SEDIMENTATION CYCLES IN A RIVER-MOUTH TIDAL FRESH-WATER MARSH

Tidal freshwater marshes are critical buffers that exist at the interf ace between watersheds and estuaries. Little is known about the physic al dynamics of tidal freshwater marsh evolution. Over a 21-mo period, July 1995 to March 1997, measurements were made of biweekly sediment d eposition at 23 locations in a 3.8-ha tidal freshwater marsh in the Bu sh River subestuary of the upper Chesapeake Bay. Biweekly accumulation showed high spatial and temporal variability, ranging from -0.28 g cm (-2) to 1.15 g cm(-2). Spatial variability is accounted for by habitat differences including plant associations, elevation, and hydrology. T emporal variability is accounted for by interannual climate variabilit y, the growth cycles of marsh plants, stream marsh interactions, fores t-marsh interactions, and animal activity.