercial data available. 
Further, our Policy on Information Standards Under the Endangered 
Species Act (59 FR 34271; July 1, 1994), the Information Quality Act 
(section 515 of the Treasury and General Government Appropriations Act 
for Fiscal Year 2001 (Pub. L. 106-554; H.R. 5658)), and our associated 
Information Quality Guidelines issued by the Service, provide criteria, 
establish procedures, and provide guidance to ensure that our decisions 
are based on the best scientific data available. They require our 
biologists, to the extent consistent with the Act and with the use of 
the best scientific data available, to use primary and original sources 
of information as the basis for recommendations to designate critical 
habitat.
    When we are determining which areas should be designated as 
critical habitat, our primary source of information is generally the 
information developed during the listing process for the species. 
Additional information sources may include the recovery plan for the 
species, articles in peer-reviewed journals, conservation plans 
developed by States and counties, scientific status surveys and 
studies, biological assessments, or other unpublished materials and 
expert opinion or personal knowledge.

Prudency Determination

    Section 4(a)(3) of the Act, as amended, and implementing 
regulations (50 CFR 424.12), require that, to the maximum extent 
prudent and determinable, the Secretary designate critical habitat at 
the time a species is determined to be endangered or threatened. Our 
regulations (50 CFR 424.12(a)(1)) state that the designation of 
critical habitat is not prudent when one or both of the following 
situations exist: ``(i) [t]he species is threatened by taking or other 
human activity, and identification of critical habitat can be expected 
to increase the degree of such threat to the species, or ii) [s]uch 
designation of critical habitat would not be beneficial to the 
species.''
    There is no documentation that Lepidium papilliferum is threatened 
by taking or other human activity. In the absence of finding that the 
designation of critical habitat would increase threats to a species, if 
there are any benefits to a critical habitat designation, then a 
prudent finding is warranted. The potential benefits include: (1) 
Triggering consultation under section 7 of the Act for actions in which 
there may be a Federal nexus where it would not otherwise occur 
because, for example, the area is or has become unoccupied or the 
occupancy is in question; (2) focusing conservation activities on the 
most essential features and areas; (3) providing educational benefits 
to State or county governments or private entities; and (4) preventing 
people from causing inadvertent harm to the species.
    The primary regulatory effect of a critical habitat designation is 
the section 7(a)(2) requirement that Federal agencies refrain from 
taking any action that destroys or adversely affects critical habitat. 
At present, the known extant individuals of Lepidium papilliferum occur 
on Federal, State, and private land, and all previously known 
occurrences have been on Federal, State, and private lands. State and 
private lands that may be designated as critical habitat in the future 
for this species may be subject to Federal actions that trigger

[[Page 52063]]

the section 7 consultation requirement, such as the granting of Federal 
monies for conservation projects or the need for Federal permits for 
projects. Therefore, since we have determined that the designation of 
critical habitat will not likely increase the degree of threat to the 
species and may provide some measure of benefit, we find that 
designation of critical habitat is prudent for L. papilliferum.

Critical Habitat Determinability

    As stated above, section 4(a)(3) of the Act requires the 
designation of critical habitat concurrently with the species' listing 
``to the maximum extent prudent and determinable'' (16 U.S.C. 
1533(a)(3)). Our regulations at 50 CFR 424.12(a)(2) state that critical 
habitat is not determinable when one or both of the following 
situations exist:
    (i) Information sufficient to perform required analyses of the 
impacts of the designation is lacking, or
    (ii) The biological needs of the species are not sufficiently well 
known to permit identification of an area as critical habitat.
    When critical habitat is not determinable, the Act provides for an 
additional year to publish a critical habitat designation (16 U.S.C. 
1533(b)(6)(C)(ii)).
    In accordance with section 3(5)(A)(i) of the Act and regulations at 
50 CFR 424.12, in determining which areas occupied by the species at 
the time of listing to designate as critical habitat, we consider those 
physical and biological features essential to the conservation of the 
species that may require special management considerations or 
protection. We consider the physical or biological features to be the 
PCEs laid out in the appropriate quantity and spatial arrangement for 
the conservation of the species. The PCEs listed at 50 CFR 424.12(b) 
include, but are not limited to:
    (1) Space for individual and population growth and for normal 
behavior;
    (2) Food, water, air, light, minerals, or other nutritional or 
physiological requirements;
    (3) Cover or shelter;
    (4) Sites for breeding, reproduction, rearing of offspring, 
germination, or seed dispersal; and generally
    (5) Habitats that are protected from disturbance or are 
representative of the historic geographical and ecological 
distributions of a species.
    Although we have determined that the designation of critical 
habitat is prudent for Lepidium papilliferum, new and revised 
information received since the 2007 withdrawal notice (72 FR 1622) has 
to be evaluated to determine the physical and biological features that 
may be essential for the conservation of the species in those areas 
that were occupied at the time of listing, or areas that may be 
essential to the conservation of the species outside of the area 
occupied at the time of listing. For example, we have received new 
information regarding the effects of seed predation indicating that 
this emerging threat may have a serious impact on the long-term 
viability of L. papilliferum. However, our current understanding of the 
overall significance of this threat is limited by its recent discovery 
and having only short-term evaluation results available. We also have 
new information indicating that competition with nonnative plants in 
slickspots has a significant impact on the ability of L. papilliferum 
to persist in these specialized microsites. A thoughtful assessment of 
the designation of critical habitat will require additional time to 
evaluate the physical and biological features essential to the 
conservation of the species in light of our new understanding of these 
emerging threats. Therefore, we find that critical habitat for L. 
papilliferum is not determinable at this time.

Required Determinations

Paperwork Reduction Act of 1995 (44 U.S.C. 3501 et seq.)

    This rule does not contain any new collections of information that 
require approval by Office of Management and Budget (OMB) under the 
Paperwork Reduction Act. This rule will not impose recordkeeping or 
reporting requirements on State or local governments, individuals, 
businesses, or organizations. An agency may not conduct or sponsor, and 
a person is not required to respond to, a collection of information 
unless it displays a currently valid OMB control number.

National Environmental Policy Act

    We have determined that we do not have to prepare environmental 
assessments and environmental impact statements, as defined under the 
authority of the National Environmental Policy Act of 1969 (42 U.S.C. 
4321 et seq.), in connection with regulations we issued under section 
4(a) of the Act. We published a notice outlining our reasons for this 
determination in the Federal Register on October 25, 1983 (48 FR 
49244).

References Cited

    A complete list of all references cited herein is available on the 
Internet at http://www.regulations.gov. In addition, a complete list of 
all references cited herein, as well as others, is available upon 
request from the Idaho Fish and Wildlife Office (see FOR FURTHER 
INFORMATION CONTACT).

Authors

    The primary authors of this document are staff members of the Idaho 
Fish and Wildlife Office, U.S. Fish and Wildlife Service (see 
ADDRESSES).

List of Subjects in 50 CFR Part 17

    Endangered and threatened species, Exports, Imports, Reporting, and 
recordkeeping requirements, Transportation.

Regulation Promulgation

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Accordingly, we amend part 17, subchapter B of chapter I, title 50 of 
the Code of Federal Regulations, as follows:

PART 17--[AMENDED]

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1. The authority citation for part 17 continues to read as follows:

    Authority: 16 U.S.C. 1361-1407; 16 U.S.C. 1531-1544; 16 U.S.C. 
4201-4245; Pub. L. No. 99-625, 100 Stat. 3500; unless otherwise 
noted.

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2. Amend Sec.  17.12(h) by adding the following entry to the List of 
Endangered and Threatened Plants in alphabetical order under 
``Flowering Plants'':
    Sec.  17.12 Endangered and threatened plants.
* * * * *
    (h) * * *

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                    Species
------------------------------------------------  Historic range        Family            Status         When listed        Critical      Special rules
       Scientific name            Common name                                                                               habitat
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                                                                    FLOWERING PLANTS
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                                                                      * * * * * * *
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[[Page 52064]]

 
Lepidium papilliferum          Slickspot         U.S.A. (ID)       Brassicaceae      T                 765              NA               NA
                                peppergrass
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* * * * *

    Dated: September 24, 2009
Daniel M. Ashe
Deputy Director, Fish and Wildlife Service
[FR Doc. E9-24039 Filed 10-7-09; 8:45 am]
BILLING CODE 4310-55-S