A STUDY OF LAKE BOTTOM SUCCESSION, COLONIZATION AND ECOSYSTEM CHANGE AT MOUNTAIN LAKE, GILES COUNTY, VIRGINIA

Mountain Lake, in Giles County Virginia, is an oligotrophic, high altitude, sub-alpine lake, and the only natural lake in the southern Appalachian Highlands. Since the beginning of 1998, Mountain Lake has been decreasing in size. At full the lake covers approximately 47 acres; by late 2002 it covered less than 25. The falling lake level is a result of extended drought conditions, as well as an apparent natural depth fluctuation discussed by Cawley et. al (2001). This paper focuses on plant colonization and field succession of the former lake bottom into a temporary meadow. The first five years of increasing exposure have produced five discernable bands or zones representing progressive soil drying, colonization by pioneering plants, increases in sedges and reeds, grasses and rushes, open meadow development, and encroaching woodland edge. Approximately 75 plant species are noted across the five zones. The surrounding forest composition and several additional ongoing changes in the local ecosystem are discussed.