Overview of study area and watersheds
The western Virginia study region includes the Valley and Ridge and the Blue Ridge physiographic provinces in the central Appalachian Mountains (Fig. 2). The region consists of parallel mountain ridges ranging from 750 to 1500 m above sea level. Forest cover is nearly complete and predominantly deciduous. The main bedrock types (classes) include igneous (mafic and felsic) rocks along the crest and eastern flank of the Blue Ridge province, with sedimentary (siliceous and argillaceous) rocks along the western flank of the Blue Ridge province and on the ridges of the Valley and Ridge Province (Dicken et al., 2005; Gathright, 1976; Sullivan et al., 2007). Most of the mountain stream watersheds in the region are small (2-20 km2) and the landscape is mostly protected or managed as public land, including SHEN and two U.S. Forest Service (USFS) National Forests (Fig. 2). A summary of the watershed size, dominant bedrock class, and land designation of the three distinct watershed sampling subsets (decadal, quarterly and weekly) are provided in Table 1.