Seston Dynamics in Southern Appalachian Streams: Effects of Clear-cutting

Abstract

Suspended particulate matter (seston) was studied from July 1977 to July 1978 in two second-order streams in the southern Appalachian Mountains. In the first stream, which drains an undisturbed hardwood forest watershed, seston concentrations fluctuated with season (lowest during winter high flows) and with storm flows. Most organic and inorganic particles were smaller than 105 μm diameter. The second stream drains a watershed (formerly a hardwood forest) that was clear-cut in early 1977. Increased levels of both organic and inorganic seston were found in the latter stream, especially beginning 1 yr after clear-cutting (2 yr after construction of logging roads). Particles larger than 234 μm in diameter accounted for most of the increases in inorganic seston. These increases were probably due to sediments deposited in the stream bed during road building and transported downstream during periods of peak flow. Increased levels of organic seston were probably related to breakdown of debris that entered the stream during logging and reduced retention by leaf packs. We hypothesize that eventual recovery of the stream will be limited by the rate of recovery of the surrounding terrestrial ecosystem.Key words: seston, sediment, detritus, stream, clear-cut, roads