Wetlands is a common word, which is frequently used by the media, government and conservation groups. However, it is actually a broad term; multiple types of them exist. According to the EPA, they are defined as places with water covering the soil or being present at or near the surface both constantly and seasonally. These areas have common names, such as bogs, fens, marshes, and swamps, which derive from their characteristics and location. Specifically, the duration of the presence of water influences the flora and fauna communities in and around it. Longer periods of wetness allow for the development of aquatic soils and the growth of specially adapted plants. Overall, wetlands have multiple functions, including erosion control, flood protection, habitat for wildlife, and protection of water quality.
Seeps are one kind of wetland. Groundwater rises to the surface, but disperses through the soil before emerging through a distinct hole, which may be fissure or joint in solid rock or a small opening in porous ground. Its consistent flow maintains soil saturation; however, the source is not distinct nor does the water move as quickly as from a spring. This emergence forms a localized pool which is shallow and broad. Sometimes it appears as a small water hole or a wet spot. The water itself is clear, although it contains minerals obtained during its journey through the bedrock. These formations exist at the base of sloped areas, including glacial moraines (accumulated debris left behind by glaciers), hillsides and river banks.
The most unique features of this type of wetland are existing year round and maintaining a consistent temperature between 50-60 degrees Fahrenheit. In winter, this temperature will melt the snow and expose an area of food for wildlife, as well as providing water, particularly during winters with severe cold, when none is available for extended periods. Also, the seep serves as a method of travel for some animals and breeding habitat for amphibians and aquatic insects. Due to its temperature, spring vegetation emerges earlier than other areas, providing a critical food source when sustenance from the previous fall has been consumed. In addition, it creates habitat for animals and plants that cannot tolerate wetlands which experience seasonal fluctuations in water level.
Seeps are part of the palustrine plant community, a non-tidal wetland dominated by shrubs and trees, having four characteristics: no larger than 20 acres in size; no deeper in its deepest area than 2 meters; salinity less than 0.5% of ocean-derived salts; and no evidence of wave action or shoreline features, according to the United States Fish and Wildlife Service. Scientific surveys of these plant communities provide data about their area, including existing species, soil chemistry, wildlife habitat, and the overall health of the landscape.
The Pennsylvania Natural Heritage Program website lists four ecological subgroups of seepage wetlands by plant: Golden Saxifrage–Pennsylvania Bitter-Cress Spring Run; Golden Saxifrage– Sedge Rich Seep; Serpentine Seep; and Skunk-cabbage–Golden Saxifrage Seep.
The Golden Saxifrage–Sedge Rich Seep exists in north western and north eastern Pennsylvania. This type covers a small area, usually less than 1.24 acres.
The Serpentine Seep exists in the Piedmont section of the southeastern part of the state. It only develops where serpentine bedrock is exposed or near the surface, resulting in a limited number and range. It belongs to the serpentine barrens complex, which contains rare plants specifically adapted to this environment. Minerals, such as calcium, chromium, iron, magnesium, and nickel, in the groundwater affect the flora. Overall, this seep is usually dominated by grasses and rushes, such as tufted hairgrass (Deschampsia cespitosa), rice cutgrass (Leersia oryzoides), spike-rush (Eleocharis tenuis var. pseudoptera), and deer-tongue grass (Dichanthelium clandestinum). This ecosystem is critically endangered due to its rarity, as well as development, and other factors causing habitat destruction.
The Golden Saxifrage–Pennsylvania Bitter-Cress Spring Run and the Skunk-Cabbage–Golden Saxifrage Seep exist throughout the entire state. The Golden Saxifrage–Pennsylvania Bitter-Cress Spring Run exists immediately adjacent to springs. The dominant plant species are Golden saxifrage (Chrysosplenium americanum), Pennsylvania bittercress (Cardamine pensylvanica), and watercress (Nasturtium officinale).
The Skunk-Cabbage–Golden Saxifrage Seep contains thin to moderately dense growth of broadleaf and grass-like plants surrounded by shrubs and trees from the adjacent forest.
Herbaceous (grass-like) species dominate, but the flora is diverse, particularly when mineral levels are higher, altering the pH. Common plants include turtlehead (Chelone glabra), red maple (Acer rubrum), Jack-in-the-pulpit (Arisaema triphyllum), Pennsylvania bittercress (Cardamine pensylvanica), sedge (Carex prasina), winterberry (Ilex verticillata), spicebush (Lindera benzoin), hornbeam (Carpinus caroliniana), skunk-cabbage (Symplocarpus foetidus), golden saxifrage (Chrysosplenium americanum), cinnamon fern (Osmunda cinnamomea), sedge (Carex scabrata), and jewelweed (Impatiens capensis),
Finally, Pennsylvania has many seeps due to its numerous sedimentary rock (minerals and organic matter which are compacted) formations. Water soaks into the ground from the surface until it reaches impervious rock; then, it flows along this layer until it reaches a point where it can surface, forming a seep. Specifically, Adams County has multiple seeps; most of which are located in Franklin and Menallen Townships. Some are located in Caledonia State Park and Michaux State Forest.
For additional information about palustrine plant ecosystems in Pennsylvania, please examine Terrestrial and Palustrine Plant Communities in Pennsylvania by Jean Fike. For data about seeps in Adams County, please view A National Areas Inventory of Adams County, Pennsylvania by Pennsylvania Science Office of The Nature Conservancy and the Adams County Office of Planning and Development.
