Biodiversity

The ecological significance of Sideling Hill Creek is explained by examining the location and quality of this watershed. Situated in the middle region of the Appalachian Mountains of Pennsylvania and Maryland, this stream is a direct tributary to the Potomac River. These are the main factors that influence the species and habitats of the watershed, and the remote nature of the region has historically dictated landuse patterns that have maintained natural features rather than destroying them.

The Potomac River drainage flows east to the Chesapeake Bay and the northern Atlantic Ocean. The aquatic life of Sideling Hill Creek is characteristic of other Atlantic slope watersheds and, for example, some of the freshwater mussels and fishes are not found in most other Pennsylvania streams, including the northern spike mussel and the Potomac sculpin. The stream itself is comprised of a repetitive mixture of riffle, run and pool environments, streambed types that vary from places dominated by fine silt, to areas of cobble, or solid shelves of bedrock. The rare Tennessee pondweed is an aquatic plant found rooted in quiet silty edges or pools, while in Maryland the endangered harperella is rooted in wet gravel/cobble shoals that are frequently covered and swept clean by flooding. There is even a bright green freshwater sponge inhabiting areas with slow current. The aquatic and stream-edge species are maintained by good water quality that is missing in some other streams of the region.

Polish Mountain, Town Hill and Sideling Hill are the pronounced mountain ridges that create the margin of the watershed. As folds in the ancient Appalachian Mountains, they are composed of very old rock layers, such as those created in the Devonian geologic period. Shale bedrock is an important characteristic of the region, and, where steep south-facing slopes consist of exposed and crumbling shale outcrops a unique habitat is found known as the Appalachian shale barren. These are essentially the hot deserts of eastern U.S., where dry, rocky soils reach temperatures in excess of 120 degrees F. Certain plants and animals have evolved to survive in these conditions. Dozens of these species are considered to be endemic to this habitat and are rare or endangered in both states. Included are the yellow, aster-like cat’s-paw ragwort plant and the properigea noctuid moth.