[From the U.S. Government Printing Office, www.gpo.gov]










                                     NA90AA-D-CZ795


                                         Task 8



                   @<ASSESSMENT OF THE ENCROACHMENT OF WOODY VEGETATION
              INTO FIVE UNFORESTED DELMARVA BAYS AND FIVE COASTAL PLAIN BOGS


                             BY ANALYSIS OF AERIAL PHOTOGRAPHY











                                     Submitted to the
                                 Coa@;tal Resources Division
                                 Tidewater Administration
 NI&



                                          by the
                             Maryland Natural Heritage Program
                               Resource Conservation Service





                                       Prepared by:

                                   Katharine A. McCarthy
                                     Judith R. Modlin







                                        April 1992












                                     INTRODUCTION



               Delmarva bays and bogs are the most significant nontidal
          wetland habitats for rare plant species on Maryland's Coastal
          Plain. These two habitattypes harbor more rare species than all
          other nontidal wetland types of coastal Maryland. In both bays
          and bogs, the majority of rare species occur within non-forested,
          herbaceous openings,.. Bogs also characteristically support low
          shrubs scattered throughout the herbaceous openings. Field
          observations by local naturalists and Natural Heritage Program
          Staff in the 1980s indicated that saplings and tall shrubs were
          encroaching on these openings and may threaten the rare, shade-
          intolerant, herbaceous species. To address this concern, this
          study was undertaken to determine,the extent of change in size of
          herbaceous openings for five bays and f 'ive bogs known to harbor
          high concentrations of rare species (Appendix I). Vegetation
          cover was assessed from aerial photographs dating from the 1930s
          to the 1980s.

               The results of the analysis of woody plant succession in
          bogs will assist in determining which bogs-are to be studied in
          further detail in the field beginning in summer 1992. Knowledge
          gained from the field study and the study of historical change in
          bog size will be incorporated in the development of management
          plans for selected.bogs.

               As with all wetlands, hydrology influences the composition
          of vegetation in Delmarva bays-. The duration of flooding appears
          to be the major influence limiting the establishment of trees in
          the herbaceous openings of Delmarva bays. Fire and grazing have
          been suggested as historical influences limiting woody
          encroachment; however, data has not substantiated these theories
          for Maryland's bays. Maintenance of the hydrologic regime
          therefore appears essential to the maintenance of the herbaceous
          openings that support rare plant species. Because land use
          practices influence hydrology, we initiated a study of
          surrounding land use in conjunction with the assessment of change
          in size of herbaceous openings for five Delmarva bays.











                                       METHODS



               A set of three historical aerial photographs was'obtained
          for all Coastal Plain bogs and Delmarva bays that are listed as
          Geographical Areas of Particular Concern (GAPC's) in Maryland.
          The earliest available aerial photograph for each site (1930s-
          1940s) was obtained to serve as a baseline against which to
          compare vegetation changes in later photographs. These early
          photographs were U.S. Soil Conservation Service photos obtained
          in person fromthe National Archives and Records Administration
          in Alexandria, Virginia. We reviewed photographic reels,
          selecting the frame that offered the best resolution for each bay
          or bog.

               The most recent aerial photography available commercially
          was generally at too small a scale to adequately resolve
          differences in vegetation type. Therefore we used the most
          recent photographs flown at an appropriate scale (1:24,000 or
          larger). These photographs were flown primarily in 1985 and were
          available in-house from the Water Resources Administration or the
          Natural Heritage Program (both Maryland Department of Natural
          Resources). A third set of photos of intermediate date (1957 -
          1958) and appropriate scale, flown by SCS, were obtained by mail
          from the U.S. Department of Agriculture, Agricultural ,
          .Stabilization and Conservation Service in Utah. For two sites,
          additional, larger-scale historical photographs were available
          from Anne Arundel County. These were used to better understand
          and describe the vegetation history at those sites, but were
          omitted from the analysis of changes in area because large
          differences in scale made it hard to consistently interpret
          vegetation changes.

               Based on the quality of available photos, site protection
          priorities, ownership patterns, and geographical distribution,
          five bays and five bogs were selected for analysis (Table I).
          Each photo was scanned using the Map and Image Processing system
          software (MIPS, by MicroImages, Inc., Lincoln, Nebraska, version
          3.x). Scanning was done at 400 dpi using aHowtek
          Scanmaster 3, Hewlett-Packard (HP) Vectra 486/25T personal
          computer, an HP 1611 high-resolution UGA color monitor with
          Metheus 1228 UGA graphics board, and an HP VGA color monitor for
          text. The images were stored on optical disk using a Relax MO
          Plus, 600 MB Optical Drive.

               Each photograph was examined under magnification to
          determine the boundary between the herbaceous opening and woody
          cover (bays) or between herbaceous/low shrub cover and tall woody
          cover (bogs). Open water was included in the measurement of
          herbaceous openings because it fluctuates seasonally and areas
          covered.by open water in one season may support bay or bog


                                          2









          vegetation'observable at another time of year. The area of the
          opening was calculated for each site in each year using the'MIPS
          "planimeter" program. In order to assess the reliability of the
          results, each measurement was repeated a minimum of four times
          and the mean area was calculated. For each site, the
          significance of differences among mean areas in different years
          was assessed using the student's t-test.

               We noted that the stated scale of the photographs was not
          always accurate. To correct for minor scale inconsistencies or
          image distortion, each bog photograph was calibrated by using the
          MIPS "calipers" program to measure the distance@between two
          landmarks near the bog and common to all three photos.
          Differences in the measured distance were used to produce an area
          calibration factor for each photo, and area calculations were
          corrected accordingly. For bay sites, each photograph was
          registered against registered Land Sat spot imagery prior to
          analysis of surrounding land use patterns. Photo registration
          assisted in correcting for scale discrepancies and photo
          distortion.

               Surrounding land use was analyzed for-the five Delmarva bays
          at intervals of 30m, 60m, 100m, and 300m from the edge of the
          herbaceous opening outlined in the earliest available photo
          (1930s). For consistency, the 1930s herbaceous opening was used
          as the basis for these interval measurements for the 1950s and
          1985 photos as well. The "vector buffer" function of MIPS was
          used to create polygons at these intervals around the herbaceous
          opening. Prints showing these polygons for Dorchester Pond were
          produced using an HP Paintjet XL printer and are included as
          Appendix II.

               Within each distance interval, area was measured for the
          following classes of land use: cultivated fields, old fields,
          forest, and recently logged. Area was calculated with the MIPS
          "planimeter" function. The length of roads and ditches occurring
          within each interval was measured with the MIPS "calipers"
          function. The number of buildings present was recorded for each
          interval.


















                                          3'












                                       RESULTS



          Coastal Plain Bogs

               The size of herbaceous/low shrub openings at all bog sites
          declined significantly (P < .005)between the 1930's or 40's and
          the 1980's (Tables II and III). The greatest proportional
          decrease in size occurred at Suitland Bog, where the size of the
          opening in 1981 was only 6% of its size in 1937 (Table IV), an
          average rate of decline of 2.1% per year. The opening at
          Suitland Bog was the largest of all sites studied in the 1930's
          and 1940's (4.1 ha in 1937) but the second smallest by the 1980's
          (0.26 ha in 1981).. Most of the loss occurred between 1937 and
          1957, when opening size decreased by 81%.

               The next largest proportional declines in opening size
          occurred at the two Eastern Shore sites. At Horsebridge Creek
          Bog in 1985 the opening had decreased to 24% of its 1938 size-
          (1.6% decline per year). The total opening at Sharptown Bog had
          declined in 1985 to 31% of its 1938 size (1.5% per year). The
          real loss of bog vegetation at these two sites was probably even
          greater. At Horsebridge Creek Bog in 1938, a wide, herbaceous
          wetland opening surrounded both sides of Horsebridge Creek for
          more than 1/4 mile of its length. Between 1958 and 1985, the
          creek was channelized and a powerline right-of-way constructed
          across it; the only openings remaining in 1985 were the narrow
          stream channel and the artificially maintained right-of-way where
          the powerline crossed the bog. Most of this opening would not
          have been wet enough to support bog vegetation. All rare species
          reported in mid-1980's field surveys at this site were confined
          to two small boggy depressions under the powerline.

               Sharptown Bog was already traversed by a powerline in 1938,
          but the right-of-way had not been recently cleared and most of
          the 0.5 ha opening measured-in that year appeared to be a natural
          herbaceous opening along a stream. By 1958, the powerline right-
          of-way was cleared and the streamside opening was beginning to
          close in with woody vegetation. By 1985, the entire streamside
          opening outside of the powerline right-of-way had become
          forested.


               Patterns of vegetation change were observed more closely at
          the two Anne Arundel County bogs due to the availability of
          large-scale photographs from intermediate years. -In 1943,
          Gumbottom Wetland contained an apparently all-herbaceous opening
          of approximately .5 ha, clearly distinct from a very large
          adjacent shrub swamp. By 1952 and 1957 the.distinction was less.
          clear, as shrubs had begun to move into the herbaceous opening.
          By 1970, much of the opening was dominated by low shrubs, but it
          was still distinct from the taller shrub canopy of the shrub
          swamp. By 1984 and 1985,.the size of the opening had decreased

                                          4









          to less than 1/3 hectare (.28 ha in 1985), and tall shrubs had
          penetrated into the interior of theopening in some locations.
          Gumbottom Wetland showed the lowest proportional decline in area
          of opening among the bog sites. In 1985, the size of the opening
          was 53% of its 1943 size. The decrease occurred much more
          rapidly between 1943 and 1957 (2.3% per year) than between 1957
          and 1985 (0.5% per year).

               North Gray's Bog had  the largest herbaceous/shrub opening in
          1985, with an area of 1.1  ha. Although it is known from field
          surveys that part of this  opening is composed of an open water
          pond and emergent marsh, this portion is important because it
          represents area forpotential bog expansion. This is the only
          site studied where the bog appears to be in the early stages of
          formation, with a thick peat mat gradually growing gradually out
          over the still water. North Gray's Bog showed the second lowest'
          proportional decline in area, decreasing to 42% of its 1948 size
          by 1985. It was the only site in which the greater decline
          occurred between the 1950's and the 1980's (2.1% decline per
          year).@ The area of the opening at this site stayed the same
          between 1948 and 1957. Intermediate photos indicate that the
          decline had begun by 1970, when a tall shrub canopy had begun   to
          penetrate the opening in the drier, eastern end of the site.


         ,Delmarva Bays

          Change in Area of Herbaceous Opening


               The area of herbaceous openings declined significantly
          (P < 0.01) from the 1930s through 1985 for all five bays studied
          (see Tables V and VI). For all sites, the-herbaceous openings
          consistently decreased in area from the 1930s to the 1950s and
          from the 1950s to the 1980s with one exception. Bridgetown Pond
          increased in area from 1958 to 1985; however, the herbaceous
          opening was significantly smaller in 1985 than it was in 1937 as
          a result of the significant decrease in area from 1937 to 1958.

               The largest proportional decrease in size of herbaceous
          opening occurred at Jackson Lane. The mean area of the opening
          in 1985 was 29% of the mean area in-1937. By 1985, the
          herbaceous opening at Golts Pond had decreased to 55% of its size
          in 1@37. By 19Z5 Black.Bottom Pond had decreased to 73% of its
          area in 1936. The smallest decreases in area of herbaceous
          opening were recorded for Bridgetown Pond and Dorchester Pond.
          By 1985, both of these sites declined to 91% of the areas
          recorded for 1937 and 1938 respectively.

               The decrease in area of herbac eous opening was larger from
          the 1930s to 1950s than in the subsequent period ending in 1985
          for all sites with the exception of Dorchester Pond.

                                           5













          Land Use Analysis

               .Two. of the five sites, Black Bottom Pond and Bridgetown
          Pond, experienced little change in land use from the 1930s to
          1985 (Table VII). Over 80% of the surrounding land remained
          forested within loom of the bays throughout the study period.
          Virtually no disturbance was evident within 60m of these bays
          during this period. of the four relatively small bays, Black
          Bottom and Bridgetown also experienced the least encroachment of
          woody species during the study period.

               The general trend in land usage observed from.the 1930s to
          1985 was of farm fields reverting to forest. At Dorchester Pond,
          Golts Pond, and Jackson Lane, 1/3 to 1/2 of the   land within loom
          of the bays was farmed in the 1930s. By 1985 all but 5% of this
          land had reverted to forest. In general, as fields reverted to
          forest, roads were abandoned so the length of roads present in
          all intervals generally declined during the study period. T   'he
          exceptions to this were at Golts Pond and Dorchester Pond.
          Numerous residences occur within 300m of Golts Pond and a few new
          roads were constructed to increase access to these properties.
          At Dorchester Pond, as fields were abandoned, roads were
          maintained at the field edges to provide access to nearby fields
          that remained in cultivation. This gave the appearance of an
          increase in road length in the.60-100m interval.

               No major ditches lie within 300m of the five bays studied.
          Field surveys revealed that small ditches are present at most of
          these bays, however, they are not visible in the aerial
          photographs. The forest-canopy conceals these ditches, so this
          is not an effective method to evaluate the position and effect of
          ditches.

               Logging was evident at both Dorchester Pond and Bridgetown
          Pond. At Dorchester, logging occurred in the 1930s in all
          intervals studied and beyond 300m to the south of the bay. At
          Bridgetown Pond, young irregular stands of pine along sand roads
          in the 1937 photo suggest that logging had recently occurred in
          the 100-300m interval. Areas of relatively open canopy in the
          1958 photo suggest that logging occurred again in the 100-300m
          interval.

            I New powerlines were constructed between 1957 and 1985
          crossing the 100-300m intervals at Golts Pond and Black Bottom
          Pond. Of the five bays studied, only Golts Pond had more than
          two buildings present within 300m of the bay. The bays occur in
          rural areas where lots tend to be large and houses widely
          dispersed. However Golts Pond lies near a small t   'own center. In
          1936, 24 buildings were located within 300m of the bay. Half of
          these were abandoned and by 1985 just 11 buildings.remained.

                                           6












                                      DISCUSSION



          Coastal Plain Bogs

               The encroachment of woody species into Coastal Plain bogs is
          a natural process of vegetation succession in which unforested
          bogs slowly become dominated by trees. Historically, new,sites
          developed that were suitable for colonization by shade intolerant
          bog vegetation, such as the edges of beaver ponds, old stream
          meanders, and openings in swamps created by fire during dry
          years., Today, a large portion of the landscape has been
          converted to residential, industrial, commercial, or agricultural
          uses, and most of Maryland's Coastal Plain bogs, many of which
          were located in counties now heavily urbanized, have been
          destroyed. Potential sites for new bog formation have also been
          destroyed, and the disturbances which created them, such as fire
          and flooding, have been suppressed. Because the natural
          development of new sites for bog formation can no longer keep
          pace with the accelerated loss of Maryland's few remaining bogs,
          the natural succession of woody species into those bogs threatens
          the survival of this unusual habitat. If unique Coastal Plain
          bog plant communities are to survive, active management to
          curtail woody encroachment into bogs may be required at some
          sites.

               Potential methods of woody species control include
          prescribed burns, flooding by blocking drainage ditches or
          reconstructing old dams, selective herbicide use, and removing
          tree saplings by hand. Each method has advantages and drawbacks.
          Burning and flooding may best mimic natural disturbances that
          maintained bog openings, but fire may not be feasible in
         .urban/suburban landscapes and flooding may-have direct,negative
          impacts on existing rare species. Herbicide use would have to be
          planned and executed with extreme caution to avoid damaging rare
          species or contaminating water or soil. Hand removal may be the
          most prudent and conservative choice, but even this choice
          requires caution and careful timing of work to minimize trampling
          fragile bog habitats. Decisions regarding vegetation management
          should be made after on-site research to evaluate such factors as
          the rate of woody encroachment into the bog, surrounding land
          use, and hydrology.

               The Maryland Natural Heritage Program has contracted to
          establish permanent plots at two bogs to measure the rate of tree.
          sapling encroachment over time and to provide management plans to
          control woody invasion at these sites. Together with a knowledge
          of ownership patterns and management history, the analyses of
          historical aerial photos provided information useful in
          determining which sites can profit most from on-site evaluation
          and control of woody encroachment.


                                          7









               Of the five bogs examined, Suitland Bog exhibited the
          highest rate of decline in size of opening. However, it may be
          least in need of intervention by the Natural Heritage Program
          because the site is owned and managed by the Maryland-National
          Capital Park and Planning Commission, which is actively working
          to protect it. The site's hydrology has been studied and the
          aquifer that feeds it has been purchased to protect the source of
          water. Berms, a boardwalk and a chain link fence around the
          major bog opening have been constructed to curtail erosion,
          trampling and dirt bike use. Efforts are underway by park staff
          to educate the public and to control woody encroachment manually.
          Thus Suitland Bog already receives the greatest degree of
          protection and management of any of the.five sites studied.

               Since the only openings remaining at Sharptown Bog and
          Horsebridge Creek Bog are within powerline rights-of-way, power
          company officials have instituted their own programs to control
          woody encroachment. At these sites, the Natural Heritage
          Progr,am's most profitable role will be maintaining continued
          landowner contact, particularly continued involvement in the
          development of management plans for the sites. We have provided
          the owners with maps and rare species reports and they have
          agreed to omit the bogs from broadcast herbicide application.
          Continued contact is essential to ensure that this agreement is
          followed. We also need to work with adjacent owners to preserve
          a forested buffer and to avoid repetition of the disastrous
          dragging of timber through the powerline opening that destroyed
          much of Sharptown Bog in the 1980s. At both Sharptown and
          Horsebridge Creek Bogs, monitoring of rare species and of exotic
          species is needed.

               The two sites with the greatest potential to benefit from
          tracking the encroachment of woody species and developing
          vegetation management plans are Gumbottom Wetland and North
          Gray's Bog. These sites currently support the largest herbaceous
          openings and they experienced the smallest decrease in area over
          the study period. (The total opening at Horsebridge Creek is
          larger.than at Gumbottom, but only'a small portion of it supports
          bog vegetation.) They have the largest forested buffers,- the
          least deleterious land use in the immediate vicinity and probably
          the lowest rate.of invasion by non-native, weedy species.
          Permission to study and eventually manage both sites, if needed,
          should be easier to obtain at thesetwo sites than at most bogs.
          Gumbottom Wetland is owned by the Maryland Department of Natural
          Resources. The homeowner's association that owns North Grayls
          Bog has registered the bog and its buffer, encouraged--scientific
          research by the Natural Heritage Program, and requested that
          Natural Heritage develop a management plan for the,site. Lastly,
          woody vegetation that is likely to eventually threaten bog
          species has been observed on site at both Gumbottom and North
          Gray's Bog,.so both sites would benefit from the monitoring and
          control of woody encroachment.

                                           8










          Delmarva Bays

               The two bays experiencing the greatest decr 'ease in size of
          herbaceous opening, Golts Pond and Jackson Lane, were both nearly
          surrounded by agricultural fields in the 1930's that reverted to
          forest by the 1950s. This suggests that agricultural activity
          may have contributed to maintaining the herbaceous opening at
          these sites. For example,,these areas may have been maintained
          for grazing. It is also possible that the decrease in the
          herbaceous openings is associated with natural succession of the
          abandoned agricultural fields. Evapotranspiration is
          particularly high in the early years of succession*when young
          trees of colonizing species grow most rapidly. This high rate of
          evapotranspiration may have reduced the water available to the
          bays and shortened the duration of flooding along the bay
          perimeter. With less flooding, woody species would establish
          more readily. This scenario is further supported by the slower
          decrease in size of herbaceous opening that occurred from the
          1950s to 1985, when both the growth rate and evaporatranspiration
          of the young forest would have slowed.

               Of the five bays, Dorchester Pond was-the exception in
          experiencing a more rapid decrease in the herbaceous opening from
          the 1950s to 1985 despite extensive logging in the 1930s and its
          proximity to reverting agricultural fields. According to recent
          findings of the U.S. Geological Survey (Pat Phillips, personal
          communication), the four smaller bays in Caroline and Kent
          Counties lie in the same hydrogeologic region, meaning they share
          similar patterns of groundwater and surface water movement due to
          similarities in elevational gradient, soil type, and geology.
          However, Dorchester Pond is in a different region with different
          hydrological characteristics and therefore may respond
          differently to changes in land use. It may-also be of
          significance that a large portion of forested land within loom of
          Dorchester Pond was converted to pine plantation between the
          1950s and 1985. 'These evergreens have a higher total annual
          transpiration rate than deciduous trees. The presence of a high
          density of pine close to the bay may reduce the available water
          and thus shorten the duration of flooding in the bay and promote
          woody succession.along the bay perimeter.

               Field observations indicate that the slight increase in size
          of the herbaceous opening at Bridgetown Pond may be the result of
          oaks dying from gypsy moth defoliation,

               Additional bays must be studied so that the sample size is
          larger in order to develop conclusive evidence of the effects of
          land use practices on Delmarva bays. However, the results of
          this study suggest that maintenance of mature, natural forest
          cover, especially within loom of a bay, may contribute to
          maintaining the herbaceous openings and the rare species they
          harbors.


                                          9









               The bays experiencing the most rapid decrease in size of
          herbaceous opening, Jackson Lane and Golts Pond should be
          carefully monitored to determine the status of rare species
          populations. While monitoring of plant communities is underway
          at Jackson Lane, there has been no effort to monitor the rare
          plant populations at either site. Removal of woody vegetation
          from the Jackson Lane bay should be seriously considered. At the
          present rate of succession, this bay will be completely forested
          in 30 years. It is likely that the rare species would be lost
          much sooner as they are gradually shaded.

               It is likely that land use activities be yond 300m from the
          bays influence the flora of the bays. For example, large tax
          ditches may draw down water over 1000 ft from the ditch. In
          addition, this study of aerial photographs proved ineffective in
          locating ditches. Information concerning the location and time
          of construction of ditches should be sought from the Soil
          Conservation Service. If 6ossible, this information should'be
          mapped and included in further analyses of land use around
          Delmarva bays. Further analyses should explore land use up to
          600m from bays and should include at least 20 bays to obtain more
          conclusive results.,































                                         10










                     Table 1. Inventory of aerial photography used to assess size of herbaceous/shrub opening.


                     Le
                        gend for photographic sources: AACo = Anne Arundel County Planning and Zoning Department; hMNUP
                     Maryland Natural Heritage Program, Departmeni of Natural Resources; SCS = U.S. Soil Conservation Service; WRA
                                                 C       C,
                        Water Resources Administration, Maryland Department of Natural Resources.



                     A. COASTAL PIAIN BOGS


                                          Site                                                 Year                 Source               Scale


                     Gumbottom Wetiand
                                Anne Arundel County
                                          USGS Quad: Round Bay                                 1943                 SCS                  1:20,000
                                                                                               1952                 AACo                 1:48001
                                                                                               1957                 SCS                  1:20,000
                                                                                               1970                 AACo                 1:12,0001
                                                                                               1984                 AACo                 1:24001
                                                                                               1985                 WRA                  1:12,000

                     Horsebridge Creek Bog
                                Wicomico County
                                          USGS Quad: Wango
                                                                                               1938                 SCS                  1:20,000
                                                                                               1958                 SCS                  1:20,000
                                                                                               1985                 WRA                  1:12,000

                     North Gray's Bog
                                Anne Arundel County
                                          USGS Quad: Gibson Island
                                                                                               1948                 SCS                  1:20,000
                                                                                               1952                 AACo(SCS)            1:48001
                                                                                               1957                 SCS                  -1:20,000
                                                                                               1970                 AACo                 1:12,0001
                                                                                               1984                 AACo                 1:24001
                                                                                               1985                 WRA                  1:12,000

                     Sharptown Bog
                                Wicomico County
                                          USGS Quads: Hebron, Sharptown
                                                                                               1938                 SCS                  1:20,000
                                                                                               1958                 SCS                  1:20,000
                                                                                               1985                 WRA                  1-12000


                     Suitland Bog
                                Prince George's County
                                             C,
                                          USGS Quad: Anacostia
                                                                                               1937                 SCS                  1:20,000
                                                                                               1957                 SCS                  1:20,000
                                                                                               1981                 MNHP                 1:24,000



                       Used to assist in interpretation of the three primary photos; area calculaiions were not based on these photos.












                    B. DELMARVA BAYS



                                       Site                                            Year               Source              Scale


                    Black Bottom Pond
                             Kent County
                                       USGS Quad.       Millington

                                                                                       1936               SCS                 1:20,000
                                                                                       1957               SCS                 1:20,000
                                                                                       1985               WRA                 1:12,000

                    Bridgetown Pond
                             Caroline County
                                       USGS Quad: Goldsboro


                                                                                       1937               SCS                 1:20,000
                                                                                       1958               SCS                 J:20,000
                                                                                       1985               WRA                 1:12,000


                    Dorchester Pond
                             Dorchester County
                                       USGS Quad: East New Market


                                                                                       1938               SCS                 1:20,000
                                                                                       1958               SCS                 1:20,000
                                                                                       1985               WRA                 1:12,000


                    Golts Pond
                             Kent County
                                       USGS Quad: Millington

                                                                                       1936               SCS                 1:20,000
                                                                                       1957               SCS                 1:20,000
                                                                                       1985               WRA                 1:12,000


                    Jackson Lane
                             Caroline County
                                       USGS Quad: Goldsboro


                                                                                       1937               SCS                 1:20,000
                                                                                       1958               SCS                 1:20,000
                                                                                       1985               WRA                 1:12,000



















                                                                                 12










                   TABLE 11. Area of herbaceous and/or low shrub opening in each Coastal Plain bog site for each year, reported as
                                                                                0
                   mean + standard error of repeated measurements. Means for a site with the same superscript are not statistically
                   different according to Students two-sample t-test values in Table IV.


                                                                                                   AREA OF OPENING (hectares)

                   SITE                                   MOfYR                              MEAN                  STANDARD ERROR


                   Gumbottom Wetland                      4/1943                             0.527a       +                  0.067
                                                          8/1957                             0.362b       +                  0.060
                                                                                             0.280c       +                  0.051


                   Horsebridge Creek Bog                  6/1938                             2.800a       +                  0.161
                                                          6/1958                             0.497b       +                  0.070
                                                          9/19851                            0.678c       +                  0.098

                   North Gray's Bog                       12/1948                            2.592a       +                  0.117
                                                          7/1957                             2.596a       +                  0.158
                                                          9/1985                             1.090b       +                  0.054

                   Suitlarid Bog                          5/1937                             4.148a       +                  0.155
                                                          6/1957                             0.800b       +                  0.070
                                                          4/1981                             0.257c       +                  0.035


                   Sharptown   Bog
                             Natural Herbaceous Wetland Opening

                                                          5/1938                           0.491a         +                  0.078
                                                          7/1958                           0. 176b        +                  0.050
                                                          9/1985                           0C

                             Opening Under    Powerline   Right-of-way

                                                          5/1938                           0.030a         +                  0.028
                                                          7/1958                           0.171b         +                  0.044
                                                          9/1985                           0. 164b        +                  0.040

                             Total Opening2

                                                          5/1938                           0.521
                                                          7/1958                           0.347
                                                          9/1985                           0.164




                   'The stream at this site had been channelized by 1985. The only openinog remaining is that maintained artificially for a
                   powerline right-of-way; most of opening is probably not wettand, and thus is incapable of supporting bog vegetation.

                   2Total area of opening at Sharptown Bog is not a mean but rather the sum of means of two @omponent
                   measurements; thus no standard error is given.










                                                                                13










                    Table M. Student's two-sample t-test for comparisons of mean area of herbaceous openings between years at                Coastal
                    Plain Bogs.           p, < 0.005. No asterisk indicates means are not statistically different.


                    Site                Years Compared df             Common Variance               t Value

                    Gumbottorn          1943 & 1957          8        0.020,                        12.89***
                      Wettand           1957  &  1985        8        0.016                         8.25***


                    Horsebridge         1958  &  1985        13       0.019                     -16.45***
                      Creek Bog         1938  &  1985        7        0.102                         80.60*

                    North Gray's        1948  &  1957        7        0.100                       0.07
                      Bog               1948  &  1985        6        0.037                         56.66***

                    Suitland Bog        1937  &  1957        6        0.070                         67.62***
                                        1957  &  1981        7        0.014                         59.95***


                    Sharptown Bog
                      Natural Opening

                                        1938 & 1958          t2       0.025                         21.03


                      Powerline Opening

                                        1938 & 19S8          7        0.008                         -27.43
                                        1958 & 1985          9        0.009                          1.24
                                        1938 & 1985          8        0.007                         -28.55***











































                                                                                  14










                  TABLE IV. Percentage of historical opening remaining open, as compared to the size of the opening in the earliest
                  year examined.

                  SITE                       YEAR                       PROPORTION OF HISTORICAL
                                                                        OPENING REMAINING OPEN



                  Gumbottom Wetland


                                             1943                                  100%
                                             1957                                  67%
                                             1985                                  53%


                  Horsebridge Creek Bog
                                             1938                                  100%
                                             1958                                  18%
                                             1985                                  24%1


                  North Gray's Bog
                                             1948                                  100%
                                             1957                                  100%
                                             1985                                  42%


                  Suitland Bog
                                             1937                                  100%
                                             1957                                  19%
                                             1981                                  6%


                  Sharptown Bog
                           Natural Opening
                                             1938                                  100%
                                             1958                                  36%
                                             1985                                  0%


                           Opening Under Powerline Right-of-way
                                             1938                                  too%
                                             1958                                  585%
                                             1985                                  547%


                           Total Opening
                                             1938                                  100%
                                             1958                                  66%
                                             1985                                  31%



                  'Only opening remaining in 1985  was that maintained artificially for powerline right-of-way; most of opening was
                  probably not wedand and thus would not be expected to support bog vegetation.














                                                                           15










                                      Table V. Area of herbaceous opening for Delmarva bays as calculated from aerial photos.




                                                                      Mean Area                    Variance                   Standard
                     Site Name                       Mo[Yr               X (M2)                             S                 Error (SE)

                     Black Bottom Pond               8/36                1,054                              31                13
                                                     8/57                   761                             36                15
                                                     9/85                   766                             3                 1

                     Bridgetown Pond                 10/37               4,532                              83                34
                                                     5/58                3,905                              52                21
                                                     8/85                4,106                              64                26

                     Dorchester Pond                 5/38                64,972                             136               56
                                                     5/58                62,281                             239               98
                                                     9/85                58,755                             46                19

                     Golts Pond                      10/36               6,172                              102               42
                                                     8/57                4,551                              99                40
                                                     9/85                3,396                              83                34

                     Jackson Lane                    10/37               11,516                             96                39
                                                     5/58                5,247                              88                36
                                                     9/85                3,295                              32                13





                                    Table VI. Student's t test for difference between mean area of openings of Delmarva bays.
                                             Common df=10.



                                                       Years                    Common                                        Significant
                     Site Name                       Compared                  Variance                     T Value           difference p=0.01

                     Bridgetown Pond                 1937 & 1958                    76                      14.3              Yes
                                                     1958 &  1985                   64                      5.4               Yes
                                                     1937 &  1985                   81                      9.1               Yes


                     Black Bottom Pond               1936 &  1957                   37                      13.7              Yes
                                                     1957 &  1985                   28                      0.5               No


                     Dorchester Pond                 1938 &  1958                   213                     21.9              Yes
                                                     1958 &  1985                   188                     32.0              Yes

                     Golts Pond                      1936 &  1957                   110                     25.5              Yes
                                                     1957 &  1985                   too                     20.0              Yes

                     Jackson Lane                    1937 &  1958                   101                     108               Yes
                                                     1958 &  1985                   73                      46                Yes









                                                                                      16










                                  'rabic VIL          Land usacTe within four intervals of distance from the herbaceous openings of five Delmarva
                                                      bays. Proportion     of area within each interval for each land use is identified by percent area
                                                      in use within the    interval. 'rhe length (m) of     roads and ditches within each interval is
                                                      given.


                     BIACK BOTTOM POND
                                            Bay Edge-30m                   30-60m                           60-100m                       100-300m
                                            1936 1957 1985                 1936 1957 1985                   1936 1957 1985                1936 1957 1985
                     farmed                 --- ---   ---                  - --- --- ---                    --- ---       ---             11       10   14
                     oldfield               --- ---   ---                  5      --- ---                   9     --- ---                 8        5    ---
                     forested               100   100    too               95     100    100                91    100     too             80       85   81
                     powerline              --- ---   ---                  --- ---   ---                    --- ---       ---             --- ---       5
                     roads (m)              --- ---   ---                  -    --- ---                     --- ---       ---             --- ---       ---
                     ditches (m)            --- ---   ---                  - --- --- ---                    --- ---       ---             --- ---       ---

                     BRIDGETOWN POND
                                            Bay Edge-30m                   30-60m                           60-100m                       100-300m
                                            1937 1958 1985                 1937 1958 1985                   1937 1958 1985                1937     1958 1985
                     farmed                 --- ---   ---                  --- ---   ---                    6     6       ---             18       15   13
                     oldfield               --- ---   ---                  --- ---   ---                    12    --- ---                 18       1    ---
                     forested               too   too 160                  100    100 100                   82    94      100             61       75   83
                     roads (m)              --- ---   ---                  --- ---   ---                    --- ---       ---             694      430  ---
                     ditches (m)            --- ----  ---                  --- ---   ---                    --- ---       ---             159      173 105
                     other bays                       ---                  --- ---   ---                    --- ---       ---             3        4    4
                     logged                 --- ---   ---                  --- ---   ---                    --- ---       ---             ---      4    ---


                     DORCEMSTER POND
                                            Bay Edge-30m                   30-60m                           60-100m                       100-300m
                                            1938 1958 1985                 1938   1958 1985                 1938  1958 1985               1938     1958 1985
                     farmed                 --- ---   ---                  34     19     ---                29    21      2               36       22   17
                     logged                 8     --- ---                  49     --- ---                   27    --- ---                 17       --- ---
                     forested               92    100    100               17     81     100                43    79      98              48       78   83
                     roads (m)              --- ---   ---                  --- ---   244                    272   435     533             1437     1137 881
                     ditches (m)            --- ---   ---                  --- ---   ---                    --- ---       ---             --- ---       ---

                     GOLISPOND
                                            Bay Edge-30m                   30-60m                           60- 1 00m                     100-300m
                                            1936 1957 1985                 1936   1957 1985                 1936 -1957 1985               1936 1957 1985
                     farmed                 4     1      ---               35     30     3                  40    22      3               60       45   40
                     oldfield               96    --- ---                  51     --- ---                   39    ---     15              25       5    2
                     forested               ---  99      100               14     70     97                 21    78      82              5        55   55
                     *roads (m)             --- ---   ---                  26     26     ---                302   302 345                 2046 2046 2472
                     ditches (m)            --- ---   ---                  --- ---   ---                    --- ---       ---             --- --- - ---
                     powerline (%)          --- ---   ---                  --- ---   ---                    --- ---       ---             --- ---       3
                     *includes railroad


                     JACKSON LANE
                                            Bay Edge-30m.                  30-60rn                          60-100m                       100-300m
                                            1937 1958 1985                 1937 1958 1985                   1937 1958 1985                1937     1958 1985
                     farmed                 25    --- ---                  58     --- ---                   41    3       ---             30       5    ---
                     oldfield               --- ---   ---                  --- ---   ---                    --- 5         ---             7        15   ---
                     forested               75    100    100               42     100    100'               59    92      100             63       80   96
                     other bays             --- ---   ---           - --- --- ---                           --- --- ---                   4        4    4
                     roads (m)              --- ---   ---                  40     40     ---                ---  40       ---             1035 412      101
                     ditches (m)            --- ---   ---                  --- ---   ---                    --- --- ---                   --- ---       ---





                                                                                         17
























          APPENDIX I.   Rare species occurring at each Coastal Plain bog
                        and Delmarva bay site studied.











                                RARE SPECIES SUMMARY TABLE



           Site Name: Gumbottom.Wetland


           County: Anne Arundel

           USGS Quad: Round Bay


           Scientfic Name             Common Name               Status



           Carex exilis               Coast Sedge               Endangered

           Carex bullata              Button Sedge              Threatened

           Chamaedaphne calVculata    Leatherleaf               Threatened

           Platanthera ciliaris       Yellow-fringed Orchid-    Threatened

           Sarracenia Purpurea        Northern Pitcher Plant    Threatened

           Bartonia paniculata        Twining Bartonia          Watch List

           Carex atlantica            Eastern Sedge             Watch List'

           Drosera rotundifolia       Round-leaved Sundew       Watch List

           Eriophorum virginicum      Tawny Cottongrass         Watch List

           Rhynchospora alba          White Beakrush            Watch List

           Vaccinium macrocarpon      Large Cranberry           Watch List











                              RARE SPECIES SUMMARY TABLE



          SITE NAME: Horsebridge Creek Bog

          COUNTY: Wicomico


          USGS QUAD: Wango



          scientific name                Common name              Status


          Sclerolepis uniflora           Pink.Bog-button          Endangered

          Sarracenia purpurea            Northern Pitcher-plant   Threatened

          Sagittaria engelmanniana       Engelmann's Arrowhead    Threatened

          Eriocaulon compressum          Flattened Pipewort       Rare

          Drosera rotundifolia           Round-leaved Sundew      Watch List






          The following additional rare species were reported from this
          site in the early 1980's and may persist at the site:

          Amphicarpum purshii
          Bartonia paniculata
          Psilocarva scirpoides
          Utricularia fibrosa
          Xyris fimbriata
          Xyris smalliana











                              RARE SPECIES SUMMARY TABLE



           SITE NAME: North Gray's Bog

           COUNTY:   Anne Arundel


           USGS QUAD: Gibson Island


           Scientific name               Common name               Status

           Carex exilis                  Coast Sedge               Endangered

           Arundinaria gigantea          Giant Cane                Threatened

           Chamaedaphne calvculata       Leatherleaf               Threatened

           Eleocharis olivacea           Green Spikerush           Watch List

           Eriophorum virginicum         Tawny Cottongrass         Watch List

           Rhynchospora alba             White Beakrush            Watch List

           Vaccinium macrocarpon         Large Cranberry           Watch List











                              RARE SPECIES SUMMARY TABLE



          SITE NAME: Sharptown Bog

          COUNTY:   Wicomico


          USGS QUAD: Sharptown, Hebron


          Scientific name                Common name              Status

          Cleistes divaricata            Spreading Pogonia        Endangered

          Eleocharis robbinsii           Robbins' Spikerush       Endangered

          Fuirena pumila                 Smooth Fuirena           Endangered

          PolVgala cruciata              Cross-leaved Milkwort    Endangered

          Psilocarya nitens              Short-beaked Baldrush    Endangered

          Rhynchospora glomerata         Clustered Beakrush       Endangered

          Sciryus subterminalis          Water Clubrush           Endangered

          Sclerolepis uniflora           Pink Bog-button          Endangered

          Sarracenia purpurea            Northern Pitcher-plant   Threatened

          Drosera rotundifolia           Round-leaved Sundew      Watch List

          Pogonia ophioglossoides        Rose Pogonia             Watch List

          Utricularia radiata            Small Swollen            Watch List
                                              Bladderwort












                              RARE SPECIES SUMMARY TABLE



          SITE NAME: Suitland Bog

          COUNTY: Prince George's

          USGS QUAD: Anacostia


          Scientific name                Common name               Status

          Asclepias rubra                Red Milkweed              Endangered

          Polvqala cruciata              Cross-leaved Milkwort     Endangered

          Rhynchospora glomerata         Clustered Beakrush        Endangered

          Sarracenia purpurea            Northern Pitcher-plant    Threatened'

          Thelypteris simulata           Bog Fern                  Threatened

          Eleocharis tortilis            Twisted Spikerush         State Rare

          Eriocaulon decangulare         Ten-angled Pipewort       State Rare

          Aronia prunifolia -            Purple Chokeberry         Watch List

          Eriorhorum virginicum          Tawny Cottongrass         Watch List

          Melanthium virainicum          Virginia Bunchflower      Watch Li  st

          Pogonia ophioglossoides        Rose Pogonia              Watch List

          Quercus prinoides              Dwarf Chestnut Oak        Watch List

          Rhododendron atlanticum        Dwarf Azalea              Watch List

          Rhynchospora alba              White Beakrush            Watch List

          Senecio pauperculus            Balsam Ragwort            Watch List

          Utricularia subulata           Zig-zag Bladderwort       Watch List


          In addition, the following rare crustacean may occur here
          (because hybrids of this species with Stvqobromus tenuis [Watch
          List species] have been reported historically from "near
          Suitland"):

          .Stygobromus havi              Hay's Spring Amphipod     Federally
                                                                  Endangered










       4r,


                                RARE SPECIES SUMMARY TABLE



           SITE NAME: Black Bottom Pond


           COUNTY: Kent

           USGS QUAD: Millington


           Scientific name                 Common name                Status

           Bidens discoidea                Small Beggar-ticks         Endangered

           Carex gicrantea                 Giant Sedge                Endangered
           Fimbristylis ye@yusilla         Harper's Fimbristylis      Endangered

           Hottonia inflata                Featherfoil                Endangered

           Rhynchospora corniculata        Short-bristled             Endangered
                                                 Hornedrush


           Oldenlandia uniflora            Clustered Bluets           State Rare





           SITE NAME: Bridgetown Pond

           COUNTY: Caroline


           USGS QUAD: Goldsboro



           Scientific name                 Common name                Status

           Ambystoma tigrinum              Eastern Tiger Salamander   Endangered

           Hyla gratiosa                   Barking Treefrog           Endangered

           Psilocarva scirpo ides          Long-beaked Baldrush       Endangered

           Carex bullata                   Button Sedge               Threatened

           Sagitaria,engelmanniana         Engelmann's Arrowhead      Threatened'

           Scleria reticularis             'Reticulated Nutrush       Rare

           Rana virgatipes                 Carpenter Frog             In Need of
                                                                     Conservation


           Panicum hemitomon               Maidencane                 Watch List.











                              RARE SPECIES SUM14ARY TABLE



          SITE NAME: Dorchester Pond


          COUNTY: 'Dorchester


          USGS QUAD: East New Market


          scientific name                Common name              Status

          Eleocharis robbinsii           Robbins' Spikerush       Endangered
                                                        i
          Hypericum adpressum            Creeping'St. John's-     Endangered
                                              wort

          Lachnanthes caroliniana        Red-root                 Endangered

          Psilodarya scirpoides          Long-beaked Baldrush     Endangered

          Rhynchospora inundata          Drowned Hornedrush       Endangered

          xyris smalliana                Small's Yelloweyed-grass Endangered

          Utricularia purpurea           Purple Bladderwort       Threatened

          Podilymbus podiceps            Pied-bill Grebe          Rare

          Scleria reticularis            Reticulated Nutrush      Rare

          Rana virgitipes                Carpenter Frog           In,Need of
                                                                 Conservation











                               RARE SPECIES SUMMARY TABLE



          SITE NAME: Golts Pond


          COUNTY: Kent

          USGS QUAD: Millington


          Scientific name                 Common name               Status

          Carex gigantea                  Giant Sedge               Endangered

          Fimbristylis perpusilla         Harper's Fimbristylis     Endangered

          Bartonia paniculata             Twining Bartonia          Watch List








          SITE NAME: Jackson Lane


          COUNTY: Caroline


          USGS QUAD: Goldsboro



          @Scientific name                Common name               Status

          Fimbristylis perpusilla         Dwarf Fimbristylis        State
                                                                    Endangered;
                                                                    Federal
                                                                    Candidate (C-2)

          Eleocharis melanocarpa          Black-fruited             Endangered
                                          Spike-rush

          Hottonia inflata                Featherfoil               Endangered

          Panicum hemitomon               Maidencane                Watch List
























          APPENDIX II.   Dorchester Pond 1938 (a), 1958 (b), and 1985 (c)
                         aerial images produced by MIPS at approximate
                         scale 1:6000 with 1938 herbaceous opening, 60m,
                         100m, and 300m buffers shown in white.






















                                                                  .. .... .

































                                                                             ow,














                                                               'g
                                                                                tr-












             Appendix II a. Dorchester Pond 1938 aerial image. Approximate scalit 1:6000,
             with herbaceous opening, 60m, 100m, and 300m buffers in white.

















                                                                                  .l WRI
                                                                                                     _kR
                                                                                         WERE
                                                                                            ERM
                                                                                 WE




                                                            V-P.,






























                                                                                                                                 -.44



                                                                                                                         02.












                       Appendix II b. Dorchester Pond 1958 aerial image. Approximate scale 1:6000
                       with herbaceous opening, 60m, 100m, and 300m buffers in white.
































                                                                    owl*















































        Appendix II c. Dorchester Pond-1985 aerial image. Approximate scale 1:6000 with
        1938 herbaceous opening, 60P, 100m, and 300m buffers in white.







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