HR: 11:05h
AN: B12B-04 INVITED    [Abstracts]
TI: Interactive effects of litter quality and soil mineralogy on temperate forest soil carbon response to temperature
AU: * Rasmussen, C
EM: crasmuss@ag.arizona.edu
AF: Soil, Water and Environmental Science Department, University of Arizona 1177 E. Fourth St. Shantz Bldg. #38, Tucson, AZ 85721, United States
AU: Horwath, W
EM: wrhorwath@ucdavis.edu
AF: Land, Air and Water Resources, University of California, Davis One Shields Ave PES Bldg., Davis, CA 95616, United States
AU: Southard, R
EM: rjsouthard@ucdavis.edu
AF: Land, Air and Water Resources, University of California, Davis One Shields Ave PES Bldg., Davis, CA 95616, United States
AB: Temperate forest soil organic carbon (C) represents a significant pool of terrestrial C that may be released to the atmosphere as CO2 with predicted climate change. To address feedbacks between climate change and terrestrial C turnover, we quantified forest soil C response to litter quality and temperature change as a function of soil parent material. We collected soils from three conifer forest-types dominated by ponderosa pine (PP), white fir (WF), and red fir (RF) from each of three parent materials, granite (GR), basalt (BS), and andesite (AN) in the Sierra Nevada of California. AN soils were dominated by short-range-order (SRO) minerals, GR soils by crystalline minerals, and BS soils by a mix of crystalline and SRO minerals. Field soils were incubated in the laboratory at their mean annual soil temperature (MAST), with addition of native 13C-labeled litter. Further, we incubated WF and RF soils at PP MAST with 13C-labeled PP litter; and RF soils at WF MAST with 13C-labeled WF litter to simulate a migration of MAST and vegetation type up-elevation in response to predicted climate warming. Results indicated that total CO2 and percent of CO2 derived from soil C varied significantly across forest-types, following the pattern of GR>BS>AN. Regression analyses indicated significant control of C mineralization and soil C priming by litter quality and SRO minerals. Addition of litter derived water-soluble compounds enabled priming of recalcitrant soil C in soils with high SRO mineral content, whereas water-soluble litter components did little to promote priming of extant soil C in soils of low SRO mineral content. Results further indicated a 10-300% increase in WF and RF forest-type soil C mineralization under climate change conditions that varied substantially between parent materials. Soils derived from andesite exhibited minimal change; whereas granite and basalt derived soils lost large amounts of soil C under climate change conditions. This study corroborates the varied response in soil C mineralization by parent material and highlights how the soil mineral assemblage may act to control conifer forest-type soil C response to climate change.
DE: 1865 Soils (0486)
DE: 4806 Carbon cycling (0428)
SC: Biogeosciences [B]
MN: 2007 Fall Meeting