Effects of a forest disturbance on shredder production in southern Appalachian headwater streams

Abstract

SUMMARY The effects of a forest disturbance were investigated by comparing production of leaf‐shredding aquatic insects in three streams draining a mature hardwood forest and three streams draining an 11‐year‐old, cable‐logged clearcut. Reference streams contained significantly greater mean annual standing crop of leaf material and significantly more slow‐processing leaf material than disturbed streams. Disturbed streams had a significantly higher mean annual standing crop of fast‐processing leaf material than the reference streams. Leaf‐shredding cranefly (Tipula abdominalis), caddisfly (Pycnopsyche gentilis), and stonefly (Tallaperla maria) larvae comprised over 95% of shredder biomass in all streams. Total shredder production was significantly greater (P<0.05) in disturbed versus reference streams, but individual production rates were not significantly different between stream types. Pycnopsyche gentilis larvae were present at higher densities and achieved significantly greater annual biomass in disturbed versus references streams, Biomass of P. gentilis was significantly correlated with the standing crop of fast‐processing, early successional leaf material in samples, whereas biomass of other shredders was correlated significantly with medium or slow‐processing leaf species characteristic of later stages of forest succession.