LITTER BREAKDOWN AND INVERTEBRATE SHREDDERS IN A DETRITUS-LIMITED APPALACHIAN STREAM.

S.L. Eggert¹ and J.B. Wallace^1,2. ¹Institute of Ecology, University of Georgia, Athens, Georgia, USA 30602, ²Department of Entomology, University of Georgia, Athens, Georgia, USA 30602

Leaves and wood make up > 88 % of the energy inputs to Appalachian headwater streams. We measured breakdown rates of red maple and rhododendron leaves, and small wood for three years in a litter-excluded stream and reference stream in western North Carolina. We hypothesized that leaf breakdown rates would decline in the litter-excluded stream as shredder production decreased, and expected higher wood breakdown rates in the litter-depleted stream with increased microbial activity on wood. Rhododendron breakdown rates did not differ significantly between streams during any year. Red maple breakdown rates were similar between streams during year 1, but were significantly greater (p<0.05) in the reference stream during years 2 and 3. Wood breakdown rates were significantly greater (p<0.01) in the litter-excluded stream. In the reference stream, total shredder production was similar in litterbags and mixed substrates. Shredder production in litterbags in the litter-excluded stream was 4x greater for red maple leaves and 3x greater for rhododendron leaves than shredder production in mixed substrates of the litter-excluded stream. The litterbags served as resource islands for shredder invertebrates in the litter-depleted stream, and demonstrate the tight linkage between invertebrate shredders and leaf litter inputs.