Vegetation classification and mapping at Thomas Stone National Historic Site, Maryland

Lea, Chris; Sneddon, Lesley; Eastman, Elizabeth

Vegetation classification and mapping of Thomas Stone National Historic Site follows the guidelines developed for the U.S. National Vegetation Classification (USNVC). An initial site visit was conducted to observe and record the range of compositional and environmental variation within the park. These data were then used to identify representative stands where twenty-three vegetation plots were sampled. Vegetation plots included quantitative and qualitative data on vegetation composition and structure as well as environmental characteristics. Plot data collected at Thomas Stone National Historic Site were added to a larger data set collected at nearby National Park System units of the National Capital Region and analyzed using an array of multivariate techniques to produce the vegetation classification. Twelve USNVC associations and three land use categories are described for the lands within and adjacent to Thomas Stone National Historic Site. The upland areas are characterized by Dry Mesic Forest, Oak – Heath Forest, and three successional hardwood forest types, including Sweetgum Forest, Early Successional Mesic Forest, and a Pine - Oak successional type dominated by Virginia pine (Pinus virginiana). Wetland forests are characterized by a locallydefined Depositional Bar association dominated by river birch (Betula nigra) occurring on rocky bars in and along streams, a Floodplain Forest dominated by tuliptree (Liriodendron tulipifera) and sweetgum (Liquidambar styraciflua) at stream edges, and two red maple (Acer rubrum) types, one type in basin depressions (Upland Depression Swamp) and the other in seasonally flooded areas (Seepage Swamp). Non-forested types include a seasonally flooded herbaceous marsh (Woolgrass Marsh), as well as two cultural/human altered herbaceous types: Dry Meadow, dominated by fescue, and Wet Meadow, a locally defined deer-tongue grass type which was observed along powerline rights-of-way and road sides just outside the park boundary. Ten and nine of the USNVC types were mapped as individual polygons within the project area and the park, respectively. Two of the types were present in too small of an area to be mapped.. Areas that could not be readily mapped to USNVC associations were assigned to mosaic or unvegetated cover classes as appropriate. Detailed descriptions of the local and global expressions of each vegetation type, a field key to vegetation types, a plant species list derived from the plot samples, and an index to photographic documentation are included as appendixes.

Vegetation classification and mapping at Thomas Stone National Historic Site, Maryland

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