THE INFLUENCE OF LEPIDOSTOMA (TRICHOPTERA, LEPIDOSTOMATIDAE) ON RECOVERY OF LEAF-LITTER PROCESSING IN DISTURBED HEADWATER STREAMS

Two headwater streams draining catchments 53 and 54 (C53 and C54, resp ectively) at the Coweeta Hydrologic Laboratory in western North Caroli na were treated with insecticide in 1980 (C53) and 1986-1988 (C54). Du ring recovery periods in both streams, Lepidostoma spp. were abundant, early colonizers. Densities of Lepidostoma in litterbags and benthic samples collected from recovering streams were substantially higher th an in untreated streams (pretreatment and reference streams). During t reatment years, leaf-litter processing rates were severely reduced rel ative to pretreatment and reference streams. In contrast, litter proce ssing rates in C53 and C54 during recovery were faster than those in u ntreated streams (pretreatment and reference). Rhododendron is one of the most refractory leaves commonly found in Coweeta streams; however, percent increase of rhododendron processing rates from treatment peri ods to recovery was greater than that of more labile red maple. Labora tory feeding experiments were performed in order to examine and quanti fy use of rhododendron and red maple litter by Lepidostoma larvae. In the laboratory, Lepidostoma consumed significantly more rhododendron ( 1.062 mg AFDM/mg AFDM body wt/day) than red maple (0.479 mg AFDM/mg AF DM body wt/day) (P = 0.001). Results suggest that changes in the taxon omic composition of stream macroinvertebrate communities due to distur bance may have significant effects on ecosystem processes for at least 2 yr after termination of disturbance. Lepidostoma colonize rapidly f ollowing disturbance, enhancing the restoration of vital ecosystem pro cesses such as litter decomposition in Coweeta streams.