introduction - Pennsylvania Natural Heritage Program

(Gaultheria hispidula), and two species of screwstem (Bartonia paniculata and Bartonia virginica)are also found.Central Wetland Core Habitat Area—The hemlock palustrine forest wetland along the middletributary to Twelvemile Run is much less extensive; it consists of a broad, seasonally saturated areadominated by cinnamon- or interrupted- fern (Osmunda sp.) tussocks.West Wetland Core Habitat Area—The wetland along the westernmost tributary to Twelvemile Runappears to have resulted from beaver activity. Active dams are present along the tributary, as well aspreviously dammed areas that now contain mud flats, meadows, and shrub thickets in various degreesof succession. Species included: steeblebush (Spiraea tomentosa), lowbush blueberry (Vacciniumangustifolium), sedges (Carex gynandra, Carex intumescens, Carex folliculata, Carex lurida), burreed(Sparganium chlorocarpum), marsh St. Johns’-wort (Triadenum sp.), cranberry (Vacciniummacrocarpon), needle-and-thread grass (Brachyelytrum erectum), lady’s tresses (Spiranthes cernua),soft rush (Juncus effusus), fowl manna-grass (Glyceria americana), smooth blue aster (Aster laevis),wrinkle-leaf goldenrod (Solidago rugosa), and other goldenrods (Solidago spp.).None of these wetlands have been surveyed to document animal inhabitants. All three are potentialhabitat for amphibians and aquatic or semi-aquatic insects such as dragonflies and damselflies, andmuch of the biodiversity of wetlands often consists of these taxa. Some of these species primarilyinhabit wetlands, while others also depend on upland areas surrounding a wetland for habitat. Foramphibian and aquatic reptile species expected in this region of Pennsylvania, habitats with openwater may host several of the more mobile species with migration distances averaging ~400 m, whilespecies typical of habitats without open water have migration distances that average 50 m or less(Semlitsch and Bodie 2003).Supporting Natural Landscape—The upland forest surrounding the wetlands is an oak-heathcommunity with red maple mixed in the canopy, generally with little plant diversity in the understory.The herbaceous layer is generally dominated by bracken fern (Pteridium aquilinum) and heath species(Vaccinium angustifolium, Gaultheria procumbens); the lack of regeneration or shrubs and the lowspecies diversity may be indicative of persistent overbrowsing. Some areas in the watershed havebeen timbered more recently and now contain young sapling regrowth.Threats and StressesCore Habitat Areas—In the core areas, any forest canopy removal in the forest surrounding thewetlands could impact the quality of the habitat for amphibians. Canopy removal in the vicinity of awetland will raise the temperatures in the wetland, potentially altering its habitat quality and speciescomposition. In the East Wetland this could negatively impact the creeping snowberry population, asthis species is adapted to more northern climates. Direct disturbances in the wetland area of anygreater intensity than occasional foot traffic will damage the habitat.Supporting Natural Landscape—Use of chemical weed and pest controls within the watershed of thewetlands may harm wetland flora and fauna. Timber removal and road construction or other removalof vegetative cover will increase sediment loads in runoff, which degrades water quality and canimpair the capacity of the wetland habitat to support pollution-sensitive species. Mining or otherextensive bedrock disturbances have the potential to create pollution that permanently and severelydegrades water quality.RecommendationsCore Habitat Areas—Within the wetlands themselves, activities of greater intensity than occasionalfoot traffic should be avoided due to the sensitivity of the habitat. Forest canopy removal operations73