Document: DAV-3-6-2

Soil rhizosphere foodwebs in agroecosystems: Impacts of herbivory and tillage management.

COLEMAN, D.C.* and S.FU

University of Georgia, Athens, GA, U.S.A. 1

Abstract:
Soil rhizospheres are one of the principal "hotspots" of terrestrial ecosystems. Using isotopic Carbon tracer techniques, we measured impacts of aboveground herbivory on rhizosphere microbial growth and subsequent repercussions in an agroecosystem detrital food web. With a simulation model of decomposition of 14C-labelled litter, we measured relative contributions of bottom-up and top-down forces in the detrital foodweb. Microbial biomass was more resource-regulated, and microbivorous fauna was more sensitive to second- and third-order predators in the system. Implications for biodiversity and resource conservation are discussed.

Keywords: Rhizosphere, herbivory, carbon isotopes

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This abstract is being presented at: 11:00 AM in session:
Symposium # 21: The Rhizosphere: Top-Down and Bottom-Up Approaches.