HR: 08:15h
AN: B51E-02    [Abstracts]
TI: Implications of the Rhizosphere Effect on Soil Organic Matter Decomposition
AU: * Cheng, W
EM: wxcheng@ucsc.edu
AF: University of California, Environmental Studies, Santa Cruz, CA 95064 United States
AB: Roots of higher plants are a key functional component of belowground systems and one of the main soil-forming agents and they interact with virtually all soil components and processes. Plant roots and their associated rhizosphere processes are major gateways for nutrients and water cycles through all plant-soil systems and contribute as much as 50% of the total CO2 release from terrestrial ecosystems. The rhizosphere effect on soil organic matter decomposition is often referred as the change of soil organic matter decomposition rates solely caused by the presence of living roots as compared to bare soil. Both biotic and abiotic factors have been found to influence the level of rhizosphere effects on soil organic matter decomposition. Based on published studies, rhizosphere effects on the rate of soil organic matter decomposition range from 70 % suppression to 300 % stimulation. In this presentation I propose that the rhizosphere effect on soil organic matter decomposition represents an emergent property between roots and soil, and a key feedback mechanism between the plant component and the soil component in terrestrial ecosystems. This feedback mechanism operates in time scales from momentary to evolutionary. Because of the magnitude and the significance of the rhizosphere effect, many soil processes cannot and should not be understood in separation from root-associated processes, and vice versa, many important root-associated processes cannot be realistically studied under soil-less conditions. Therefore, the rhizosphere effect should be considered as one of the fundamental links between the aboveground component and the belowground component in terrestrial ecosystems.
DE: 0414 Biogeochemical cycles, processes, and modeling (0412, 0793, 1615, 4805, 4912)
DE: 0428 Carbon cycling (4806)
DE: 0470 Nutrients and nutrient cycling (4845, 4850)
DE: 0476 Plant ecology (1851)
DE: 0486 Soils/pedology (1865)
SC: Biogeosciences [B]
MN: Fall Meeting 2005