[Federal Register Volume 72, Number 8 (Friday, January 12, 2007)]
[Proposed Rules]
[Pages 1622-1644]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 07-60]



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Part III





 Fish and Wildlife Service





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50 CFR Parts 17



 Endangered and Threatened Wildlife and Plants; Withdrawal of Proposed 
Rule To List Lepidium papilliferum (Slickspot Peppergrass); Proposed 
Rule

  Federal Register / Vol. 72, No. 8 / Friday, January 12, 2007 / 
Proposed Rules  

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DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17

RIN 1018-AU99


Endangered and Threatened Wildlife and Plants; Withdrawal of 
Proposed Rule To List Lepidium papilliferum (Slickspot Peppergrass)

AGENCY: Fish and Wildlife Service, Interior.

ACTION: Proposed rule; withdrawal.

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SUMMARY: We, the U.S. Fish and Wildlife Service (Service), again 
withdraw our July 15, 2002, proposal (67 FR 46441) to list Lepidium 
papilliferum (slickspot peppergrass) as an endangered species under the 
Endangered Species Act of 1973, as amended (Act). The best available 
data for L. papilliferum indicates that, while its sagebrush-steppe 
matrix habitat is degraded, there is little evidence of negative 
impacts on the abundance of L. papilliferum, which inhabits slickspot 
microsites within this system. Annual abundance of the plant is 
strongly correlated with spring precipitation, therefore a high degree 
of variability in annual abundance is to be expected. Data on overall 
population trends are inconsistent; although recent declines that do 
not correlate with spring rainfall are noted in one portion of the 
species' range, range-wide data demonstrate increases in abundance that 
continue to track consistently with rainfall during those same years. 
The best available range-wide data indicate that abundance of the 
population range-wide is strongly correlated with precipitation and has 
increased in recent years in association with increased rainfall, as 
expected.

ADDRESSES: Supporting documentation for this action is available for 
public inspection, by appointment, during normal business hours at the 
Snake River Fish and Wildlife Office, 1387 S. Vinnell Way, Boise, ID 
83709.

FOR FURTHER INFORMATION CONTACT: Jeffery Foss, Field Supervisor, Snake 
River Fish and Wildlife Office at the above address; by telephone at 
208/378-5243; by facsimile at 208/378-5262; or by electronic mail at: 
[email protected].

SUPPLEMENTARY INFORMATION:

Species Information

    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 (Hitchcock et al. 1964, p. 516; 
Hitchcock and Cronquist 1973). In a review of taxa in the mustard 
family (Brassicaceae), Rollins (1993) maintained the species based on 
differences in the physical features between L. papilliferum and L. 
montanum. More recently, a taxonomic review concluded that L. 
papilliferum warrants species recognition based on distinct 
morphological features (Lichvar 2002), and a contrasting life history 
when compared to L. montanum regarding seed dormancy and its seed bank 
(Meyer et al. 2005, p. 21). The preliminary results of recent 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). 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), 2006).

Biology

    Lepidium papilliferum is a taprooted, intricately branched plant. 
The plant flowers once and then dies (it is monocarpic), and displays 
two different life cycles, an annual and a biennial form. The plant 
averages 2 to 8 inches (in) (5 to 20 centimeters (cm)), but can reach 
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 millimeter (mm)) diameter, white, and 4-
petalled. Fruits (siliques) are 0.1 in (3 mm), round in outline, 
flattened, and 2-seeded (Moseley 1994, pp. 3 and 4; Holmgren et al. 
2005, p. 260).
    The annual form of the Lepidium papilliferum matures, reproduces by 
setting seed, and dies in one growing season. The biennial life form 
initiates growth in the first year as a rosette, but does not produce 
seed and die until the second year. Biennial rosettes must survive dry 
summers on the Snake River Plain and Owyhee Plateau, and consequently 
many of these rosettes die before flowering and producing seed. The 
proportion of annuals versus biennials in a population can vary greatly 
(Meyer et al. 2005, p. 15). Depending on individual plant vigor and the 
effectiveness of pollination, dozens, if not thousands, of seeds can be 
produced by a single L. papilliferum plant (Quinney 1998, pp. 15 and 
17), with individual biennial plants producing a much greater number of 
seeds than annual plants (Meyer et al. 2005, p. 15). Average seed 
output for annual plants at the Orchard Training Area (OTA) (an Idaho 
Army National Guard training area on BLM land) in 1993, was 125 seeds 
per plant, and in 1994, was 46 seeds per plant. Biennial seed 
production in 1993 and 1994 averaged 787 and 105 seeds per plant, 
respectively (Meyer et al. 2005, p. 16).
    Lepidium papilliferum 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 seeds produced in a given 
year germinate annually and approximately 3 percent die annually (Meyer 
et al. 2005, pp. 17, 18). After 12 years, all seeds in a given cohort 
will likely have either died or germinated (Meyer et al. 2005, p. 18). 
Seeds are released in late June or early July.
    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). In an analysis of monitoring data, minimum and 
maximum temperatures were not statistically correlated with L. 
papilliferum abundance (Menke and Kaye 2006b, p. 8). 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 apparently in many years constitutes the majority of 
the population (Mancuso and Moseley 1998, p. 1). According to Meyer et 
al. (2005, p. 21), ``Without a persistent seedbank, L. papilliferum 
could probably not succeed as an annual in its stochastically varying 
habitat.'' Seed banks are adaptations for survival in a ``risky 
environment,'' because they buffer a species from stochastic impacts 
such as lack of soil moisture (Baskin and Baskin 2001, p. 160).
    Lepidium papilliferum seeds have an extremely patchy distribution, 
making it difficult to estimate seed density without taking a large 
number of samples (Meyer and Allen 2005, pp. 5, 6). The vast majority 
of L. papilliferum seeds in slickspots (see Ecology and Habitat 
section) have been located near the soil surface, with lower numbers of 
seeds located in deeper soils (Meyer et

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al. 2005, p. 19; Palazzo et al. 2005, p. 3). L. papilliferum seeds have 
been found in slickspots with no above-ground plants (Meyer et al. in 
press, p. 18; Palazzo et al. 2005, p. 10). Viable seeds have also been 
located outside of slickspots, indicating that some seed dispersal is 
occurring beyond slickspot habitat (Palazzo et al. 2005, p. 10). The 
primary seed dispersal mechanism for L. papilliferum has not been 
identified and is not known (Robertson and Ullappa 2004, p. 1708).
    Lepidium papilliferum seeds located near the soil surface show 
higher rates of germination and viability (Meyer and Allen 2005, pp. 6 
to 8; Palazzo et al. 2005, p. 10), and the greatest seedling emergence 
success rate (Meyer and Allen 2005, pp. 6 to 8). Seeds were more 
abundant, more viable, and had greater germination percentages and 
rates from the upper 2 in (5 cm) of soil (Palazzo et al. 2005, pp. 8, 
10). In another study, the highest level (60 percent) of seedling 
emergence was observed at a seed depth of 0.1 in (approximately 2 mm), 
with a marked decrease in seedling emergence at 0.2 in (approximately 5 
mm) (Meyer and Allen 2005, pp. 6, 7).
    Deep burial of slickspot peppergrass seeds (average depths greater 
than 5.5 in (14 cm)) entombs seeds that are still viable and preserves 
them beyond the 12-year period previously assumed as the maximum period 
of viability for Lepidium papilliferum seeds (Meyer and Allen 2005, pp. 
6, 9). While there may be processes such as badger (Taxidea taxus) 
burrow-digging that could return these buried viable seeds to the near-
surface, the successful establishment of seedlings may be reduced due 
to modification of soil layers following previous disturbance events 
(Meyer and Allen 2005, pp. 6, 8). The effects of environmental threats 
such as wildfire on L. papilliferum seed dormancy and viability are 
currently unknown.
    Lepidium papilliferum has low seed set in the absence of 
pollinators, and is primarily an outcrossing species requiring pollen 
from separate plants for more successful fruit production (Robertson 
2003a, p. 5; Robertson and Klemash 2003, p. 339; Robertson and Ulappa 
2004, p. 1707). In pollination experiments where researchers moved 
pollen from one plant to another, fruit production was observed to be 
higher with pollen from distant sources 246 to 330 feet (ft) (75 to 100 
meters (m)) away within a plant patch, and 4 to 12.4 miles (mi) (6.5 to 
20 kilometers (km)) away from another patch of plants (Robertson and 
Ulappa 2004, p. 1705). Genetic exchange can occur either thorough 
pollen or seed dispersal.
    Lepidium papilliferum has been observed to be visited by at least 
25 families of insects, although only some of these insects serve as 
effective pollinators (Robertson 2003b, pp. 10, 11; Robertson and 
Klemash 2003, p. 336). Scarcity of pollinators were not found to limit 
seed set at any site (Robertson et al. 2004, p. 14). Pollinators 
include insects from several families of bees and ants (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). The pollen transfer efficiency 
for L. papilliferum varies among these insects. Pollinators of L. 
papilliferum with high pollen transfer efficiencies and visitation 
rates include sphecid and vespid wasps, bombyliid and tachnid flies, 
and honeybees, with lesser contributions from halictid bees.
    The genetics of Lepidium papilliferum were studied using samples 
collected from areas across the entire range of the species, including 
both the Snake River Plain and a disjunct range on the Owyhee Plateau 
(Stillman et al. 2005, pp. 6, 8, 9). The largest amounts of genetic 
difference occurred between the Snake River Plain and the Owyhee 
Plateau populations. The Snake River Plain and the Owyhee Plateau 
populations are separated by 44 mi (70 km), which is considered beyond 
the distance that insect pollinators can travel or that seed dispersal 
can occur. Despite the distance that separates the Snake River Plain 
and the Owyhee Plateau populations, plants from these two areas share a 
94-percent similarity in allelic diversity. This high degree of 
similarity suggests that they were either part of one continuous 
distribution or they originated from similar ancestral material 
(Stillman et al. 2005, pp. 6, 8, 9). Sites in the Snake River Plain 
with fewer numbers of plants had less genetic diversity than sites with 
larger numbers of plants. Interestingly, a correlation between 
population size and genetic diversity did not exist in the Owyhee 
Plateau region. The authors suggested that this may be because the 
Owyhee Plateau region is less fragmented than the Snake River Plain, 
but suggested further genetic research is needed. Larson (2006, p. 14 
and Fig. 4) also found geographically well-defined populations of 
Lepidium 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).

Ecology and Habitat

    The habitat of Lepidium papilliferum is found within semiarid 
sagebrush-steppe habitats in southern Idaho. This plant is known from 
the extensive volcanic plains of the Snake River Plain (and foothills) 
and the Owyhee Plateau, with most element occurrences (EOs) occurring 
on flat to gently sloping terrain (see Figure 1 below). Element 
occurrences are defined as ``an area of land in which a species is or 
was present'' (NatureServe 2002). L. papilliferum is associated with 
basalt ridges and plains, stable piedmont, and older alluvial 
floodplains and deposits (Fisher et al. 1996, pp. 14, 16).

BILLING CODE 4310-55-C

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[GRAPHIC] [TIFF OMITTED] TP12JA07.000

BILLING CODE 4310-55-P
    Range-wide, Lepidium papilliferum is associated with visually 
distinct microsites known as slickspots (mini-playas or natric sites) 
(Moseley 1994, p. 7). 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); 
little vegetation; more distinct soil layers with a more columnar or 
prismatic structure; higher alkalinity and clay content and natric 
(higher sodium) properties (Fisher et al. 1996, pp. 15, 16; Meyer and 
Allen 2005, pp. 3 to 5, 8); 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). The slickspots range in size from less 
than 10 square feet (ft \2\) (1 square meter (m \2\)) to about 110 ft 
\2\ (10 m \2\) (Mancuso et al. 1998, p. 1), but most are between 10 ft 
\2\ and 20 ft \2\ (1 m \2\ and 2 m \2\).
    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 thorough field inventory within the Juniper Butte Range in 
2002 found that of the 11,070

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acres (ac) (4,480 hectares (ha)) surveyed, approximately 1 percent (109 
ac (44 ha)) consisted of slickspot habitat, and only 4 percent of the 
slickspot habitat was occupied by above-ground L. papilliferum plants 
(U.S. Air Force 2002, p. 9). The total amount of occupied slickspot 
habitat (above-ground plants and known occurrences of seed in the soil) 
within this large occurrence was approximately 4 ac (1.6 ha) at the 
time it was surveyed (0.1 percent of the acreage).
    Based on studies in 2004 on the Orchard Training Area (OTA), a 
training area of the Idaho Army Reserve National Guard (IARNG) on the 
Snake River Plain, slickspots have three primary layers: the surface 
silt layer, the restrictive layer, and the moist clay layer beneath. 
The top two layers (surface silt and restrictive) of slickspots are 
very thin; the surface silt layer varies in 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 moist clay basal 
layer, which continues down to bedrock, is consistently below the 
restrictive layer (Meyer and Allen 2005, p. 3). All slickspots have 
variations in surface silt thickness.
    As part of the Lepidium papilliferum Habitat Integrity and 
Population (HIP) monitoring conducted range-wide in 2005, the depth of 
the surface silt layer was measured 3 times in every slickspot along 79 
transects across the range of L. papilliferum; a total of 769 
slickspots were sampled. Measurements were taken directly adjacent to 
live L. papilliferum plants; the range-wide mean surface silt layer 
depth was 0.31 in (0.78 cm) (Colket 2006a).
    The surrounding sagebrush matrix soils are distinguished from 
slickspot soils by a deeper silt layer with a clay layer beneath, and 
usually the restrictive layer is lacking (Meyer and Allen 2005, pp. 3 
to 5). Non-slickspot soils at the OTA had thick silt layers with a mean 
depth of 4.7 in (12 cm); the silt layer typically transitioned directly 
into the clay layer beneath, although some samples had restrictive 
layers which were abnormally thickened (over 3.9 in (10 cm)) (Meyer and 
Allen 2005, pp. 3 to 5, 8).
    It is unknown how long slickspots take to form, but it is 
hypothesized to take several thousands of years (Nettleton and Petersen 
1983, p. 193; Seronko 2006, p. 1). The conditions that allowed for the 
formation of slickspots in southwestern Idaho are thought to have 
occurred during a wetter Pleistocene climate. Holocene additions of 
wind-carried salts (often loess deposits) produced soils high in sodium 
(natric) (Nettleton and Petersen 1983, p. 191; Seronko 2006, p. 1). It 
may take several hundred years to alter or lose slickspots through 
natural climate change or severe natural erosion (Seronko 2006, p. 1). 
Some researchers hypothesize that, given current climatic conditions, 
new slickspots are no longer being created (Nettleton and Petersen 
1983, pp. 166, 191, 206), but that some slickspots subjected to light 
disturbance in the past may re-form (Seronko 2006, p. 1). Slickspots 
may be destroyed and lost to disturbances that alter the physical 
properties of the soil layers.
    The forces that hold clay particles together are greatly weakened 
when sodium-clay and water come into contact. In this condition, clay 
particles are easily detached or dispersed from larger aggregates, 
i.e., slickspot soils are especially susceptible to mechanical 
disturbances when wet (Rengasmy et al. 1984, p. 63; Seronko 2004, pp. 
1, 2). Such disturbances disrupt the soil layers important to Lepidium 
papilliferum's seed germination and seedling growth. 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 reform similar to their pre-disturbance configuration. 
Slickspots that no longer support L. papilliferum, but still retain the 
thin silt and restrictive layer structure, are the most likely sites to 
support reintroductions. Restoration and species reintroduction 
potential for L. papilliferum habitat have not been studied.
    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)). Average precipitation 
within the species' range is 11.7 in (29.7 cm) for Boise, 7.4 in (18.8 
cm) for Bruneau, and 9.9 in (25.1 cm) for Mountain Home. Precipitation 
tends to fall as rain, primarily in winter and spring (November to 
May); the lowest rainfall occurs in July and August, and June, 
September, and October receive slightly more. Freeze-free days average 
about 120 days in Boise, 146 days in Bruneau, and 138 days in Mountain 
Home (WRCC 2006).
    Spring precipitation has been correlated with above-ground numbers 
of Lepidium papilliferum in several analyses. Palazzo et al. (2005, p. 
9) and Menke and Kaye (2006a, p. 8) utilized Habitat Integrity Index 
(HII) range-wide data collected from 1998 to 2001. Menke and Kaye 
(2006b, pp. 10, 11) utilized HII data collected from 1998 to 2002, as 
well as 2004 Habitat Integrity and Population (HIP) data. Meyer et al. 
(2005, p. 15) utilized demographic data from the OTA collected from 
1993 to 1995. Palazzo et al. (2005, p. 9) found a positive relationship 
(p-value of less than 0.01) between above-ground plants and February to 
June precipitation. Menke and Kaye (2006a, p. 8) found March to May 
precipitation accounted for 99.4 percent (2006a, p. 8) and 89 percent 
(2006b, pp. 10, 11) of the variation in L. papilliferum numbers. 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. This correlation of abundance with spring rainfall is important, 
as it at least partially explains past fluctuations in population 
numbers, and suggests that perceived declines were largely a result of 
years with low precipitation levels. Menke and Kaye (2006b, p. 8) also 
found that minimum and maximum temperatures were not statistically 
correlated with L. papilliferum abundance.
    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. Plant 
ecology literature suggests that plants tolerant of stress (e.g., 
alkaline soils) are poor competitors (Grime 1977, p. 1185).

Range and Distribution

    Lepidium papilliferum is known only from the Snake River Plain and 
its adjacent northern foothills (an area 90 by 25 mi (145 by 40 km)) in 
southwest Idaho, and a disjunct population on the Owyhee Plateau in 
Idaho (see Figure 1 above). 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 to 9). 
The separation of population centers into two physiographic regions is 
important for the conservation of L. papilliferum. We regard the two 
physiographic regions as two distinct metapopulations, the Snake River 
Plain metapopulation and the Owyhee Plateau metapopulation. 
Metapopulation concepts are useful when considering fragmented 
habitats, such as those within L. papilliferum's range, because they 
include discussion of when extinction events exceed colonization 
events, which can cause

[[Page 1626]]

the species to not persist (Husband and Barrett 1996, pp. 461 to 462).
    In 2003, a ``Candidate Conservation Agreement for Slickspot 
Peppergrass (Lepidium papilliferum)'' (CCA) was developed by several 
State, Federal, and private entities in Idaho (State of Idaho et al. 
2003) (see Previous Federal Actions section). The CCA is based on two 
geographical management areas that include known EOs, one on the Snake 
River Plain and a second on the Owyhee Plateau, called ``consideration 
zones.'' Although somewhat arbitrary in nature, this designation is 
useful for management purposes. There are 1,595,205 ac (645,597 ha) 
within the Snake River Plain consideration zone, and 126,946 ac (51,373 
ha) within the Owyhee Plateau consideration zone. Factors affecting the 
species vary between the two physiographic regions. For example, urban 
and rural development, agriculture, and infrastructure development of 
sagebrush-steppe habitat has been substantial within the Snake River 
Plain, but little development has occurred within the Owyhee Plateau 
portion of L. papilliferum's range.
    Element occurrences have been used to describe distribution of 
Lepidium papilliferum by assuming that slickspots within 1 kilometer 
(0.6 mi) of each other are capable of genetic exchange through 
pollination (Colket and Robertson, pers. comm. 2006). As of February 
2006, there were 85 delineated EOs that occupied 13,359 ac (5,406 ha) 
(Colket et al. 2006). We estimate that the actual acreage occupied by 
L. papilliferum is only a fraction of a percent of this total acreage 
number because the majority of slickspots are not occupied by L. 
papilliferum and slickspots occupy a small percentage of the landscape 
(see U.S. Air Force 2002, p. 9, for an example). Of these EOs, 60 
(11,025.3 ac (4,461.8 ha)) occur on the Snake River Plain, and 25 
(2,333.8 ac (944.5 ha)) occur on the Owyhee Plateau (Colket et al. 
2006, Table 14). Of the total EO acreage, 521 ac (211 ha) (3.9 percent) 
occur on private lands, 1,254 ac (507 ha) (9.4 percent) occur on lands 
managed by the State of Idaho, and 11,582 ac (4,687 ha) (86.7 percent) 
occur on Federal lands (USFWS 2006c). On the Snake River Plain, 85 
percent of the EO acreage occurs on federally managed lands, 10.3 
percent of the EO acreage occurs on State-managed lands, and 4.7 
percent of the EO acreage occurs on private lands. On the Owyhee 
Plateau, 94.7 percent of the EO acreage occurs on Federally managed 
lands, with the remaining 5.3 percent occurring on State managed lands; 
no EOs on the Owyhee Plateau occur on private lands.
    The approximate extant range of the plant was first described in 
1994 (Moseley 1994, p. 6), and has not changed substantially since, 
although the amount of known occupied habitat, particularly on the 
Owyhee Plateau, has expanded in recent years. Since 2003, sixteen new 
occurrences, all within 3 mi (4.8 km) of previously existing 
occurrences, have been documented: 2 on the Snake River Plain with an 
area of 2.7 ac (1 ha) and approximately 2,500 individuals, and 14 on 
the Owyhee Plateau with an area of 46.6 ac (18 ha) and approximately 
650 individuals (Colket et al. 2006, Tables and Appendix A). It should 
be noted that not all potential L. papilliferum habitat in southwest 
Idaho has been surveyed, and it is likely that additional occupied L. 
papilliferum sites will be found.
    Estimating the number of individuals (abundance) of Lepidium 
papilliferum is confounded by its annual or biennial life cycle, 
because the number of individuals of each life form can fluctuate 
widely depending on precipitation. To assess abundance, we utilized 
four available data sets: range-wide EO records maintained by the Idaho 
Conservation Data Center (CDC), range-wide data associated with the 
HII/HIP monitoring, transect monitoring data collected on the OTA, and 
special use plot data from the OTA.
    As of February 2006, the Idaho CDC had ranked 101 EO records for 
Lepidium papilliferum (Colket et al. 2006a, pp. 15 to 41); 9 are ranked 
as extirpated (lost) or probably extirpated, and 7 are considered 
historical (information for most is too vague for relocation). All 9 
extirpations were verified locations from old herbarium collections, 
the most recent from 1955, where the habitat has been completely 
converted to urban or agricultural lands (Colket et al. 2006, Table 
13). The remaining 85 records (as of February 2006) are for EOs 
considered extant (existing). In the review of EO specifications and 
ranks conducted in February 2006, observed abundance was categorized as 
being greater than 1,000 plants, 400 to 999 plants, 50 to 399 plants, 
less than 50 plants, 0 plants, or an unknown number of plants. This 
classification was based on the number of plants present at the last 
survey, regardless of year and associated precipitation patterns. 
Existing data provide an estimated abundance for extant EOs: 15 (18 
percent) have over 1,000 plants, 11 (13 percent) have between 400 and 
999 plants, 1 (1 percent) has about 400 plants, 18 (21 percent) have 
between 50 and 399 plants, 22 (26 percent) have fewer than 50 plants, 9 
(11 percent) had no plants at the last visit, and 9 (11 percent) have 
an unknown number of individuals.
    Two monitoring methods, HII and HIP, have been used range-wide for 
Lepidium papilliferum. Each included different methodologies, but are 
still useful for tracking abundance at transects across the two 
efforts. HII monitoring was developed to assess the overall habitat 
condition that includes attributes associated with the slickspots and 
the sagebrush-steppe habitat, occurred for 4 years (1998 to 2001), and 
is presented in various reports (Mancuso and Moseley 1998; Mancuso et 
al. 1998; Mancuso 2000, 2001, 2002; Menke and Kaye 2006a, b). HIP 
monitoring was developed to assess the overall habitat condition that 
includes those attributes associated with the slickspots and the 
sagebrush-steppe habitat, and also the effectiveness of the CCA. HIP 
monitoring was conducted in 2004 and 2005 (State of Idaho et al. 2006, 
p. 18), and is expected to continue. HIP monitoring results in 2004 are 
reported in Menke and Kaye 2006b, and results through 2005 are included 
in our report ``Best Available Biological Information for Slickspot 
Peppergrass (Lepidium papilliferum)'' (USFWS 2006f, Figures 8, 9). 
Although neither the HII nor HIP methodologies have been peer reviewed, 
they represent the best available survey and monitoring techniques for 
L. papilliferum.
    Abundance data for Lepidium papilliferum have been collected range-
wide since 1998, and collected at the OTA since the early 1990s. The 
range-wide HII and HIP transect data illustrate that plant abundance is 
positively correlated with spring precipitation, and specifically that 
rainfall in the months of March through May accounts for 89 percent of 
the variability in plant numbers (Menke and Kaye 2006b, p. 10). Plant 
abundance therefore fluctuates widely between years in association with 
precipitation. In the areas monitored by HII and HIP, Menke and Kaye 
(2006b, p. 10) report that L. papilliferum abundance decreased range-
wide between 1998 and 1999, remained low through 2002, and began to 
increase again beginning in 2002. This pattern closely tracks that of 
rainfall during those same years. Abundance data from transects at the 
OTA illustrate declines in abundance first noted in 1996, with a 
declining trend in recent years that is not correlated with spring 
precipitation (Weaver 2006, pp. 1-6). Abundance data from the range-
wide HII and HIP transects showed increasing trends in L. papilliferum 
between the years 2002 and 2005 (no data were collected in 2003) (USFWS 
2006f, Figures 8, 9).

[[Page 1627]]

Thus range-wide abundance data from the HII and HIP transects continue 
to show a consistently positive correlation with spring precipitation. 
We consider this range-wide data to be the best available at this time.
    We conducted a review of the abundance data and study methodology 
following the reopened comment period on the proposal to list L. 
papilliferum as endangered (October 23, 2006, to November 13, 2006; 71 
FR 62078). A review of the special use plot counts at the OTA (USFWS 
2006e, Figure 7) shows a decline in plant numbers during the drought 
years of 1992 (249 plants), 1997 (624 plants), and 2002 (270 plants) 
followed by a positive response in plant numbers as spring 
precipitation increased in subsequent years 1993 (6,369 plants), 1998 
(3,330 plants), and 2003 (4,080 plants). Reviewing the special use plot 
data at OTA for 2004-2006 illustrates a relatively stable or declining 
number of plants despite increases in spring precipitation.
    We reviewed the OTA population monitoring transect study and 
updated the description of the study methods from our BAI based upon 
clarification of new information provided by IARNG staff during the 
reopened comment period on the proposal to list L. papilliferum as 
endangered (October 23, 2006, to November 13, 2006; 71 FR 62078). The 
BAI cited study methods as described by IARNG staff and stated that the 
census effort occurred annually at the OTA and that observers cover 98 
percent of the plants' habitat at OTA. New information obtained since 
the BAI was written suggests that 90 percent may be a more accurate 
estimate of the amount of habitat surveyed at OTA. Since 2003, 
additional plant inventories have increased the size of the known 
population of L. papilliferum at OTA, including the documentation of 
365 new occupied slickspots in 2005 (URS Corporation 2005, pp. 6-7). 
The OTA population monitoring transects for 2005 reported 18,599 plants 
in the transect areas; the survey inventory by URS corporation reported 
43,925 plants (365 new slickspots with L. papilliferum, 125 historic 
slickspots with L. papilliferum, 66 historic slickspots without L. 
papilliferum) in the areas surveyed at OTA (URS Corporation 2005, p. 
7).
    We reviewed the results of range-wide HII and HIP monitoring, 
including reported plant abundance since these studies were initiated 
in 1998, and new information available to us since the time we last 
issued a listing finding on this species. These data illustrate a 
general pattern of plant numbers correlating with spring precipitation 
(USFWS 2006f, Figures 8, 9). Data are incomplete for 2002 and 2003. 
Menke and Kaye (2006b, p. 19) report that ``populations generally 
decreased during 1998-2004 and these trends appear to be strongly 
influenced by spring precipitation.'' In contrast to the results 
reported from the OTA, range-wide abundance of Lepidium papilliferum as 
measured by the HII and HIP increased as spring precipitation increased 
in the years 2002 through 2005 (USFWS 2006f, Figures 8, 9). Comparing 
years 1998 and 2005, which are relatively comparable in terms of range-
wide spring precipitation (6.6 inches and 6.3 inches, respectively), 
plant numbers are also similar (17,611 and 15,226 respectively), 
indicating little change in overall abundance of L. papilliferum range-
wide over this time interval, despite the intervening fluctuations in 
yearly abundance that are to be expected for an ephemeral annual plant. 
In general, the HII and HIP data from 1998-2005 indicate that the 
abundance of L. papilliferum range-wide remained relatively stable over 
this time interval (USFWS 2006f, Figure 8). We consider this range-wide 
data to be the best available at this time.

Habitat Quality

    Vegetation community data are collected as one component of 
Lepidium papilliferum HIP monitoring. One of the attributes documented 
in HIP monitoring is the fire history pattern. Observations are 
recorded to document if there is evidence of fires at four landscape 
scales; in the HIP transects, and in the surrounding habitat at 65 
meters, 250 meters, and 500 meters from the transect. Given the mosaic 
pattern of wildfire burns, often the surrounding habitat may be burned 
while an individual HIP transect is unburned or predominately unburned. 
In 2004, vegetation communities were sampled at 71 HIP transects, and 
41 (58 percent) of the transects were classified as unburned, with 
predominantly big sagebrush cover and less than 33 percent introduced 
annual cover; 7 (10 percent) were classified as unburned, with moderate 
big sagebrush cover and at least 33 percent introduced annual cover; 6 
(8 percent) were classified as burned, with predominantly native 
vegetation, although introduced annual cover sometimes comprised up to 
50 percent of the total plant cover; 2 (3 percent) were classified as 
burned, with predominantly introduced annual cover (Salsola kali 
(Russian thistle or tumbleweed) and Ceratocephala testiculata (bur 
buttercup, formerly Ranunculus testiculatus)), with low cheatgrass 
(Bromus tectorum) and some crested wheatgrass (Agropyron cristatum); 11 
(14 percent) were classified as burned and dominated by cheatgrass; and 
4 (6 percent) were classified as burned and seeded with crested 
wheatgrass (Colket 2005a, p. 8). In summary, over 42 percent of the HIP 
vegetation plots along HIP transects were in habitats with over 33 
percent nonnative, invasive plant cover.
    Menke and Kaye (2006b) evaluated the association between measures 
of habitat quality measured by HIP and abundance of L. papilliferum. 
For the one year for which data were available (2004), they report that 
L. papilliferum abundance was not significantly correlated with soil 
crust cover or weedy species cover in slickspots, and that the 
proportion of flowering plants had a positive correlation with soil 
crust cover, but was not significantly correlated with livestock print 
cover or weedy species cover (Menke and Kaye 2006b, p. 15). In their 
overall evaluation of habitat condition, they report that total 
vascular plant cover, species richness, and species diversity had 
declined between 1998 and 2004, and suggest that past fires have been a 
factor in degrading slickspot condition (Menke and Kaye 2006b, p. 19). 
Several features of slickspots, including soil crust cover and weedy 
species cover, were consistently more degraded in burned areas. 
Although slickspots in burned areas had more dense weedy annual species 
cover (Menke and Kaye 2006b, p. 19), Menke and Kaye state that 
``Competition from weedy annual species (which may be promoted by 
fire), does not appear to influence abundance of L. papilliferum plants 
in a given year, but may influence reproductive output, other plant 
traits, and other life history stages' (Menke and Kaye 2006b, p. 17). 
Soil crust cover was significantly lower in 2004 transects with 
evidence of livestock grazing, but there was no direct relationship 
between abundance of L. papilliferum and total livestock print cover or 
cover of print penetrating to the slickspot clay layer (Menke and Kaye 
2006b, p. 15).
    Another measure of habitat quality within Lepidium papilliferum's 
range is the EO ranking by the Idaho CDC. The first EO ranks for L. 
papilliferum were assigned in 1993 (Colket et al. 2006, Tables 1-13). 
In 2006, EO specifications and ranking were revised by the Idaho CDC 
(Colket et al. 2006, pp. 15 to 44). Due to the change in methodology, 
it is difficult to draw conclusions about changes in EO rankings over 
time. EO ranks are designed as an assessment of estimated viability or 
probability of persistence and help prioritize

[[Page 1628]]

conservation planning or actions (NatureServe 2002, p. 36). We consider 
EO rankings to be part of the best available data on the species at 
this time.
    Table 1 summarizes the rankings for 85 EOs based on the 2006 
revised methodology. A-ranked EOs have one or more of the following 
conditions that are summarized through a formula: (1) Over 1,000 
detectable above-ground plants; (2) intact native plant communities 
with trace nonnative species cover; (3) slickspots with zero or trace 
nonnative cover or livestock disturbance; (4) zero or few minor 
anthropogenic disturbances; (5) a lack of burning; and (6) a 
surrounding landscape within 0.6 mi (1 km) that is not fragmented by 
agricultural lands, residential or commercial development, introduced 
annual grasslands, or drill seeding projects (Colket et al. 2006, p. 
3). By contrast, D-ranked EOs exist in the most highly degraded 
habitats, with the fewest plants, and with the most degraded 
surrounding landscape (Colket et al. 2006, p. 3).

                                    Table 1.--Number of Element Occurrences in 2006 by CDC Ranking (Percent of Total)
                                                   [Colket et al. 2006, Tables 1 to 13 and Appendix C]
--------------------------------------------------------------------------------------------------------------------------------------------------------
                 A                        B            BC           C          pC \1\         D          pD \1\       E \2\          F          Total
--------------------------------------------------------------------------------------------------------------------------------------------------------
0..................................     15 (18)        1 (1)      26 (31)        4 (5)      19 (22)        1 (1)      10 (12)       9 (11)           85
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Probable ranks assigned when incomplete information available.
\2\ Not enough habitat information available to make a ranking.

    Of the 66 EOs with B through D rankings (13,123 ac (5,310 ha)), 51 
occur on the Snake River Plain (10,804 ac (4,372 ha)), and 15 on the 
Owyhee Plateau (2,318 ac (938 ha)). Of these 66 middle-ranked EOs, 50 
are ranked as a C or D (averaging fewer than 399 plants, partial to 
nonexistent native plant communities that are partially to 
predominately burned, and partially to predominantly fragmented 
landscapes). The 40 EOs on the Snake River Plain cover 3,170 ac (1,283 
ha), and the 10 EOs on the Owyhee Plateau cover 73 ac (30 ha).
    Habitat data (HII, HIP) have been collected annually for 
approximately one-half of the extant EOs since 1998. Given that 
monitoring methodologies and the specifications for determining EO rank 
changed in 2004/2005, and not every EO is monitored annually, it is not 
possible to draw definitive conclusions about the change in habitat 
quality over time. It is possible, however, to gain an understanding of 
the current condition of habitat quality from the available data. Based 
on the most recent EO ranks, at least 75 percent (n = 49) were ranked 
as C, D, or F, indicating that most EOs occurred in partially or 
predominantly fragmented landscapes with partial to nonexistent native 
plant communities. As discussed below we don't have any data that 
correlate L. papilliferum population numbers with effects to habitat.

Previous Federal Actions

    For a description of Federal actions concerning Lepidium 
papilliferum that occurred prior to January 22, 2004, please refer to 
the document to withdraw our July 15, 2002, proposal published in the 
Federal Register on January 22, 2004 (69 FR 3094).
    On January 22, 2004, we published a document withdrawing our 
proposed rule to list Lepidium papilliferum as endangered (69 FR 3094). 
That action was based on our conclusion that there was ``a lack of 
strong evidence of a negative population trend, and the formalized 
conservation plans (e.g., the CCA and INRMPs) had sufficient certainty 
that they would be implemented and effective such that the risk to the 
species was reduced to a level below the statutory definition of 
endangered or threatened.''
    On April 5, 2004, Western Watersheds Project filed a lawsuit 
challenging our decision to withdraw the proposed rule to list Lepidium 
papilliferum as threatened or endangered (Western Watersheds Project v. 
Jeffery Foss, et al., Case No. CV 04-168-S-EJL). On August 19, 2005, 
the U.S. District Court for the District of Idaho reversed the decision 
to withdraw the proposed rule, with directions that the case be 
remanded to the Secretary of the Department of Interior for 
reconsideration of ``whether a proposed rule listing the slickspot 
peppergrass as either threatened or endangered should be adopted.''
    After issuance of the District Court's remand order, we notified 
Federal, State and local agencies, county governments, elected 
officials, and other interested parties of the Court's decision in a 
letter dated October 13, 2005. We requested new scientific data and 
comments about Lepidium papilliferum. We also stated that scientific 
data received from the public would be included in an updated ``Draft 
Best Available Biological Information for Slickspot Peppergrass 
(Lepidium papilliferum)'' (BAI) document. In response to our request, 
we received a total of 13 comment letters. The updated BAI combined all 
existing and new information about the species and its habitat, and we 
utilized it in making this final listing determination.
    On February 27, 2006, we opened a 30-day public comment and peer 
review period, through an electronic process referred to as VOCUS, for 
our comprehensive document entitled ``Draft Best Available Biological 
Information for Slickspot Peppergrass (Lepidium papilliferum)'' (USFWS 
2006f). Following public and peer review, we used new data and 
technical corrections, along with existing data, for our analysis 
described below as the best available scientific and commercial data.
    After an order by the district Court on October 4, 2006, which 
requires ``a final listing determination on the slickspot peppergrass 
by January 4, 2007,'' we opened a 22-day public comment period that 
closed on November 13, 2006 (71 FR 62078). A variety of documents were 
posted on the FWS Web site for public comment, including peer review 
comments on the draft BAI and results of the expert panel.

Summary of Comments and Responses

    We received a total of 13 comment letters in response to our 
October 13, 2005, request for additional information to assist with the 
listing determination for Lepidium papilliferum; 17 public comment 
letters and 19 peer review responses on the Draft BAI released on 
February 27, 2006; and 20 public comment letters in response to our 
October 23, 2006, reopening of the public comment period. The majority 
of comments were specific to the draft BAI and associated data as well 
as issues surrounding the 2003 CCA developed to conserve L. 
papilliferum. Comments that were substantive or that provided new 
information were incorporated into the final determination where 
appropriate, or are addressed below. We consolidated the comments into 
categories by issue.

[[Page 1629]]

    Issue 1: Several commenters provided new data and information 
regarding the biology, ecology, life history, genetics, and factors 
affecting Lepidium papilliferum, and requested that it be incorporated 
into the body of existing knowledge concerning the species and 
considered by us in making any future management determinations.
    Our response: In making this final listing determination, we have 
considered scientific and commercial data contained in over 75 
technical reports, published journal articles, and other general 
literature documents, including nearly 30 reports received since the 
January 23, 2004. The body of available information specific to this 
species has greatly expanded since 2004, with new information regarding 
species locations, known condition of its habitat, slickspot soil 
characteristics and disturbance, Lepidium papilliferum's pollinators, 
seed viability and germination, ongoing conservation efforts, genetics, 
and factors affecting the species. This information was contained in 
various State agency reports (Colket 2005a; Colket 2006; Colket et al. 
2006; IDARNG 2005; State of Idaho et al. 2006) and other scientific 
reports and peer reviewed articles (Menke and Kaye 2006a, b; Meyer and 
Allen 2005; Meyer et al. 2005; Meyer et al. 2006; Palazzo et al. 2005; 
Robertson 2003a; Robertson and Klemesh 2003; Robertson and Ulappa 2004; 
Robertson et al. 2005; Stillman et al. 2005). Additionally, we reviewed 
and considered data from ongoing L. papilliferum conservation efforts 
(Binder 2006; Boise Airport 2003; Hoffman 2005; IDARNG 2005; State of 
Idaho et al. 2006; U.S. Air Force 2004). Further research and continued 
monitoring would provide a more thorough understanding of the species; 
however, we have a legal obligation to make a final listing 
determination based on the best available scientific and commercial 
data.
    Issue 2: Some commenters stated that an urgent need to list 
Lepidium papilliferum exists due to ongoing and current threats. One 
commenter suggested that there is evidence for widespread and rapid 
population decline. Another commenter stated that the species is at 
such risk of extinction that it should be listed to ensure that the BLM 
and other Federal land management agencies implement management actions 
that result in substantive conservation. Other commenters stated that 
existing regulations are insufficient in providing for the long-term 
persistence of the species. Conversely, some commenters stated that 
existing regulatory mechanisms, primarily through the CCA and its 
associated conservation measures, are sufficient or more than 
sufficient to preclude the need to list L. papilliferum under the Act.
    Our response: The Act requires us to make listing decisions based 
solely on the best scientific and commercial data available at the time 
the decision is made (section 4(b)(1)(A) of the Act). We thoroughly 
reviewed all available scientific and commercial data for Lepidium 
papilliferum in preparing this final determination. We reviewed 
historical and recent publications, and unpublished reports concerning 
L. papilliferum and the sagebrush-steppe habitat of southwestern Idaho. 
From this information, we produced the document ``Draft Best Available 
Biological Information for Slickspot Peppergrass (Lepidium 
papilliferum)'' (BAI); we solicited public comment and peer review on 
the BAI in February 2006. We also convened a panel of seven scientific 
experts to review the scientific information available to us pertaining 
to L. papilliferum. Additionally, we reopened the public comment period 
on the proposed rule in October 2006 (71 FR 62078) to solicit 
additional review and comment on new data that we have considered in 
this final determination.
    We followed our Policy on Information Standards Under the 
Endangered Species Act, published in the Federal Register on July 1, 
1994 (59 FR 34272), and our associated Information Quality Guidelines 
in preparing this final determination. Our evaluation of the 
significance of these numerous ongoing threats across the range of 
Lepidium papilliferum is presented in the Summary of Factors Affecting 
the Species section of this final determination. This analysis includes 
the adequacy of existing regulatory mechanisms, including public land 
management practices. During the listing process, we provided 6 public 
comment periods that were open for a total of 262 days, and held 2 
public hearings. We received new information since the proposed rule 
specific to L. papilliferum that ranged from additional Idaho CDC 
survey data to slickspot soils information. While the body of available 
information specific to this species is limited, our legal obligation 
is to make a final listing determination based on the best available 
data.
    Issue 3: Several comments regarded the effectiveness of the CCA 
(first approved in 2003 and subsequently revised in 2006) in conserving 
Lepidium papilliferum. Some commenters stated that the voluntary 
commitment of non-governmental cooperators developed during the CCA 
process is equal to or better for conservation of L. papilliferum than 
mandated actions that would be associated with listing the species. One 
commenter suggested that the commitment to better livestock grazing 
management by the L. papilliferum Conservation Committee and permittees 
continues, and is still strong after 2 years of implementation, and 
that the follow-through on implementing CCA conservation measures, such 
as responding to grazing triggers and off-highway vehicle (OHV) events 
during 2005, was good. The State of Idaho reported that, of the 203 
conservation measures identified in the CCA, 193 were accomplished in 
either 2004 or 2005, and 7 measures were not implemented due to 
wildfire or ongoing litigation. One commenter stated that the inclusion 
of an adaptive management process within the CCA will ensure that the 
identified conservation measures, if initially ineffective, would 
become effective well before the probable extinction of L. papilliferum 
given existing threats. The U.S. Air Force provided comments on our 
October 23, 2006 draft description and analysis of conservation 
measures (71 FR 62078). The U.S. Air Force believed that several more 
conservation measures have been implemented and are effective in 
conserving L. papilliferum at the Juniper Butte Range than what we had 
determined.
    Conversely, some comments suggested that there is little certainty 
that implementation of Lepidium papilliferum conservation measures 
identified in the CCA will occur. One commenter stated that the 
adaptive management approach used in the CCA provides no certainty of 
protection for L. papilliferum. Another commenter suggested that any 
cooperator can drop out of the CCA at any time without repercussion. 
Another comment asserted that the adaptive management approach as 
currently described in the CCA allows for a one-time disturbance event 
that could result in irreversible harm to L. papilliferum habitat. 
Comments indicated that the CCA provides vast opportunity for a one-
time livestock penetrating trampling event to occur, and is therefore 
insufficient. Other comments suggested that the CCA does not protect L. 
papilliferum and its habitat from soil disturbance, and did not include 
active restoration measures for the vast majority of the species' 
habitats. Commenters stated that, due to the downward trend in L. 
papilliferum abundance, reintroduction of the species should be 
considered. One commenter stated that management

[[Page 1630]]

under an Instruction Memorandum (IM) is uncertain, and that because the 
IM is not a legal requirement, interpretation will be inconsistent 
among field staff.
    Our response: We support utilizing a collaborative conservation 
approach to address factors affecting species being considered for 
listing under the Act. Prior to July 18, 2003, we worked with various 
agencies and individuals to assess the status of Lepidium papilliferum, 
and also to identify and implement conservation actions. Since February 
2000, we have been an active technical advisor in an interagency group 
of biologists and stakeholders to share data and coordinate 
conservation actions for L. papilliferum.
    Using our Policy for Evaluation of Conservation Efforts When Making 
Listing Decisions (PECE) (68 FR 15100), we reviewed the conservation 
measures in five plans, or conservation strategies, for L. 
papilliferum: (1) The Candidate Conservation Agreement for Slickspot 
Peppergrass (CCA), which was initially approved in 2003 and revised in 
2006; (2) the Idaho Army National Guard Integrated Natural Resource 
Management Plan for Gowen Field/Orchard Training Area; (3) the U.S. Air 
Force Integrated Natural Resource Management Plan for Mountain Home Air 
Force Base, which was modified in 2004 and contains more measures that 
promote the conservation of L. papilliferum than the 2000 version; (4) 
the Conservation Agreement (Hull's Gulch 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 
Lepidium papilliferum (slickspot peppergrass), which was in place until 
it expired on October 22, 2006, and (5) the Conservation Agreement for 
slickspot peppergrass (Lepidium papilliferum) at the Boise Airport, Ada 
County, Idaho. These five agreements and plans include a wide array of 
conservation measures to address the need to maintain and enhance 
slickspot peppergrass, and to potentially avoid or reduce adverse 
effects that might occur in relation to various types of activities. We 
recognize that many of the conservation efforts identified in the plans 
are having conservation benefits for the species, particularly as they 
relate to limiting the effects of wildfire and livestock use. We 
believe conservation efforts are important for this species because, 
while we do not have sufficient information to determine that potential 
threats are having a population level impact on the species, further 
research is necessary. To the extent that there are effects from 
activities, these conservation efforts should offset them.
    We evaluated conservation efforts within each plan under PECE (60 
FR 15100). PECE is relevant in situations where it is necessary to 
determine whether individual conservation efforts that have not been 
implemented, or that have been implemented but have not yet 
demonstrated whether they are effective, are sufficiently certain to be 
implemented and effective so as to have contributed to the elimination 
or adequate reduction of one or more threats to the species identified 
through our threats analysis conducted pursuant to section 4(a)(1) of 
the Act. In this case, the efforts that met the standard in PECE for 
sufficient certainty of implementation and effectiveness were not used 
as a basis for our conclusion, because our analysis did not show that 
the species met the definition of threatened or endangered. However, 
this does not mean that conservation efforts which have yet to be 
implemented, or which have yet to be demonstrated to be effective, are 
unimportant. In fact we strongly encourage continued implementation of 
all on-going and planned conservation efforts, as they can contribute 
to maintaining or improving the status of L. papilliferum.
    Issue 4: 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 suggested there have been no comprehensive 
systematic surveys for L. papilliferum, and therefore, we do not fully 
understand the distribution or status of the species. Numerous 
commenters stated that monitoring protocols and methods used to gather 
data regarding L. papilliferum trends and distribution were biased 
toward documenting declines, were insufficient, or were poorly timed, 
and therefore conclusions are poor. Several commenters stated that 
there is no clear relationship between L. papilliferum trends and 
threat factors affecting the species. Some commenters 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. One commenter thought the trend from 2004 to 2005 was 
positive or stable due to implementation of the CCA, a wet spring, and 
a minimal wildfire season. Another commenter identified that the number 
of extant EOs have increased from 45 in 1998 to 85 in 2006, and there 
has been only 1 EO that has been extirpated since 1955. Several 
commenters cited information relating L. papilliferum annual abundance 
to precipitation, while other commenters disputed the claim that annual 
abundance is related to precipitation. Several commenters stated that 
the number of element occurrences has increased from 1998 (45 extant 
EOs) to 2006 (85 extant EOs).
    Several commenters thought that the soil type (slickspots) used by 
Lepidium papilliferum is a limited resource that is not reforming, 
because the processes that originally created it no longer occur. 
Slickspots being modified, altered, or developed are lost to the 
ecosystem forever.
    Our response: In this determination, we have reviewed and 
considered scientific and commercial data contained in over 75 
technical reports, published journal articles, and other documents, 
including nearly 30 reports received since January 22, 2004. 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 also acknowledge that uncertainties exist.
    While a systematic survey, utilizing similar techniques, has not 
been conducted for Lepidium papilliferum range-wide, at least 30 
separate survey efforts for L. papilliferum have occurred (Baczkowski 
2006; USFWS 2006d). Some of these surveys were within the known range 
of L. papilliferum habitat, and others were outside of the known 
distribution, for example, in the State of Oregon, in the Saylor Creek 
area between the Snake River Plain and the Owyhee Plateau, and the City 
of Hagerman. In 2003, for example, 2,350 acres were surveyed in the 
Saylor Creek area between the Snake River Plain metapopulations and the 
Owyhee Plateau metapopulations. During these surveys, 1,727 slickspots 
were documented, but no L. papilliferum individuals were found (U.S. 
Air Force 2003, p. 16). 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. Recent discoveries of new occupied slickspot sites 
and new EOs since 1998 have not added substantially to our knowledge of 
where the species exists. For example, an inventory survey at the OTA 
in 2005 found 365 new slickspots with L. papilliferum all within the 
range of known habitat on the OTA (URS

[[Page 1631]]

Corporation 2005, p. 6). Since 2003, 16 new EOs on approximately 50 ac 
(28 ha) (0.4 percent of the total acreage) have been documented, all 
within 3 mi (4.8 km) of previously existing EOs (Colket et al. 2006, 
Tables 1 to 14). Although there has been only one documented 
extirpation since 1955, up to 9 small and isolated EOs had no plants 
detected during one or more recent monitoring surveys.
    Numerous monitoring efforts have been conducted for Lepidium 
papilliferum, including population trend monitoring transects at the 
OTA (IDARNG 2005) completed since 1991, demographic monitoring at the 
OTA from 1993 to 1996 (Meyer et al. 2005), Habitat Integrity Index 
(HII) monitoring done by the Idaho CDC at L. papilliferum EOs range-
wide conducted from 1998 to 2002 (Mancuso and Moseley 1998; Mancuso et 
al. 1998; Mancuso 2000; Mancuso 2001; Mancuso 2002), Habitat Integrity 
Population (HIP) monitoring built on HII monitoring at L. papilliferum 
EOs range-wide conducted by the Idaho CDC in 2004 and 2005 (Colket 
2005a, Colket 2005b), and monitoring done at the Juniper Butte Range in 
2003 and 2005 (U.S. Air Force 2003). HIP monitoring, the most extensive 
range-wide effort to date, was developed by the Idaho CDC in 
conjunction with the L. papilliferum Technical Team to statistically 
analyze and detect trends in L. papilliferum and its habitat (the 
technical team includes IDARNG, BLM, Air Force, the Service, Idaho 
Department of Agriculture, and other interested parties) (Colket 2005a, 
p. 3). Both the HII and HIP monitoring, because of the difficulties 
associated with tracking numbers of L. papilliferum individuals across 
years, utilize habitat information as a metric of L. papilliferum 
health (Mancuso et al. 1998, pp. 1 to 7).
    Because of the fluctuations in Lepidium papilliferum numbers 
associated with precipitation (Meyer et al. 2005, pp. 4, 12, 15; 
Palazzo et al. 2005, p. 9; Menke and Kaye 2006b, p. 10), determining 
trends requires long-term monitoring data sets. Two long-term 
monitoring data sets in which we see a downward trend in recent years 
in numbers of individuals that do not mimic precipitation are the 
population trend monitoring transect data and special use plot data at 
the OTA. In contrast, an analysis by Palazzo et al. (2005, p. 9) for 
all 4 years of HII data found a relationship (p-value less than 0.01) 
between February to June precipitation and numbers of L. papilliferum. 
In their analysis of range-wide HII and HIP data collected from 1998-
2002 and 2004 (no data was collected in 2003), Menke and Kaye (2006b, 
p. 10) further refined this relationship and found a strong positive 
relationship between precipitation from March through May and L. 
papilliferum abundance. In contrast to the monitoring data from OTA, 
the range-wide data shows that L. papilliferum continues to track 
consistently with precipitation throughout all years of the data set 
(Menke and Kaye 2006b, p. 10 and Figs. 1, 2). We consider this range-
wide data to be the best available at this time.
    The conditions that allowed for the formation of slickspots in 
southwestern Idaho are thought to have occurred during a wetter 
Pleistocene climate (Nettleton and Petersen 1983, p. 191; Seronko 
2006). Under natural conditions, several hundred years may be necessary 
to alter or lose slickspots, generally through climate change or severe 
natural erosion (Seronko 2006). Meyer and Allen (2005, p. 9) suggest 
that if sufficient time passes following the disturbance of slickspot 
soil layers, it is possible that slickspots can reform similar to their 
pre-disturbance configuration.
    Issue 5: Numerous commenters provided information or opinions 
regarding how various threats may or may not affect Lepidium 
papilliferum, its habitat, and its possible probability of extirpation. 
Threats specifically mentioned included residential, commercial, and 
agricultural development; military training; OHV use; nonnative, 
invasive plant species; wildfire; wildfire rehabilitation methods 
(including drill seeding and invasive, nonnative plant seedings); 
fragmentation; soil disturbance; herbicide spraying; wildlife grazing; 
herbivory; and agricultural pesticides (e.g., insecticide for 
grasshoppers or Mormon crickets) affecting L. papilliferum pollinators. 
One commenter suggested that the decreased quality of sagebrush 
grassland (steppe) habitat is the primary problem with the apparent 
decline of L. papilliferum.
    Our response: Our evaluation of the significance of the various 
threats across the range of Lepidium papilliferum is discussed in the 
Summary of Factors Affecting the Species section of this final 
determination. We analyzed the adequacy of existing regulatory 
mechanisms, including the effectiveness of ongoing, recently 
implemented, and proposed conservation efforts that attempt to conserve 
L. papilliferum in three conservation agreements, and two INRMPs from 
the IDARNG and the U.S. Air Force. The primary factors impacting L. 
papilliferum and its surrounding habitat include habitat degradation 
and modification of the sagebrush-steppe ecosystem from the current 
wildfire regime (i.e., increasing frequency, size, and duration of 
wildfires), invasion of nonnative weed species (e.g., cheatgrass), 
effects of livestock use (e.g., trampling and disruption of soils), and 
habitat loss due to agricultural and urban development. Less important 
factors that may affect the species include effects from rangeland 
revegetation projects, wildfire management practices, recreation, and 
military use. Herbivory is reported as sparse or at low levels, and is 
mainly by insects. Herbivory impacts to L. papilliferum from native 
ungulates such as elk, deer, and antelope have not been observed. 
However, pronghorn antelope tracks and droppings (U.S. Air Force 2003, 
p. 14), and elk tracks and droppings (State of Idaho et al. 2006, 
Appendix A) have been infrequently documented in slickspots that 
support L. papilliferum. Herbicide spraying was not considered by the 
Expert Panel to be an important threat to L. papilliferum, and is not 
discussed in this listing determination. While the decreased quality of 
sagebrush-steppe and the development and implementation of successful 
habitat restoration may impact the species, we have found no 
correlation to date between the existence of these threats and 
population numbers.
    Issue 6: Several comments referred to the effects of livestock use 
on Lepidium papilliferum and its habitat. They suggested that livestock 
use (past, current, or future) adversely affects L. papilliferum by 
trampling and uprooting individual plants, transporting nonnative 
invasive seeds, disturbing slickspot habitat soil crusts, burying L. 
papilliferum seeds to a soil depth at which germination cannot occur, 
accelerating erosion of slickspots, compacting soils, and changing 
slickspot soil chemistry through the deposition of manure.
    Conversely, several commenters suggested that livestock use has 
minimal effects and can even provide beneficial effects to Lepidium 
papilliferum and its habitat. One commenter suggested that only three 
documented examples exist in which livestock use has been implicated as 
the primary factor in either a reduction or elimination of L. 
papilliferum from a given area. In each case, the incident was isolated 
and occurred prior to implementation of the CCA. Several commenters 
suggested that L. papilliferum co-evolved with historical livestock use 
and wild ungulate grazing pressure; therefore the impact of existing 
livestock use is as likely to be

[[Page 1632]]

beneficial as it is to be adverse, although effects generally remain 
unknown. Commenters suggested that potential benefits to L. 
papilliferum from livestock use include reduced frequency, intensity, 
and magnitude of wildfire; reduced nonnative invasive annual grasses; 
and improved germination of L. papilliferum seeds as a result of 
abrasion and reduced physical resistance of the surface soil crust. One 
commenter suggested that without authorized livestock grazing permits 
on Federal lands, some conservation benefits would not occur, including 
weed control, wildfire suppression, habitat rehabilitation, and a ready 
source of information regarding the land upon which ranchers run their 
livestock. Other commenters suggested that insufficient information 
exists, so we cannot draw conclusions regarding the effects of 
livestock use on L. papilliferum and its habitat.
    Our response: The most visible effect on Lepidium papilliferum and 
its slickspot habitat from livestock use is trampling impacts. 
Penetrating trampling is defined as livestock trampling of water-
saturated slickspot soils that break through the restrictive soil layer 
(see Ecology and Habitat section above). Penetrating livestock 
trampling can affect the fragile soil layers of slickspots (Meyer et 
al. 2005, pp. 21, 22; Seronko 2004, pp. 1, 2), especially when it 
occurs during wet periods when slickspots are most vulnerable to 
disturbance. Penetrating trampling also potentially affects the seed 
bank for L. papilliferum by pushing the seeds below their ability to 
germinate (i.e., below 1.5 in (3 cm)) (Meyer et al. in press, pp. 3, 
24, 25). Livestock use at an appropriate level, and during dry 
conditions, may reduce the spread of nonnative annual grasses at some 
L. papilliferum sites. However, using livestock to control nonnative 
annual grasses would need to occur during early spring when the grasses 
are growing strongly, and spring is when slickspots are most likely to 
be wet and most susceptible to damage. Responsive management, involving 
quickly removing livestock during rain events and moving them regularly 
to prevent soil disturbance, would be difficult over large areas.
    Livestock use has been documented (Colket et al. 2006, Appendix C) 
within 62 of the 75 Lepidium papilliferum EOs for which habitat 
information has been collected (49 of 60 on the Snake River Plain and 
13 of 15 on the Owyhee Plateau). Penetrating hoof prints have been 
documented within 21 EOs on the Snake River Plain, and 9 on the Owyhee 
Plateau (Colket et al. 2006, Appendix C).
    Data limitations have made it difficult to establish impact (or 
effect) thresholds from livestock management activities for Lepidium 
papilliferum. Based on a single year of HIP data (2004), there was no 
correlation between L. papilliferum abundance in the short-term and 
total livestock print cover or cover of prints penetrating to the 
slickspot clay layer (Menke and Kaye 2006b, p. 15). The HIP data are 
observational in nature; controlled experiments are needed to more 
accurately assess the effects of livestock on L. papilliferum and its 
habitat. At this time we have no data that long-term declines in 
abundance will arise from livestock grazing. Adaptive management 
techniques for areas occupied by L. papilliferum and affected by 
livestock use could result in new information from ongoing and proposed 
livestock use studies and monitoring conservation efforts for the 
species. We anticipate that additional information regarding L. 
papilliferum and livestock use, from research currently underway by the 
U.S. Air Force and University of Idaho will be available for use in 
species conservation.
    A more complete discussion on the effects of livestock use on 
Lepidium papilliferum and its habitat is found in the Summary of 
Factors Affecting the Species section.
    Issue 7: One commenter suggested that wildfire historically (prior 
to European influence) occurred on a 60- to 100-year frequency and 
resulted in small burned areas where wind erosion could scour 
slickspots, maintaining the thin silt layer on the slickspot and the 
mini-playa as a depression. Wind scour likely occurred, since the only 
species growing on the slickspot was Lepidium papilliferum. With exotic 
species currently occupying slickspots, wind erosion may not be 
effectively scouring them, and in fact, deposition may be occurring. 
One commenter suggested that historical wildfire intervals in Wyoming 
big sagebrush communities were much longer, and some areas rarely, if 
ever, burned.
    Conversely, one commenter stated that while an abundance of 
information exists regarding wildfire in Lepidium papilliferum habitat, 
no long-term monitoring data confirmed the significance of its effect 
on L. papilliferum.
    Our response: As previously stated in the July 15, 2002, proposed 
rule (67 FR 46441) and January 22, 2004, document to withdraw the 
proposed rule (69 FR 3094), wildfire affects Lepidium papilliferum EOs 
throughout the species' range. Where habitat information is known, 42 
of 60 EOs on the Snake River Plain and 6 of 15 on the Owyhee Plateau 
have been at least partially burned; 57 EOs on the Snake River Plain 
and 12 on the Owyhee Plateau have adjacent landscapes that are at least 
partially burned (Colket et al. 2006, Appendix C).
    Current research indicates wildfire frequency in the sagebrush-
steppe ecosystem throughout the range of Lepidium papilliferum has 
increased, from a historical average of once every 60 to 110 years to 
once every 5 years at many sites, due to the invasion of nonnative 
annuals such as cheatgrass that became common on the Snake River Plain 
rangelands in the 1950's (Wright and Bailey 1982, p. 158; Billings 
1990, pp. 307 to 308; Whisenant 1990, p. 4; USGS 1999, pp. 1 to 9; West 
and Young 2000, p. 262). Wildfires in cheatgrass tend to be larger, 
burn more uniformly, and leave fewer patches of unburned vegetation, 
all of which influence the post-fire recovery of native sagebrush-
steppe vegetation (Whisenant 1990, p. 4). The result of this altered 
wildfire regime has been the conversion of vast areas of the former 
sagebrush-steppe ecosystem into nonnative annual grasslands (USGS 1999, 
pp. 1 to 9). Frequent wildfires can also promote soil erosion and 
sedimentation (Bunting et al. 2003, p. 82) in arid environments such as 
the sagebrush-steppe ecosystem. Increased sedimentation can result in a 
silt layer that is too thick for optimal L. papilliferum seed 
germination (Meyer and Allen 2005, pp. 6 to 7), and that allows weedy 
species to invade slickspots. See the Summary of Factors Affecting the 
Species section for a more complete discussion.
    Following wildfire events, the use of nonnative forage grass 
species (such as crested wheatgrass and Russian wildrye (Elymus 
junceus)) for rehabilitation can result in successful establishment of 
perennial plants, ultimately reducing and diminishing the impacts of 
cheatgrass and its accelerated wildfire frequency. The use of nonnative 
species that closely mimic the biology and ecological function of 
species native to the area may be a necessary first step in restoring a 
site following wildfire if native seed cannot be used due to limited 
availability or prohibitive cost.
    Of the known Lepidium papilliferum occurrences, 14 (19 percent) are 
located within areas where wildfire rehabilitation projects and crested 
wheatgrass seedings have occurred (Colket et al. 2006, Appendix C). 
Although L. papilliferum still occurs in these areas, most support 
lower numbers of plants (Mancuso and

[[Page 1633]]

Moseley 1998). See ``Factor A'' in the Summary of Factors Affecting the 
Species section below for a more detailed discussion.
    In a review of available information, the Expert Panel considered 
the current wildfire regime the most important factor affecting 
Lepidium papilliferum and its remaining habitat.
    Issue 8: One commenter expressed concerns regarding the U.S. Air 
Force's development of the Juniper Butte Range (beginning in 1998) on 
the Owyhee Plateau where Lepidium papilliferum and its habitat occur. 
Development and use of this training range, along with resulting road 
construction, human presence, and proposed use of aerial flares/white 
phosphorus munitions during training exercises, has increased the risk 
of wildfire within a substantial portion of L. papilliferum's range.
    Our response: Currently, the impact of military training activities 
does not represent a principal threat to Lepidium papilliferum. Both 
the IDARNG and U.S. Air Force are implementing conservation efforts 
that potentially avoid or reduce adverse effects of military training 
on the species and its habitat. Threats from military activities are 
localized and have little significance across the range of the species.
    Military activities within the range of Lepidium papilliferum 
include ordnance use, facility development, and transportation, all of 
which create an increased risk of wildfire and nonnative plant 
invasions. Military training occurs on the Snake River Plain at the 
OTA, on all or portions of seven EOs, and on the Owyhee Plateau at the 
Juniper Butte Range on a portion of one EO (sub EO 704). The U.S. Air 
Force intends to use 300 ac (121 ha) of the 11,070-acre Juniper Butte 
Range as the actual bombing impact area (U.S. Air Force 2000). It 
anticipates that a small amount of ordnance will be dropped outside the 
bombing impact area, but the potential impact to L. papilliferum would 
likely be minimal.
    The Integrated Natural Resource Management Plan (INRMP) developed 
for the Juniper Butte Range provides management directions that 
ameliorate many of the threats from military training exercises. Range-
wide, the most intact Lepidium papilliferum habitat occurs at the OTA, 
where similar conservation efforts have been implemented for 14 years 
(Colket et al. 2006, pp. 22 to 23; Meyer 2005, p. 1). The IDARNG has 
implemented a variety of actions to meet the conservation needs of L. 
papilliferum, while still providing for military training activities. 
These actions include wildfire suppression efforts, and restricting 
ground-operated military training to areas where the plants are not 
found.
    Issue 9: Some commenters asserted the taxonomic status of Lepidium 
papilliferum is problematic and warrants further evaluation. For 
example, one commenter suggested that our failure to complete a genetic 
study of Lepidium montanum seriously flaws any discussion assessing L. 
papilliferum as a species on its own. A few commenters suggested that 
if L. papilliferum is a subspecies or variety it is not eligible for 
protection under the Act.
    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 review of taxa in the mustard family 
(Brassicaceae), Rollins (1993) maintained the species based on 
differences in the physical features between L. papilliferum and L. 
montanum such as: (1) L. papilliferum has trichomes (hair-like 
structures) occurring on the filaments of stamens (part of flower that 
produces pollen), and L. montanum does not; (2) all the leaves on L. 
papilliferum are pinnately divided, and L. montanum has some leaves 
that are not divided; (3) the shape of the silicle [silique] (seed 
capsule) 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. Meyer et al. (2005, p. 17) described a life 
history contrast when compared to L. montanum regarding seed dormancy 
and the seed bank. L. papilliferum seeds can remain dormant (and 
viable) and persist in the seed bank for about 12 years, whereas L. 
montanum has largely non-dormant seeds (Meyer et al. 2005, p. 17). Most 
recently, L. papilliferum has been accepted as a distinct species by 
Intermountain Flora, a recognized regional text (Holmgren et al. 2005, 
p. 259); the U.S. Department of Agriculture's ``PLANTS Database'' 
(USDANRCS 2006); and the Biota of North America Project, the recognized 
taxonomic reference for the United States (ITIS 2006).
    The preliminary results of two studies on the genetics of Lepidium 
papilliferum recently became available. The first, based on a 
relatively small sample size and more limited methodology, found that 
L. papilliferum forms a distinct monophyletic group that is most 
closely related to L. fremontii (Smith 2006, pp. 5 to 7 and Fig. 1). 
The second, utilizing larger sample sizes and additionally applying the 
methodology of AFLP (amplified fragment length polymorphisms, 
recognized for greater resolution or discriminatory power in detecting 
genetic differentiation) (Mueller and Wolfenbarger 1999, pp. 389 to 
393; Savelkoul et al. 1999, p. 3085)), found that L. papilliferum forms 
a distinct monophyletic group or subgroup, and indicates that it is 
most closely related to L. montanum var. montanum (Larson et al. 2006, 
p. 13, 15, and Fig. 4). These genetic studies are consistent with the 
interpretation that L. papilliferum is either a variety or subspecies 
of L. montanum, or that it is a full and distinct species that has 
recently diverged from L. montanum. Plant species and subspecies (or 
varieties) are eligible for protection under the Act.
    Issue 10: One commenter stated that very little scientific research 
has been conducted on Lepidium papilliferum, and subsequently very 
little peer-reviewed literature is available for the species. Most of 
the information we have is based on technical reports and personal 
communications.
    Our response: The Act requires us to make listing decisions based 
on the best scientific and commercial data available at the time the 
decision is made (section 4(b)(1)(A) of the Act). Following the August 
19, 2005, Federal Court decision regarding our January 22, 2004, 
document to withdraw the proposed rule to list Lepidium papilliferum as 
endangered, we sought and received new scientific and commercial data 
pertaining to the species. We incorporated all relevant new information 
into the ``Draft Best Available Information (BAI) for Slickspot 
peppergrass (Lepidium papilliferum)'' document, which was updated from 
the 2003 version. We solicited public comment and peer review on the 
draft BAI document and requested additional scientific data pertaining 
to the species. We followed

[[Page 1634]]

our Information Quality Guidelines in preparing this final 
determination (see Information Quality Act discussion below). We also 
convened a panel of seven scientific experts (see Expert Panel 
discussion below) to review the available data pertaining to L. 
papilliferum prior to making this final determination.

Information Quality Act

    In our review of the status of Lepidium papilliferum, we assembled 
information that addressed the current biological and ecological 
condition of the plant and its habitats. This information included 
reports from private industry, public universities, State and Federal 
resource agencies, published texts on a variety of biological topics, 
and peer-reviewed literature from the primary scientific journals. 
Additionally, we included unpublished scientific and commercial data , 
documents written and included in literature, and personal 
communications. Personal communications were used when they represented 
information that was pertinent and not available through other sources 
such as technical reports or published texts.
    We carefully evaluated each piece of data for its usefulness in the 
review process, and used those that contributed important information 
to the review. State and Federal government documents are generally 
considered to be of high utility, objectivity, and integrity. These 
documents are often subject to public review and comment, and State and 
Federal agencies generally employ the current standards in resource 
survey, monitoring, and analysis methodologies. The peer-reviewed 
scientific literature and scientific textbooks are rigorously reviewed 
and edited at several levels before publication, and represent the 
highest degree of utility, objectivity, and integrity.
    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 our Information Quality Act Guidelines in developing 
this document. 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 the 
draft BAI 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 Lepidium papilliferum, and 
threats affecting the species, were derived from previous petition 
findings, previous Federal Register notices, Idaho's Conservation Data 
Center EO records, and other pertinent references from 1897 (when the 
species was first collected) through 2006.
    The supporting information, administrative finding, and other 
relevant materials can be reviewed in person at the address listed in 
the ADDRESSES section, or copies of information can be made available 
to you (see References Cited at the end of this rule).

Summary of Factors Affecting the Species

    Section 4 of the Act and its implementing regulations (50 CFR part 
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. The five 
listing factors are: (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; and (E) other natural or manmade 
factors affecting its continued existence.

A. The Present or Threatened Destruction, Modification, or Curtailment 
of its Habitat or Range

Current Wildfire Regime
    The invasion of nonnative plant species, particularly annual 
grasses such as cheatgrass and medusahead (Taeniatherum caput-medusae), 
beginning in the early 1900's has increased the amount and continuity 
of fine fuels across the landscape. As cheatgrass became more dominant 
on the rangelands of the Snake River Plain in the 1950's, wildfire 
frequency intervals began to shorten from the historic average of 
between 60 to 110 years to the current frequency intervals of less than 
5 years in many areas on the Snake River Plain where Lepidium 
papilliferum resides (Whisenant 1990, p. 4) and within the sagebrush-
steppe ecosystem as a whole (Wright and Bailey 1982, p. 158; Billings 
1990, pp. 307 to 308; USGS 1999, pp. 1 to 9, West and Young 2000, p. 
262). Wildfires tend to be larger and burn more uniformly when annual 
grasses are present, resulting in fewer patches of unburned vegetation, 
which can affect the post-fire recovery of native sagebrush-steppe 
vegetation (Whisenant 1990, p. 4). This altered wildfire regime has 
contributed to the conversion of vast areas of sagebrush-steppe 
ecosystem into nonnative annual grasslands (USGS 1999, pp. 1 to 9). 
More frequent wildfires also promote soil erosion and sedimentation 
(Bunting et al. 2003, p. 82) in arid environments such as the 
sagebrush-steppe ecosystem. Increased sedimentation can result in a 
silt layer that is too thick for optimal L. papilliferum germination 
(Meyer and Allen 2005, pp. 6 to 7).
    Of the 75 EOs for which habitat information is known, 48 (42 of 60 
on the Snake River Plain and 6 of 15 on the Owyhee Plateau) have been 
at least partially burned, and 69 (57 on the Snake River Plain and 12 
on the Owyhee Plateau) have adjacent landscapes that are at least 
partially burned (Colket et al. 2006, Appendix C). Within the Snake 
River Plain, approximately 448,917 acres (181,670 ha) (28 percent) were 
burned between 1970 and 2003 (calculated from USBLM 2004). Within the 
Owyhee Plateau 60,467 acres (24,470 ha) (47 percent) have burned 
between 1970 and 2003 (calculated from BLM 2004).
    Table 3 shows the evidence of wildfire documented through HIP 
range-wide transect monitoring in 2005. Wildfire evidence can remain on 
the landscape for up to 20 years, and evidence documented in Table 3 
includes both recent and historical fires.

[[Page 1635]]



        Table 3.--Evidence of Wildfire Documented at HIP Transects in 2005 (Colket 2005a, Tables 1 and 2)
----------------------------------------------------------------------------------------------------------------
                                     Number of transects     Number of                Adjacent landscapes within
                                      at least partially     transects      Total       0.31 mi (500 m) of EOs
                                            burned          not burned    transects   burned or partially burned
----------------------------------------------------------------------------------------------------------------
Snake River Plain.................                     26            31           57                          45
Owyhee Plateau....................                     12            10           22                          21
                                   -----------------------------------------------------------------------------
    Total.........................                     38            41           79                          66
----------------------------------------------------------------------------------------------------------------

    In a statistical analysis of HII data between 1998 and 2001, burned 
areas at the beginning of the study had depleted shrub and soil crust 
cover that persisted throughout the monitoring period (Menke and Kaye 
2006a, p. iii). In addition, burned areas had less native plant cover, 
greater nonnative plant cover, increased slickspot perimeter 
compromise, and increased organic debris accumulation (Menke and Kaye 
2006a, p. iii). Similarly, 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). Although the 
proportion of flowering plants was positively correlated with soil 
crust cover, there was no relationship between L. papilliferum plant 
abundance and soil crust cover or weedy species cover in slickspots 
based on the 2004 HIP data (Menke and Kaye 2006b, p. 15). In their 
analysis, Menke and Kaye (2006b, p. 17) concluded that competition from 
weedy annual species does not appear to influence abundance of L. 
papilliferum plants in a given year, although it may influence 
reproductive output or other traits, and that past fire disturbance 
does not appear to significantly alter longer-term trends in plant 
abundance. Past fires have apparently degraded slickspot condition, as 
evidenced by lower soil crust cover and greater exotic species cover 
(Menke and Kaye 2006b, p. 19), however Lepidium papilliferum abundance 
was statistically similar between burned and unburned transects from 
1998 to 2004 (Menke and Kaye 2006b, p. 10), and the proportion of L. 
papilliferum in flower was similar between burned and unburned 
transects in 2004 (Menke and Kaye 2006b, p. 15).
    Past fires appear to have had a lasting negative impact on the 
plant community surrounding slickspots, including increased exotic 
species cover and decreased soil crust cover (Menke and Kaye 2006b, p. 
19). Menke and Kaye (2006b, p. 17) note that the HII and HIP data are 
observational only, and controlled experiments are needed to more 
accurately assess the impacts of factors such as fire and grazing on L. 
papilliferum (Menke and Kaye 2006b, p. 17). At this point, given the 
equivocal nature of the habitat integrity and population monitoring 
data, the effects of an altered sagebrush steppe wildfire regime on L. 
papilliferum need further study. We have no data at this point that 
indicates that fire has a long-term impact on the species abundance; 
the available data show no correlation between fire and L. papilliferum 
population numbers.
    Existing conservation measures designed to reduce the adverse 
effects of wildfire apply to approximately 96 percent of Lepidium 
papilliferum's occupied range. For example, the IDARNG, U.S. Air Force, 
and BLM will continue their rapid response or mutual support agreement 
for wildfire control. BLM has established wildfire suppression goals 
for management areas in the CCA (State of Idaho et al. 2006, Table 5).
    The military is implementing a number of efforts that address 
wildfire suppression that have been shown to be effective in certain 
respects at controlling this threat. However, we are not relying on the 
implementation of conservation measures to make this finding. 
Implemented and effective conservation measures will, however, help to 
counter habitat degradation generally and may help conserve the 
species. Since the late 1980s, the policies of the IDARNG included 
immediate wildfire suppression during military activities to prevent 
damage to intact sagebrush-steppe and Lepidium papilliferum sites 
within the OTA (IDARNG 2004, pp. 65 to 67). Seven occurrences of L. 
papilliferum occur within this area (Colket et al. 2006, pp. 8 to 9). 
Since 2002, the U.S. Air Force has instituted a high-level rapid 
response for wildfire suppression on the Juniper Butte Range (U.S. Air 
Force 2004, pp. 6-45 to 6-47). 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 (e.g., along roads), and using wildfire indices to determine 
wildfire hazard ratings and restricting activities when the rating is 
extreme (U.S. Air Force 2004, pp. 6-45 through 6-47). The BLM and 
IDARNG are continuing their mutual support agreement for wildfire 
suppression in the Snake River Birds of Prey National Conservation Area 
(IDARNG 2004, p. 83).
    On the OTA, the reduction in wildfires within EOs has demonstrated 
that management efforts to suppress wildfire can be effective. The 7 
EOs on the OTA represent nearly 40 percent of the total area occupied 
by Lepidium papilliferum (see Figure 1 above), and aggressive wildfire 
suppression has occurred for over 12 years. The feasibility of 
implementing rapid response wildfire suppression techniques elsewhere 
is complicated by the fact that many of the remaining L. papilliferum 
EOs are in remote areas away from wildfire control facilities. The 
current wildfire regime is interrelated with several other factors that 
may affect L. papilliferum, including the replacement of large areas of 
native vegetation with more flammable nonnative grasses, increased 
sedimentation of slickspots, and habitat fragmentation. While these 
effects may be occurring, the existing data do not correlate them with 
declines in abundance of L. papilliferum.
Invasive Nonnative Species
    The most common nonnative annual grasses known to occur in Lepidium 
papilliferum's habitat include cheatgrass and medusahead. Annual forbs 
most commonly associated with slickspots include clasping pepperweed 
(Lepidium perfoliatum), tumbleweed (also known as Russian thistle), 
tumble mustard (Sisymbrium altissimum) (also known as tall tumble 
mustard), and bur buttercup (Colket 2005a, p. 6). Nonnative plants may 
become established in L. papilliferum habitats by spreading through 
natural dispersal (unseeded) or may be intentionally planted through 
re-vegetation projects (seeded). Invasive nonnative plants can alter 
attributes of ecosystems, including geomorphology, wildfire regime, 
hydrology, microclimate, nutrient cycle, and productivity (Dukes and 
Mooney 2003, pp. 1 to 35). They can also negatively affect native 
plants through

[[Page 1636]]

competitive exclusion, niche displacement, hybridization, and 
competition for pollinators; examples are widespread among taxa and 
ecosystems (D'Antonio and Vitousek 1992, pp. 63 to 87; Olson 1999, p. 
5; Mooney and Cleland 2001, p. 1). All 75 EOs for which habitat 
information is available have nonnative, unseeded plants present 
(Colket et al. 2006a, Appendix C).
    The results from 2004 HIP monitoring revealed that all 71 HIP 
transects monitored within EOs (49 on the Snake River Plain and 22 on 
the Owyhee Plateau) had nonnative, unseeded plant cover. For example, 
within the Snake River Plain (49 transects), 1 had nonnative plant 
cover occurring over 50 percent of the transect, 7 transects had 
nonnative plant cover between 25 and 50 percent of the transect, and 10 
transects had nonnative plant cover between 10 and 25 percent. Two 
transects on the Owyhee Plateau had nonnative plant cover between 10 
and 25 percent (Colket 2005a, pp. 46 to 47).
    In their analysis of Lepidium papilliferum population trends in 
association with plant community trends and habitat quality based on 
HII and HIP monitoring data from 1998-2002 and 2004, Menke and Kaye 
(2006b, p. 12) report that species diversity and species richness of 
the plant community had declined, but that exotic species cover and 
shrub cover had remained the same. Total exotic species cover and 
exotic grass cover was high in burned transects in all years (Menke and 
Kaye 2006b, p. 15). Weedy species cover was higher in burned 
slickspots, but there was no significant correlation between weedy 
species cover and either abundance of L. papilliferum or proportion of 
L. papilliferum in flower (Menke and Kaye 2006b, p. 15). The authors 
note that although competition from weedy annuals does not appear to 
influence the short-term abundance of L. papilliferum, it may be 
influencing other plant traits or life history stages not assessed in 
this study (Menke and Kaye 2006b, p. 17). However, we have no data to 
corroborate that this threat will result in future declines in 
abundance.
    Existing conservation measures designed to reduce the potential 
adverse effects of nonnative, unseeded species apply to approximately 
96 percent of Lepidium papilliferum's occupied range (CCA, U.S. Air 
Force INRMP, IDARNG INRMP). Conservation measures identified within the 
CCA include protecting remnant blocks of native vegetation, prioritized 
weed control measures at L. papilliferum EOs, protective weed control 
techniques, revegetation requirements in disturbed areas, education on 
nonnative species and their spread, vehicle wash points and stations, 
and research support and funding for nonnative species control (State 
of Idaho et al. 2006, pp. 131 to 132).
    The military has a number of ongoing efforts to suppress non-native 
species. The IDARNG requires all military vehicles entering the OTA 
from a distance greater than 50 mi (80.4 km) to be washed at a high-
pressure wash rack facility to prevent weed seed introduction. Noxious 
weeds at small sites are hand-pulled when they are found by IDARNG 
staff, and noxious weed sites on the OTA are reported annually to BLM 
for treatment (IDARNG 2004, p. 67). The U.S. Air Force reduces the 
spread of exotic annual species by reseeding disturbed areas with 
native vegetation to the maximum extent practicable, eradicating 
noxious weeds prior to spread, and requiring cleaning of U.S. Air Force 
vehicles and equipment on a wash rack upon return to base. They avoid 
the use of pesticides within 25 feet of slickspots and use pesticides 
only if wind conditions are favorable (away from the slickspot) to 
prevent the loss of Lepidium papilliferum (U.S. Air Force 2004, pp. R-
4, R-5).
    The OTA has demonstrated that management efforts to suppress 
wildfire, rehabilitating areas with native species, and using wildfire 
rehabilitation activities with minimal ground disturbance can be 
effective in reducing the wildfire threat and reducing rates of spread 
of nonnative unseeded species. Nonnative, unseeded species are 
increasing at the OTA, although not as rapidly as at other areas where 
these conservation efforts are not being implemented or have only been 
implemented for a short period.
    We have no evidence that correlates invasive species presence with 
declines of L. papilliferum or the proportion of L. papilliferum in 
flower (Menke and Kaye 2006b, p. 15).
Livestock Use
    Trampling of Lepidium papilliferum and slickspots can result from 
livestock use. Table 4 documents the extent of livestock use at HIP 
transects. Livestock trampling can affect the soil layers of slickspots 
(Colket 2005a, p. 34; Meyer et al. 2005, pp. 21 and 22; Seronko 2004, 
pp. 1 and 2). Trampling when slickspots are dry can lead to mechanical 
damage to the slickspot soil crust, potentially resulting in invasion 
of nonnative plants into the slickspots and altering the hydrologic 
function of slickspots. Livestock trampling of water-saturated 
slickspot soils that breaks through the restrictive layer, which is 
referred to as penetrating trampling (State of Idaho et al. 2006, p. 
9), has the potential to alter the soil structure and the functionality 
of slickspots (Rengasamy et al. 1984, p. 63; Seronko 2004, pp. 1 and 
2). Penetrating trampling, which occurs when slickspots are wet, also 
has the potential to affect the seed bank for L. papilliferum. Meyer 
and Allen (2005, pp. 6 and 7); seed emergence success decreased with 
increasing depth from a mean of 54 percent at the shallowest plant 
depth of 2 mm to a mean of 5 percent at 30 mm depth.

    Table 4.--Livestock Use Documented at Element Occurrences and HIP
           Transects in 2004 (Colket et al. 2006, Appendix C).
 [Evidence of livestock use does not infer effects throughout a transect
                                 or EO]
------------------------------------------------------------------------
                                                            Evidence of
                                            Evidence of     penetrating
                                            penetrating   trampling (HIP
                                          trampling (EO)    Transects)
------------------------------------------------------------------------
Snake River Plain.......................           21/60           19/49
Owyhee Plateau..........................            9/15           20/22
                                         -------------------------------
    Total...............................           30/75           33/71
------------------------------------------------------------------------


[[Page 1637]]

    In a statistical analysis of HII data from 1998 to 2001, it was 
found that recent livestock use had neutral effects on Lepidium 
papilliferum, slickspot attributes, and plant community attributes 
(Menke and Kaye 2006a, p. iii). Recent livestock use estimated by HIP 
monitoring in the year 2004 resulted in decreased soil crust cover in 
slickspots, decreased vascular plant cover, and decreased plant litter 
cover in the surrounding plant community (Menke and Kaye 2006b, p. 3). 
There was no significant correlation between total livestock print 
cover or cover of prints penetrating to the slickspot clay layer and 
abundance of L. papilliferum, and both the abundance of L. papilliferum 
per slickspot and proportion of flowering plants was similar between 
grazed and ungrazed transects for the single year of data reported in 
2004 (Menke and Kaye 2006b, p. 15). In the surrounding plant community, 
grazed and ungrazed transects had similar species richness, diversity, 
and soil crust cover, but total vascular plant cover and plant litter 
cover were significantly lower in grazed transects (Menke and Kaye 
2006b, pp. 15 and 16).
    Livestock trampling events that are 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 to 22). Saturated conditions 
typically exist for short periods each year and may never occur in some 
(drought) years (Hoffman 2005). Predicting when soils will be wet in a 
climate with few and inconsistent precipitation events is difficult. 
Consequently, managing livestock to avoid penetrating tramping events 
is difficult. Supplemental salt and watering sites can alter livestock 
distribution, and depending on location, can increase or decrease 
trampling of slickspots.
    At least two penetrating trampling events have been suggested as 
the cause of substantial losses in Lepidium papilliferum numbers. In 
1996, when other sites at the OTA had a reasonably high numbers of L. 
papilliferum individuals, a study site referred to as the ``States 
site'' experienced substantial declines. In 1993, this site had 
thousands of plants. In the spring of 1996, a trampling event disrupted 
or buried the in-situ seed bank (Meyer et al. 2005, pp. 21 and 22). 
Since this trampling event, fewer than 10 plants have been observed at 
the site despite yearly visits (Meyer et al. 2005, pp. 21 and 22). In 
another study area, four of five sites experienced increases in plant 
numbers; the fifth site, Glenn's Ferry, was the only one that incurred 
a trampling event, and the only one with a dramatic reduction in L. 
papilliferum numbers (Robertson 2003b, p. 8). Research designed to 
specifically examine the relationship between livestock use trampling 
effects and L. papilliferum is currently being conducted by University 
of Idaho and the State of Idaho in cooperation with us (State of Idaho 
et al. 2006, p. 119). However, at this point we have nothing but this 
anecdotal evidence to indicate a threat. Information we do have does 
not suggest that habitat threats are correlated with declines in 
species population levels.
    There are also indirect effects from livestock use that have 
impacted the sagebrush-steppe ecosystem. The spread of both native and 
nonnative plant species has been attributed to livestock use (Frost and 
Launchbaugh 2003, pp. 43 to 45). The spread of cheatgrass on the Snake 
River Plain has been attributed to several causes, including the past 
practice of heavy livestock use in the late 1800s (Mack 1981, pp. 145 
to 165). Today, nonnative, annual plants such as cheatgrass are so 
widespread that they have been documented spreading into areas that 
have not been disturbed (Piemeisal 1951, p. 71; Tisdale et al. 1965, 
pp. 349 and 351; Stohlgren et al. 1999, p. 45); therefore, the absence 
of livestock use does not protect the landscape from invasive, 
nonnative weeds (Frost and Launchbaugh 2003, p. 44). With careful 
management, livestock grazing may be used as a tool to select for 
certain native species or even to control cheatgrass (Frost and 
Launchbaugh 2003, p. 43).
    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). Analysis of HII data from 1999 
through 2001 found 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 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 been burned in the past (Menke and Kaye 
2006a, p. 18).
    The conservation plans (CCA, U.S. Air Force INRMP, IDARNG INRMP) 
contain numerous measures to avoid, mitigate, and monitor effects of 
livestock use on the species. Livestock grazing conservation measures 
implemented through the CCA and the U.S. Air Force INRMP apply to all 
Federal and State-managed lands (96 percent of the acreage) within the 
occupied range of Lepidium papilliferum. Conservation measures 
prescribed by the CCA include minimum distances for placement of salt 
and water troughs away from occurrences of the species, and several 
troughs and salt blocks have been moved as a result of these measures 
(State of Idaho et al. 2006, p. 133; State of Idaho et al. 2005). The 
CCA also includes measures to reduce 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 to 
134). High priority EOs, as identified in the CCA, tend to have more 
restrictive conservation measures, such as no early spring grazing, 
fencing to exclude livestock, and delaying turnout of livestock when 
soils are saturated (State of Idaho et al. 2006, pp. 133 to 134). High 
priority EOs were designated 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. In high priority 
EOs, greater emphasis is placed on protection and restoration of 
habitat. BLM has changed the season of grazing use from spring to fall, 
and implemented a deferred rotation management system on some 
allotments to protect flowering annuals from grazing (State of Idaho et 
al. 2006, pp. 133 to 134).
    Under the revised Juniper Butte Range INRMP, the U.S. Air Force 
will continue to use livestock throughout the majority of the Juniper 
Butte Range to reduce the amount of standing grass biomass to reduce 
wildfire risk (U.S. Air Force 2004, pp. 6-37 to 6-39). The grazing 
component plan for the INRMP states that livestock use will occur 
annually for up to 60 days while the bombing range is shut down for 
clean-up and target maintenance. The 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

[[Page 1638]]

emphasizes avoiding grazing when slickspots are wet in order to reduce 
trampling of slickspot habitats. It also provides guidance for annual 
monitoring of slickspot soil moisture to determine livestock turnout 
dates for Juniper Butte Range (U.S. Air Force 2000, pp. B-18 to B-21). 
The U.S. Air Force established three fenced areas of 173 ac (70.0 ha), 
8 ac (3.2), and 30 ac (12.1 ha), respectively, in 2002, with the intent 
of promoting Lepidium papilliferum research and seed collection (Binder 
2006), when compatible with the Air Force mission.
    There was no significant correlation between total livestock print 
cover or cover of prints penetrating to the slickspot clay layer and 
abundance of L. papilliferum, and both the abundance of L. papilliferum 
per slickspot and proportion of flowering plants was similar between 
grazed and ungrazed transects for the single year of data reported in 
2004 (Menke and Kaye 2006b, p. 15) and no other data were available 
that indicated otherwise. Therefore, we do not believe that livestock 
impacts are a threat to the species.
Residential and Agricultural Development
    Past residential and agricultural development has been responsible 
for five documented local extirpations and four probable local 
extirpations of Lepidium papilliferum (Colket et al. 2006, p. 4). The 
long-term viability of L. papilliferum occurrences on private land on 
the Snake River Plain has the potential to be compromised due to the 
continuation of residential and urban development in and around Boise 
(Moseley 1994, p. 20). Today, all or portions of 18 L. papilliferum EOs 
covering 457 acres (3.5 percent) (not including EOs managed by cities 
or counties) occur on private land. However, half of these 18 EOs are 
smaller than one acre, and most are classified as having fair to poor 
habitat quality (Colket et al. 2006, pp. 39 to 41). Residential and 
agricultural development can affect L. papilliferum and slickspot 
habitat through habitat conversion, increased nonnative plant 
invasions, increased off-highway vehicle use, increased wildfire, 
changes to insect populations, and increased fragmentation. Future 
residential and agricultural development on private land occupied by 
the species is a potential threat that is limited to 3.5 percent of the 
total known element occurrence acreage, therefore such development is 
not a significant threat.
    Gravel or cinder mining may affect Lepidium papilliferum on State 
and Federal lands (Mancuso 2000, p. 13). One site was impacted by 
illegal mining activity in 1999 on BLM and private lands (DeBolt 1999). 
No other impacts from gravel or cinder mining have been documented, 
therefore gravel or cinder mining does not constitute a significant 
threat to the species.
    Power, gas, and other lines, and related roads, affect and fragment 
Lepidium papilliferum EOs. Utility lines and accompanying roads have 
been documented running through at least four EOs, gas lines run 
through two EOs, and roads run through at least six EOs (Colket et al. 
2006, Appendix C). In addition to direct habitat destruction, these 
corridors allow off-road vehicle access and increase the chance of 
nonnative plant invasions and human-ignited wildfires. Transportation 
corridors associated with development also increase the probability of 
human-ignited wildfires and the spread of nonnative, invasive plants. 
Future developments associated with power, gas, other lines, and 
related roads through habitat occupied by the species may be a 
potential threat depending upon design and mitigation measures 
associated with the developments. But at this time we have no data that 
such development constitutes a significant threat to the species.
    Of the Lepidium papilliferum EOs for which habitat information has 
been collected, 14 of 75 (13 of 60 on the Snake River Plain and 1 of 15 
on the Owyhee Plateau) have development (e.g., utility lines, mining, 
agricultural development, and residential development) within them, and 
28, all on the Snake River Plain, have development adjacent to them 
within 0.31 mi (500 m) (Colket et al. 2006, Appendix C). On the Owyhee 
Plateau, one EO has development occurring within it, and no EOs have 
development within 0.31 mi (500 m) (Colket et al. 2006, Appendix C).
    Within the Snake River Plain, an estimated 327,549 ac (132,554 ha) 
(20 percent) has been converted to agriculture (IDWR 1999), and 94,974 
ac (38,435 ha) (6 percent) has been converted to urban areas 
(University of Idaho 2001).
    Development was not a parameter that was measured in 2004 through 
the HIP transect monitoring program (Colket 2005a). In 2005, 79 HIP 
transects were monitored (57 on the Snake River Plain and 22 on the 
Owyhee Plateau); of these transects only one transect on the Snake 
River Plain had development occurring at the transect (in this case 
residential/commercial). Monitoring in 2005 on the Snake River Plain 
also documented residential and commercial development occurring within 
0.31 mi (500 m) of 17 transects, and agricultural development was 
documented adjacent to 10 transects (Colket 2005b, Table 2).
    Currently, the effects from development to Lepidium papilliferum 
are confined geographically to the Snake River Plain, however these 
threats are not significant. Development does not appear to be a threat 
at all for L. papilliferum EOs on the Owyhee Plateau.
Nonnative Seeded Species
    A decline in habitat quality for Lepidium papilliferum since 1998 
in terms of decreased vascular plant cover, species richness, and 
species diversity was noted by Menke and Kaye (2006b, p. 19), although 
they found no change in the cover of exotic grasses or forbs in the 
plant community between 1998 and 2004, and no relationship between 
short-term abundance of L. papilliferum and weedy species cover in 
slickspots (Menke and Kaye 2006b, p. 15). At this time, we have no data 
supporting a conclusion that longer-term abundance will be negatively 
affected by the presence of exotic grasses.
    Rangeland revegetation priorities on public lands in southeast 
Idaho have included providing forage for livestock, erosion control, 
wildfire prevention, reducing nonnative annual grass density, and 
watershed rehabilitation. Some nonnative perennials can out-compete 
native species and decrease biodiversity (summarized by Harrison et al. 
1996, 62 pp.). For example, crested wheatgrass, a forage species that 
was once commonly planted within the range of Lepidium papilliferum, is 
a competitor and its seedlings are better than some native species at 
acquiring moisture at low temperatures (Lesica and DeLuca 1998, p. 1; 
Pyke and Archer 1991, p. 4; Bunting et al. 2003, p. 82). The results 
from surveys conducted on the Owyhee Plateau by (Popovich 2002, p. 16) 
indicated that the number of L. papilliferum plants per site was lower 
in habitat with crested wheatgrass seedings, compared to native 
sagebrush-steppe habitat areas or burned areas that had not been seeded 
(Popovich 2002, p. 16). Forage kochia (Bassia prostrata, formerly 
Kochia prostrata) is another nonnative species that has been used for 
rangeland habitat restoration. Thousands of forage kochia plants have 
been observed in relatively small slickspots, and it is documented as a 
direct competitor with L. papilliferum in slickspots (DeBolt 2002; 
Quinney 2005). In one study area within the Poen fire rehabilitation 
project, post-wildfire monitoring over a 6-year period following aerial 
seeding with forage

[[Page 1639]]

kochia showed eventual loss of L. papilliferum along the monitoring 
transect, and a dramatic increase in forage kochia (DeBolt 2002). Four 
other slickspots, containing a total of 31 individual L. papilliferum 
plants and numerous forage kochia plants in 2000, were void of L. 
papilliferum and dominated by forage kochia in 2005 (Quinney 2005). 
Blue flax (Linum lewisii) is another nonnative seeded plant that was 
found within HIP transects (Colket 2005a, p. 6). It is not clear why 
these L. papilliferum plants were absent.
    Nonnative seeded species exist in 23 of the 75 EOs with documented 
habitat information (17 of 60 on the Snake River Plain and 6 of 15 on 
the Owyhee Plateau), and 18 (14 on the Snake River Plain and 4 on the 
Owyhee Plateau) have non-native seeded species adjacent to the EO 
within 0.31 mi (500 m).
    The effects of invasive, nonnative seeded plants are monitored as 
parts of HIP range-wide transect monitoring for Lepidium papilliferum. 
In 2004, 71 L. papilliferum HIP transects (49 on the Snake River Plain 
and 22 on the Owyhee Plateau) were measured (Colket 2005a, pp. 46 to 
47). Results indicate that 11 transects within the Snake River Plain 
and 13 transects within the Owyhee Plateau had introduced perennial 
plant cover (nonnative, seeded species) (Colket 2005a, pp. 46 to 47). 
In general, the documented high percentage of plant cover in the 2004 
HIP transect monitoring is attributable to crested wheatgrass, except 
at the site with the highest percent cover. This site in the Snake 
River Plain contained 26.8 percent cover in forage kochia (Colket 
2005a, pp. 17, 32). 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 wildfire rehabilitation efforts (U.S. Air 
Force 1998, pp. 31-120 to 3-121).
    Although the use of native plant species for wildfire 
rehabilitation is preferable, previously there have been problems with 
the availability and high cost of native seed (Jirik 1999, p. 110; 
Brooks and Pyke 2001, p. 9). In recent years, with an increase in 
research and agencies (e.g., BLM) investing heavily in projects such as 
the Great Basin Native Plant Selection and Increase Project and the 
Great Basin Restoration Initiative, native seeds and plants are more 
available to use in restoration of sagebrush-steppe habitat. However, 
restoration of sagebrush-steppe habitat, and Lepidium papilliferum 
habitat in particular, is still considered a difficult and expensive 
task.
    Under current policies, BLM no longer uses forage kochia as a 
wildfire rehabilitation species in Lepidium papilliferum habitat (USBLM 
2002). BLM emphasizes the use of native plants, including forbs, in 
seed mixes and avoids the use of invasive, nonnative species (State of 
Idaho et al. 2006, p. 26). In January 2004, BLM issued an Instruction 
Memorandum to employees on compliance with CCA requirements for 
emergency stabilization and wildfire rehabilitation activities (State 
of Idaho et al. 2006, p. 71).
    The military has a number of ongoing efforts to address invasive 
nonnative, seeded plants. These efforts are implemented and effective 
in reducing this threat. The U.S. Air Force uses only non-invasive 
plant materials and will not use forage kochia, intermediate wheatgrass 
(Thinopyrum intermedium, formerly Agropyron intermedium), or salt-
tolerant species such as four-wing saltbush (Atriplex canescens) in 
revegetation efforts, with native plants being used to the maximum 
extent practicable and in concert with the military mission for 
rehabilitation efforts (U.S. Air Force 2004, p. R-4). The IDARNG INRMP 
for the OTA includes the objectives for maintenance; where possible, 
improvement of Lepidium papilliferum habitat; and restoration of areas 
damaged by wildfire, through native species and broadcast seeding, 
collecting, and planting small amounts of native seed not commercially 
available, and monitoring the success of seeding efforts (IDARNG 2004, 
p. 72 to 73). Since 1991, the IDARNG has examined historical records 
and has seeded areas back to the native vegetation that was present 
prior to past wildfires. Care is taken to ensure that restoration does 
not damage L. papilliferum or its habitat, or introduce species into 
the habitat that were not present in presettlement times (IDARNG 2004, 
p. 73).
    The IDARNG has demonstrated that diligent efforts to suppress 
wildfire, the use of native species, and minimal ground-disturbing 
wildfire rehabilitation activities can be effective in reducing the 
wildfire threat and rates at which nonnative species spread. Because of 
limited rainfall and harsh conditions, restoration is a difficult task 
and often requires repeated seedings on the OTA (IDARNG 2004, p.73). 
Methods currently used by the IDARNG may not be economically feasible 
for revegetation of large areas of damaged habitat found in other parts 
of the range of the species.
    Menke and Kaye (2006b, p. 19) evaluated rangewide data from 1998-
2004 and found a decline in the quality of habitat surrounding 
slickspots occupied with Lepidium papilliferum in terms of decreased 
vascular plant cover, species richness, and species diversity. They 
found no change in the cover of exotic grasses or forbs in the plant 
community between 1998 and 2004, and no relationship between short-term 
abundance of L. papilliferum and weedy species cover in slickspots 
(Menke and Kaye 2006b, p. 15). Because abundance cannot be correlated 
with habitat changes, we find that a decline in habitat quality is not 
threatening the species.
Wildfire Management and Post-Wildfire Rehabilitation
    Activities associated with wildfire management include fuel 
management projects (e.g., greenstrips, prescribed fire), wildfire 
suppression activities, and post-wildfire rehabilitation. These 
activities can potentially impact existing Lepidium papilliferum 
occurrences and damage slickspot habitat (ILPG 1999) by the 
establishment of nonnatives or by mechanical disturbances.
    Drill seeding is a rehabilitation technique that is used after 
wildfire. Drill seeding uses a rangeland drill that plants and covers 
seed simultaneously in furrows. It is designed to give the seeds 
moisture and temperature advantages that will enhance their competitive 
fitness and, consequently, their success 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, and so no attempt was 
made to avoid them during rehabilitation activities. We have no data on 
the extent that drill seeding may still be affecting L. papilliferum 
habitat, although some habitat areas have buffers established to 
protect them.
    Disk or drill seeding has occurred on 14 of 60 EOs on the Snake 
River Plain and 10 of 15 EOs on the Owyhee Plateau (Colket et al. 2006, 
Appendix C). Drill seeding may have less severe impacts on slickspot 
habitat than disking the soil, but the success of restoring slickspots 
and Lepidium papilliferum plants varies considerably. The benefits of 
post-fire revegetation, and subsequent recovery of soil surfaces 
conducive to germination and establishment of native perennial grass 
and shrub communities, may outweigh the initial short-term disturbance 
associated with drill

[[Page 1640]]

seeding (Young and Allen 1996, pp. 533 to 534; Bunting et al. 2003, pp. 
82 to 85).
    Ground disturbance associated with wildfire control, such as 
establishment of fire lines (areas with vegetation removed to break 
fuel continuity), fire camps, and staging areas, and the use of 
wildfire suppression vehicles, can also impact existing Lepidium 
papilliferum occurrences and damage slickspot habitat (ILPG 1999). 
Similarly, construction of fuel breaks, while beneficial in slowing the 
movement of wildfire, may also impact L. papilliferum through ground 
disturbance or the use of invasive, nonnative, seeded species. Only two 
EOs, both on the Snake River Plain, are documented as having wildfire 
lines within them, although neither has documented wildfire lines 
within slickspots (Colket et al. 2006, Appendix C). Herbicides used to 
pretreat rehabilitation areas prior to seeding may also impact L. 
papilliferum. These activities may injure or kill individual plants or 
the seed bank through mechanical disturbance or direct exposure to 
herbicides. Indirect effects associated with mechanical disturbance of 
slickspot soils include increased probability of establishment of 
invasive, nonnative plants, burying of the seed bank to a depth where 
seedlings cannot emerge from the soil, and mixing of slickspot soil 
layers, which affects the suitability of a microsite for the species.
    The effect of drill seeding is monitored as part of the HIP range-
wide transect monitoring. In 2004, of the 71 Lepidium papilliferum 
transects monitored, 3 transects on the Snake River Plain and 5 
transects on the Owyhee Plateau had evidence of old drill seedings 
within slickspots; no transects had evidence of firefighting 
disturbances within slickspots (Colket 2005a, pp. 44 to 45).
    Through the CCA, BLM has implemented a number of conservation 
measures to avoid or minimize impacts to the species from wildfire 
prevention, wildfire suppression, and post-wildfire emergency 
rehabilitation activities. These measures are effective to reduce this 
threat at least partially. BLM and fire cooperators distribute maps and 
inform crew members of the location of Lepidium papilliferum to 
maximize wildfire protection in those areas, and to minimize potential 
impacts from suppression related activities (State of Idaho et al. 
2006, p. 26). Per conservation measure .08 of the CCA, BLM uses seeding 
techniques that minimize soil disturbance, such as no-till drills and 
rangeland drills equipped with depth bands, when rehabilitation and 
restoration projects have the potential to impact occupied or suitable 
habitat (State of Idaho et al. 2006, p. 26). Rehabilitation and 
restoration standard operating procedures for L. papilliferum were 
issued in an Instruction Memorandum in January 2004 (State of Idaho et 
al. 2005, p. 33). BLM avoids spraying herbicides within or near known 
occupied habitat, and conducts pretreatment surveys of 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).
    The military has a number of ongoing, effective efforts to address 
wildfire management activities. The potential for wildfire ignition and 
spread are decreased by the placement of appropriate restrictions on 
activities, and the use of wildfire indices to restrict activities when 
the wildfire rating hazard is extreme (U.S. Air Force 2004, p. R-3). 
The U.S. Air Force uses drill seeders equipped with depth bands to 
avoid unnecessary disturbance to soils, avoids slickspots to the 
maximum extent practicable in drill seeding efforts, and uses broadcast 
seeding to the maximum extent practicable consistent with reseeding 
goals (U.S. Air Force 2004, p. R-4). The IDARNG restores wildfire-
damaged areas using native species and broadcast seeding. Similarly, 
the IDARNG provides their fire crews with maps of all known occupied 
habitat, and actively suppresses all wildfires on the OTA. Blading is 
not permitted in Lepidium papilliferum habitat areas on the OTA. 
Existing roadways serve as fuel breaks within the OTA, 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 fire 
rehabilitation activities can be effective in reducing the wildfire 
threat and reducing establishment rates of nonnative, unseeded species 
associated with wildfire management activities (IDARNG 2004, p. 73).
    Wildfire management has positive consequences (i.e., the control of 
wildfires) and potentially negative consequences (i.e., destruction of 
slickspots through habitat restoration and wildfire control practices), 
depending on how the activity is implemented. The Expert Panel 
considered wildfire management to be less of an impact than the first 
four factors discussed above. After our review of the available data, 
we have determined that wildfire management can potentially impact 
Lepidium papilliferum, although this activity is not threatening the 
species.
Recreation
    Recreational activities that may affect Lepidium papilliferum 
include hiking, horseback riding, and off-highway vehicles. Juniper 
Butte Range and areas of the OTA are protected from recreational 
activities because of military restrictions.
    Off-highway vehicle use has been documented in 16 of the 75 EOs (16 
of 60 on the Snake River Plain, none on the Owyhee Plateau) for which 
habitat information has been collected (Colket et al. 2006, Appendix 
C).
    Effects from recreational activities are monitored as part of the 
HIP range-wide transect monitoring for Lepidium papilliferum. In 2004, 
3 of 49 transects on the Snake River Plain showed off-highway vehicle 
tracks within the EO area, and 1 transect had off-highway vehicle 
tracks directly through it (Colket 2005b, Table 1). In 2005, two EOs on 
the Snake River Plan had tracks in the general occurrence area, and one 
had tractor tracks running through the transect (Colket 2005b, Table 
1). New tracks are documented each year, so monitoring reports are not 
cumulative. Off-highway vehicle use was also monitored within the 
Owyhee Plateau L. papilliferum EOs in 2004 and 2005, but no off-highway 
use was documented. An analysis of HII transects between 1998 and 2001 
indicated that only a few transects had OHV use in each year, that 
impacts appeared to be minimal, and that OHV use regionally does not 
appear to be a major agent of habitat degradation, while noting that 
concentrated OHV use in localized areas could potentially be more 
problematic (Menke and Kaye 2006a, p. 18). Therefore, we have 
determined from the available data that any potential impact to 
Lepidium papilliferum from recreation appears to be localized. 
Additionally, we have no data indicating that recreation is a major 
agent of habitat degradation and therefore is not threatening the 
species.

Military Training

    Military activities within the range of Lepidium papilliferum 
include ordnance impact areas, training activities, military 
development, and an increased risk of wildfire and nonnative plant 
invasions. Military training occurs on the Snake River Plain at the OTA 
(seven EOs) and on the Owyhee Plateau at the Juniper Butte Range (a 
portion of one EO). INRMPs developed for both the Juniper Butte Range 
and the OTA provide management direction reducing or eliminating many 
of these threats

[[Page 1641]]

from military training exercises. The OTA, where 14 years of INRMP 
conservation efforts have been implemented, is considered the most 
intact, native L. papilliferum habitat range-wide (Colket et al. 2006, 
pp. 22 to 23; Meyer 2005, p. 1).
    The IDARNG and the U.S. Air Force are implementing various 
conservation efforts to avoid or reduce adverse effects of military 
training on the species and its habitat, and the IDARNG has had 
measures in place that promote the conservation of Lepidium 
papilliferum prior to revisions to the IDARNG INRMP made in 2004. The 
threat of military training is localized in area, and minimal in 
significance across the range of the species.
Summary of Factor A
    There is little disagreement that the quality and composition of 
the sage-brush steppe ecosystems that surrounds the slickspot 
microsites inhabited by Lepidium papilliferum has become degraded over 
time. Increased fire frequencies largely caused by the invasion of 
exotic annual grasses are of particular concern, as are potentially 
destructive penetrating trampling events of slickspots by livestock. 
What is not clear is the relationship between these factors and the 
long-term persistence or viability of L. papilliferum. What little data 
we have at this time does not indicate any direct relationship between 
the abundance of L. papilliferum and factors such as livestock use and 
weedy species cover. Burning appears to have a negative impact on 
slickspot conditions, such as increasing exotic species cover and 
decreasing soil crust cover, but these factors were not significantly 
correlated with L. papilliferum abundance. Accordingly we find that L. 
papilliferum is not threatened by habitat changes to the extent that 
protection under the Act is needed.

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

    Herbivory of Lepidium papilliferum is reported as sparse. Herbivory 
by rodents and insects has been occasionally observed on L. 
papilliferum plants. In one instance, grasshoppers (possibly Acrididae) 
were observed consuming L. papilliferum flower petals (Geertson 2004, 
p. 3). We are unaware of any specific studies documenting foraging on 
L. papilliferum by Mormon crickets (Anabrus simplex). Insect herbivores 
have been studied as part of pollinator and reproductive biology 
studies (Robertson et al. 2004). Flower petal herbivory of L. 
papilliferum by chrysomelid beetles (Phyllotreta spp.) was shown to be 
detrimental to seed production because of decreased pollinator 
visitation; pollinators did not visit flowers with missing flower 
petals. Other insect herbivores include plutellid moth larvae, which 
eat all portions of the plant; harvester ants which eat entire fruits 
or leaves from plants; mirid bugs, which probably suck phloem; 
grasshoppers (Acrididae); and leafhoppers (Cicadellidae), which 
probably suck phloem (Robertson et al. 2004, p. 12). At three different 
sites (one at Kuna Butte and two at the Orchard Training Area), 35 
percent, 37 percent, and 23 percent of plants showed evidence of insect 
herbivore damage (Robertson et al. 2004).
    Herbivory impacts to L. papilliferum from large, native ungulates, 
such as elk, deer and antelope, have not been observed. However, 
pronghorn antelope tracks and droppings (U.S. Air Force 2003, p. 14) 
and elk tracks and droppings (State of Idaho et al. 2006, Appendix A) 
have been infrequently documented in slickspots that support L. 
papilliferum. Domestic sheep have been observed pulling the plants from 
the ground and spitting them out (Quinney and Weaver 1998). Herbivory 
by cattle has not been observed.
    We have no data to support the conclusion that disease or predation 
are a significant threat to Lepidium papilliferum.

D. Inadequacy of Existing Regulatory Mechanisms

    Lepidium papilliferum is considered a sensitive species by BLM (BLM 
2003, p. 2-1). BLM has regulations that address the need to protect 
sensitive, candidate, and federally listed species, and BLM has 
initiated monitoring of L. papilliferum on Federal lands. Monitoring 
can be used to identify threats, which can result in management actions 
necessary for controlling L. papilliferum habitat degradation.
    As a signatory of the CCA (State of Idaho et al. 2003, 2006), BLM 
is the primary land management agency implementing conservation efforts 
for this species. The majority of implemented conservation efforts 
associated with the CCA occur on BLM lands. In recent years, BLM has 
initiated efforts to conserve the species, and the CCA represents a 
major commitment by BLM for management of lands that account for a 
majority of the range of the species (87 percent of the total area and 
portions of 71 of the 85 extant EOs). Conservation efforts are not a 
basis for our finding here, but ongoing conservation efforts will be 
helpful in offsetting any effects that do occur from potential threats, 
and further voluntary conservation efforts are encouraged. Therefore, 
available data does not suggest that existing regulatory mechanisms are 
inadequate.

E. Other Natural or Manmade Factors Affecting Its Continued Existence

    The Expert Panel identified unpredictable rain events and drought 
as climate factors affecting Lepidium papilliferum, but did not 
consider them to be significant threats to the species. We have no data 
that climatic patterns of rainfall will significantly change over time. 
Therefore, we do not consider drought or lack of rainfall to pose an 
extinction risk, although it can cause a short-term decline in 
population numbers. No other threats to L. papilliferum were identified 
under Factor E.

Summary of Factors Affecting the Species--Conclusion

    The primary factors affecting Lepidium papilliferum are habitat 
based. We examined other potential threats and determined that the 
available data does not suggest that the other factors are threatening 
the species. We examined data available for effects of wildfire 
frequency, invasive nonnative plants (especially annual grasses), 
livestock impacts, and residential and agricultural development. While 
disturbances to L. papilliferum can result from wildfire, commercial 
and residential development, livestock use, and ground-disturbing 
wildfire management practices or recreation activities the available 
data did not support a finding that the species is threatened by one or 
more of these potential threats. Our analysis of the factors affecting 
the species indicates that there is cause for concern regarding the 
decline in quality of the sagebrush-steppe ecosystem and the slickspot 
microhabits within. We examined the increased frequency of fires, 
fueled largely by invasive exotic annual grasses, and how it is 
altering the diversity and composition of the native plant community. 
We found that there was no evidence that habitat degradation is a 
threat to the species such that listing is warranted at this time. 
However, the concerns generated by our analysis emphasize the need for 
further research and support for ongoing efforts to restore and manage 
the

[[Page 1642]]

sagebrush steppe ecosystem. This also underscores the necessity for 
close monitoring of L. papilliferum and other components of the 
sagebrush community to better determine the response of these species 
to the alteration of their environment. The best available data do not 
demonstrate any relationship between altered habitat conditions and the 
status of L. papilliferum. The limited data available do not 
demonstrate any significant relationship between the abundance of L. 
papilliferum and factors such as livestock use or weedy species cover. 
The two available datasets of abundance monitoring present conflicting 
results regarding the trend of the population over time. The population 
of L. papilliferum is positively correlated with spring precipitation. 
L. papilliferum evolved in an arid environment and has adapted to 
fluctuations in precipitation. We have no data demonstrating that 
precipitation levels are varying significantly from historical 
patterns. Accordingly, we do not find that fluctuation in precipitation 
is a threat to the species.

Status Review Process

    Section 4(b)(1)(A) of the Act requires us to consider the best 
scientific and commercial data available, as well as efforts being made 
by States or other entities to protect a species, when making a listing 
decision. To meet this standard, we systematically collected 
information on Lepidium papilliferum, its habitats, and environmental 
factors affecting the species from a wide array of sources. In 
addition, we received a substantial amount of unpublished information 
from other Federal agencies, States, private industry, and individuals. 
We solicited information on all Federal, State, or local conservation 
efforts currently in operation or planned for either L. papilliferum or 
its habitat.
    In addition, we convened an Expert Panel of seven independent 
scientists who assisted in evaluating the available data and discussed 
threats to L. papilliferum. Expert Panels are not a required component 
of our analysis, but are used occasionally by the Service to help 
inform decision makers when there is uncertainty. Scientific 
information on Lepidium papilliferum and associated habitat is limited; 
data gaps and uncertainty exist in the scientific community's knowledge 
of threats that may affect L. papilliferum populations across its 
geographical range of sagebrush-steppe habitat. For these reasons, we 
requested input from scientific experts to help us assess the status of 
L. papilliferum. The Expert Panel consisted of experts in the fields of 
small populations/fragmentation, annual desert plants, sagebrush 
community ecology, wildfire/nonnative species, soils and livestock use, 
and L. papilliferum. The discussion of the Expert Panel, and other 
available data, was then considered by our Manager Panel in order to 
develop the decision reported in this finding.
    We conducted three phases of information synthesis and evaluation. 
First, the information on individual planned conservation efforts was 
evaluated to determine which of the efforts that have not yet been 
implemented, or have been implemented but have not yet demonstrated 
whether they are effective, met the standard for sufficient certainty 
of implementation and effectiveness in the Policy for Evaluating 
Conservation Efforts (68 FR 15115, March 28, 2003). Second, we employed 
the assistance of an Expert Panel that evaluated all factors possibly 
affecting the species' current status. Subsequent to the work done by 
the expert panel new information became available. Our Manager Panel 
evaluated all the information, including the new information, on 
status, trends, ongoing conservation efforts, and potential risk to 
determine whether the species should be listed as threatened, listed as 
endangered, or not warranted for listing. We structured these three 
phases by differentiating two distinct stages of the analysis: (1) A 
risk analysis phase that included compiling biological information and 
estimating the risk to the species; and (2) a risk management phase 
where our Manager Panel evaluated whether the potential threats 
identified as part of our section 4(a)(1) analysis, and summarized in 
this finding, qualify Lepidium papilliferum as a threatened or 
endangered species under the Act.

Policy for Evaluation of Conservation Efforts

    PECE provides a framework and criteria for evaluating conservation 
efforts that have not been implemented or have not demonstrated whether 
they are effective at the time of a listing decision. Recognizing that 
the certainty of implementation and effectiveness of various planned 
efforts within a conservation plan, strategy, or agreement may vary, 
PECE requires that we evaluate each individual conservation effort that 
has not been implemented or for which effectiveness has not been 
demonstrated, and the policy provides criteria to direct our analysis. 
PECE specifies that to consider that a conservation effort(s) 
contributes to forming a basis for not listing a species or listing a 
species as threatened rather than endangered, we must find that the 
conservation effort is sufficiently certain to be implemented and 
effective so as to have contributed to the elimination or adequate 
reduction of one or more threats to the species identified through the 
section 4(a)(1) analysis. (68 FR 15115, March 28, 2003). Thus, PECE is 
relevant in situations where a threats analysis, conducted without 
consideration of conservation efforts that meet the standard in PECE, 
indicates that listing is warranted. In such situations, we then 
consider the effect of conservation efforts that meet the ``sufficient 
certainty'' standard in PECE to determine whether such efforts have 
contributed to the elimination or adequate reduction of threats, 
leading to a determination that the species does not meet the 
definition of threatened or endangered and therefore does not warrant 
listing, or that that listing as threatened, rather than endangered, is 
appropriate.
    Because of the time needed to evaluate large numbers of individual 
conservation efforts under PECE, it sometimes is necessary to proceed 
with the evaluation process prior to completing the threats analysis 
pursuant to section 4(a)(1) of the Act, i.e., before we have determined 
whether efforts that meet the standard in PECE will actually play a 
role in our determination. That was the case in this situation.
    For the PECE analysis, we reviewed activities identified in five 
plans or conservation strategies. The five plans were: (1) The 
Candidate Conservation Agreement for Slickspot Peppergrass; (2) the 
Idaho Army National Guard Integrated Natural Resource Management Plan 
for Gowen Field/Orchard Training Area; (3) the U.S. Air Force 
Integrated Natural Resource Management Plan for Mountain Home Air Force 
Base; (4) the 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 Lepidium papilliferum 
(slickspot peppergrass); and (5) the Conservation Agreement for 
Slickspot Peppergrass (Lepidium papilliferum) at the Boise Airport, Ada 
County, Idaho.
    We reviewed each conservation effort contained in the five 
conservation plans to determine which had been implemented and 
demonstrated effectiveness in reducing one or more threats. We relied 
on available documentation to determine if the effort was implemented 
by the time of our analysis. As explained above, conservation efforts 
that have been

[[Page 1643]]

implemented and demonstrated effectiveness are not subject to 
evaluation under PECE, and are considered as part of the section 
4(a)(1) threats analysis (below). We also used the criteria in PECE to 
evaluate efforts that had not been implemented, and efforts that had 
been implemented but had not yet demonstrated whether they were 
effective. We did not rely on those efforts that met the PECE standard 
in our determination. We made our determination on the basis of the 
threats analysis and information about population status and trends 
(see below). However, we consider the conservation plans and the 
continued commitment of stakeholders to implement the conservation 
efforts important to the long-term sustainability of Lepidium 
papilliferum.

Expert Panel

    In May 2006, we convened a panel composed of seven experts to 
provide assistance in understanding the ecology and biology of Lepidium 
papilliferum, to assess the threats and extinction risk to the species, 
and to identify areas of scientific uncertainty. The panelists brought 
a variety of expertise to the discussion, including knowledge and 
experience with wildfire, nonnative species, range and grazing issues, 
soils, small populations and fragmentation, annual desert plants, and 
sagebrush community ecology, and included a L. papilliferum species 
expert.
    The top two potential threats identified by the Expert Panel were 
the invasion of cheatgrass and the subsequent changes to the fire 
regime in the sagebrush-steppe ecosystem. Several members of the panel 
agreed that the expansion of cheatgrass will likely create annual 
grasslands that will dominate the Snake River Plain within the next 50 
years, and would impact Lepidium papilliferum and its habitat. The 
invasion of exotic annual grasses in turn increases the frequency of 
fire, leading to further alterations of the native plant community.
    Following the May 2006 Expert Panel, the Service received 
additional information including new analysis of Lepidium papiliferum 
population and habitat monitoring data (e.g., Menke and Kaye 2006b). 
This information was not available to the expert panel and did not 
factor into their extinction risk estimates. The Service considers the 
extinction risk estimates by the expert panel to be informative in that 
they provide a context in which we were able to assess the new 
information. However, the estimates have limited applicability to our 
determination in light of this new information. In particular, the new 
information limits the Service's confidence in extrapolation of  L. 
papilliferum population trends at the OTA to population trends in the 
remaining Snake River Plain metapopulation and the range-wide 
population.

Manager Panel

    Our Manager Panel reviewed background materials, interacted with 
the Expert Panel during their exercises, and participated in 
discussions about the application of the Act and specific terms 
contained in the Act. The managers based their assessments on the data 
in the record, including comments previously received; the data 
presented by the individual members of the Expert Panel, as well as 
data received subsequent to the Expert Panel process; known information 
gaps and uncertainty; the number and severity of the threats affecting 
the species; and mitigating circumstances that might ameliorate one or 
more of the threats. The Manager Panel convened on three occasions. 
This rule is based on the record of these discussions and all relevant 
and available information pertaining to the threats to and status of 
the species.

Determination

    We examined the data regarding L. papilliferum populations and 
occurrence as well as the specific habitat needs of the species. We 
included an examination of habitat degradation and modification to the 
sagebrush-steppe ecosystem and the slickspot microhabitats from the 
current wildfire regime (i.e., increasing frequency, size, and 
duration), invasion of non-native weed species (e.g., cheatgrass), 
effects of livestock use (e.g., penetrating trampling, disruption of 
soil crust covers), and residential and agricultural development to 
determine whether there were any resulting effects on L. 
papilliferum.While the sagebrush steppe-ecosystem has experienced 
decreased native shrub cover and increased exotic grass cover, we have 
no data demonstrating that these factors affect L. papilliferum 
populations. Data at this point are limited and based on observational 
measures rather than controlled experiments, but indicate no 
significant relationship between the abundance of L. papilliferum and 
factors such as livestock use or weedy species cover in slickspots. The 
data limitations point to the value of the conservation activities and 
collection of data and to improve our understanding of the species, as 
well as preventive actions. However, we do not have evidence that the 
factors evaluated here have led to a negative population trend range-
wide in L. papilliferum.
    Determining range-wide abundance and population trends of Lepidium 
papilliferum is complicated by its annual and biennial life histories 
and its correlation to spring precipitation, which can vary widely from 
year to year. Spring rainfall patterns also vary at the local scale, 
which can influence abundance of the plant from one population to 
another in the same local area. Abundance estimates are confounded 
because seeds can remain dormant (and viable) in the seed bank for at 
least 12 years. All of these factors lead to great natural variability 
in the abundance of L. papilliferum from year to year, which confounds 
our assessment of population trends.
    Currently we have two relatively long-term datasets of abundance 
monitoring for Lepidium papilliferum on which to base our evaluation of 
population trends for this species, the data from the OTA and the data 
from range-wide HII and HIP monitoring (which includes several 
transects on the OTA). The dataset from the OTA indicates recent 
declines in the abundance of the species that do not correlate as 
expected with patterns of spring precipitation, beginning in 2003 
(Weaver 2006, pp. 1-6). Data from the range-wide HII and HIP transects 
demonstrate that although the population declined following one of its 
highest recorded peaks in abundance in 1998 (the first year for which 
HII data was available), the range-wide population then stabilized and 
began increasing after 2003 (Menke and Kaye 2006b, Figure 3; USFWS 
2006f, Figures 8, 9). The range-wide data show increases in populations 
since 2003, and populations have continued to show a positive 
relationship to spring precipitation. The available data are not 
consistent with regard to an overall population trend for L. 
papilliferum. The data from OTA indicate that plant abundance declined 
after 1995 and was generally correlating with spring precipitation 
until 2003 through present when plant abundance did not increase with 
higher levels of spring precipitation. Range-wide data indicate that L. 
papilliferum abundance has correlated with spring precipitation and 
abundance of the plant range-wide has increased since 2004 to levels 
comparable to 1998 range-wide data. We consider this range-wide data to 
be the best available at this time.
    Identification of data gaps and uncertainties helps explain the 
limits of our understanding of future risk to Lepidium papilliferum. We 
are required to make a determination whether the species qualifies as 
threatened or

[[Page 1644]]

endangered under the Act based solely on the best available scientific 
and commercial data. To ensure that we considered this data in the 
proper context, the Manager Panel (see Status Review Process) 
participated in a structured analysis that included an evaluation of 
the Act's statutory requirements, in particular the Act's definitions 
of threatened and endangered, and a review of the data from the risk 
analysis and all other compiled biological information. They considered 
the data about risks to L. papilliferum, including explicit measures of 
uncertainty, and the data supporting the existence of those risks, in 
the context of the requirements of the Act. The definitions in the Act 
include: an endangered species is in danger of extinction throughout 
all or a significant portion of its range, and a threatened species is 
likely to become an endangered species within the foreseeable future 
throughout all or a significant portion of its range (16 U.S.C. 
1532(6), (20)).
    The Manager Panel convened on three occasions: once during the 
science panel and shortly after the science panel in May 2006, and 
again in November 2006.
    When the Manager Panel convened in November 2006, focal points of 
discussion included results of the Menke and Kaye 2006 report that was 
not available at the time of the science panel and new insights gained 
from public comment and review of monitoring results. Of particular 
note were the results that spring precipitation (March-May) explained 
89 percent of the variation in plant abundance for the years 1998-2001, 
2002, and 2004 sampled by range-wide HII and HIP transects (Menke and 
Kaye 2006b, p. 10). In addition, this report demonstrated a consistent 
correlation between the abundance of Lepidium papilliferum and spring 
rainfall throughout all years and reported population increases range-
wide since 2003, which contradicted trends reported based on data from 
the OTA.
    Upon reviewing the studies and plant abundance data, the Manager 
Panel concluded that indications of declines in plant abundance at OTA 
cannot be reasonably extrapolated to the range-wide population of 
Lepidium papilliferum, and that the conflicting data indicating range-
wide population increases in recent years from the HII and HIP 
transects add additional uncertainty to our ability to assess the 
nature of any population trend for L. papilliferum. The high 
variability in plant numbers from year to year, expected for an 
ephemeral annual plant with a dormant seed bank that is highly 
dependent on seasonal rainfall, increases the difficulty of discerning 
any trend in abundance data over time. Although the quality of the 
sagebrush-steppe slickspot habitat of L. papilliferum has become 
degraded due to a variety of threats, the existing data do not support 
a determination that those threats are affecting L. papilliferum across 
all or a significant portion of its range sufficient to require the 
protections of the Act at this time. The managers decided that the data 
before them did not support a determination that L. papilliferum is 
exhibiting a population decline. The available data do not lead us to 
conclude that the species is declining range-wide, thus we are unable 
to establish that there is a point in time when the species is likely 
to be in danger of extinction throughout all or a significant part of 
its range. The district court decision found that our previous analysis 
of foreseeable future was unsupported in the record. In particular, the 
court noted that the expert panel concluded that there was a 64-80 
percent chance that L. papilliferum would become extinct in the next 
100 years. Thus, the court thought that our ultimate conclusion that 
the species was not likely to become in danger of extinction in the 
foreseeable future depended upon a preliminary conclusion that the 
foreseeable future was in this case a period of time considerably less 
than 100 years. Because the court found that we had not adequately 
explained why the Service selected the timeperiod it did for 
foreseeable future, the court held that our determination was arbitrary 
and capricious. In contrast, given the new information, the question of 
how much of the future is foreseeable is no longer relevant. We 
conclude that apparent abundance of the plant can fluctuate widely from 
one year to the next, and abundance is strongly correlated with spring 
precipitation. We have no data demonstrating that precipitation levels 
are varying significantly from historical patterns. L. papilliferum 
evolved in an arid environment and has adapted to fluctuations in 
precipitation by a strategy of relatively long-term seed viability and 
by increased seed production during favorable conditions. Thus, there 
is no current evidence that threats are working to threaten the species 
with endangerment and we cannot predict extinction at any point in time 
in the foreseeable future, regardless of whether the foreseeable future 
is defined as less than 100 years, 100 years, or more than 100 years.
    In summary, the Act requires us to make a decision based on the 
best available data at the time of the listing determination. 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 know that annual 
abundance is strongly correlated with spring precipitation (March-May) 
and a high degree of variability in annual abundance is therefore to be 
expected. The best available range-wide data indicate that abundance of 
the population range-wide is strongly correlated with precipitation and 
has increased in recent years in association with increased rainfall, 
as expected.
    Accordingly based solely on the best available data, we find that 
Lepidium papilliferum is not presently in danger of extinction 
throughout all or a significant portion of its range nor is it likely 
to become an endangered species throughout all or a significant portion 
of its range in the foreseeable future.

References Cited

    A complete list of all references cited herein, as well as others, 
is available upon request from our Snake River Basin Office (see 
ADDRESSES section).

Author(s)

    The primary authors of this final rule are staff of the U.S. Fish 
and Wildlife Service.

    Authority: 16 U.S.C. 1531 et seq.

    Dated January 4, 2007.
H. Dale Hall,
Director, U.S. Fish and Wildlife Service.
[FR Doc. 07-60 Filed 1-11-07; 8:45 am]
 BILLING CODE 4310-55-P