Tuesday, June 5, 2007 - 11:45 AM
161

How does diversity of decomposing leaf litter affect temporal changes in litter chemistry and associated macroinvertebrate assemblages in a detritus-based stream?

John Stephen Kominoski and Catherine Mann Pringle. Institute of Ecology, University of Georgia, Athens, GA 30602

Initial chemistry of single-species leaf litter is often used to predict mixed-species breakdown dynamics. Here, we examine changes in litter chemistry at four species richness levels and stream macroinvertebrate assemblages colonizing decomposing litter. Using a full-factorial design of four dominant riparian tree species (Acer rubrum, Liriodendron tulipifera, Quercus prinus, and Rhododendron maximum), we examined changes in litter chemistry and macroinvertebrate assemblages in single- and mixed-species (n = 2 – 4) packs during 190 days in a southern Appalachian stream. Litter chemistry was initially different among packs, but became homogeneous through time. Our previous work found that litter species identity affected microbial biomass, but neither litter species diversity or identity affected macroinvertebrate biomass. In this study, macroinvertebrate assemblages were different among packs containing different litter species richness but not among chemically distinct, single-species packs. Functional feeding groups responded differently to litter species richness through time: shredders were most abundant in two-species packs at the beginning, whereas predators were most abundant in three- and four-species packs towards the end of the study. Our results suggest that litter species diversity has non-additive effects on stream macroinvertebrate assemblages and that these effects are not explained by temporal changes in litter chemistry during breakdown.


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