THE LEGACY OF HISTORIC LOGGING ON HEADWATER STREAMS IN PENNSYLVANIA

摘要

The countless streams that drain the tangled headwaters regions of Pennsylvania watersheds are distinctly rugged and remote. Their channels are relatively wide and shallow, with beds and banks comprised of loose sand, gravel, and cobbles (Figure 1). Fallen trees create natural logjams that trap sediment upstream and create scour pools. Its no wonder that Pennsylvania headwater streams contain more brook trout than any other state in the conterminous US. In the steepest parts of the headwater streams,bedrock outcrops constrict the riparian corridor and create beautiful waterfalls and bedrock knickpoints. The fingerprint of Pleistocene is also evident in many of these watersheds, where barren rock fields ("felsenmeir") or pockets of glacial till mantle the hill slopes and coarse, glacio-fluvial outwash gravels fill the valleys (Figure 1).