HR: 1340h
AN: B23D-1579    [Abstracts]
TI: Climate Effects on Soil Carbon Sequestration in a Grass, Oak and Conifer Ecosystem of California
AU: * Pittiglio, S L
EM: pittiglio@gmail.com
AF: University of California, Davis, 1 Shields Ave Plant and Environmental Sciences Building University of California, Davis, Davis, CA 95616,
AU: Zasoski, R
EM: rjzasoski@ucdavis.edu
AF: University of California, Davis, 1 Shields Ave Plant and Environmental Sciences Building University of California, Davis, Davis, CA 95616,
AB: Dissolved organic matter (DOM) leaching from decomposing detritus accumulated above mineral soils is an important carbon (C) and nitrogen (N) flux that influences biogeochemical processes, C sequestration and the health of individual ecosystems. Previous studies have shown that the main process controlling DOM mobility in soils is sorption in the mineral horizons that adds to stabilized organic matter pools. The objective of this study was to determine the effect of temperature and incubation time on DOC and DON biodegradation and sorption in the mineral soil. Surface litter from a grass, oak and a conifer site were leached with deionized water for 5, 15 or 96 hours at 4, 20 or 30oC. The resulting DOM solutions were characterized using 13C NMR, XAD-8 resin and UV-vis spectroscopy. The biodegradable fraction (BDOC) of these solutions was quantified using inoculum from A horizon soils. The DOM solutions were also used in sorption experiments on A horizon soils. Supernatant from the A horizon sorption experiment was then used in a sorption experiment on Bt horizon soils and analyzed for BDOC using Bt horizon inoculum. The ability of the soils to adsorb DOC increased with increasing aromaticity in the DOC solution. Therefore, conifer DOM exhibited greater sorption than oak and grass DOM due to higher aromaticity. In all horizons, we observed net release of indigenous OM when OM-free solution was added. Net release of OM was greatest from the soils from the pine site, which had the greatest OM content among the soils we studied. ***Results still pending***
DE: 0428 Carbon cycling (4806)
DE: 0469 Nitrogen cycling
DE: 0486 Soils/pedology (1865)
SC: Biogeosciences [B]
MN: 2007 Fall Meeting