Forest stand age and fate of 13C-labeled Litter and Roots in soil organic matter fractions. (6237)
Authors:
J. Washburn* - Dept. of Crop and Soil Sci., Oregon State Univ.
R.P. Dick - School of Natural Resources, Ohio State Univ.
Abstract:
Understanding the belowground carbon (C) composition, distribution, and sequestration in forest soils is critical to understanding the global C cycle for climate modeling applications. The objective of this study is to compare the influence of forest stand age on soil C content and rate of C sequestration among 5 different soil organic matter fractions ranging in turnover times from 101 to 103 years. In the fall of 2002, at the Wind River Experimental Station in the Gifford-Pinchot National Forest located in southwest Washington state, replicated microcosms containing 13C-labeled Douglas Fir litter and roots were placed in 3 forest stand ages: 1) old growth (greater than 500 yrs); 2) 1977 clear cut-replant; and 3) 1994 clear cut-replant. The microcosms are being periodically and destructively sampled over two years. Two particulate organic matter (POM) density fractions (free POM, occluded POM) were separated followed by the classical solubility fractionation of the remaining soil organic matter (fulvic acid, humic acid and humin). These 5 fractions were analyzed for total C and 13C. Total C was reduced by 60% between the ‘94 clear-cut and the old growth stands, and 13C was detected in the mineral soil beneath 13C litter and root amendments 2 months after microcosms were put in place. Results
concerning the fate of labeled plant materials within soil C fractions will be discussed.
Speaker Information: Jennifer Washburn, Dept. of Crop and Soil Sci., Oregon State Univ., 3017 ALS Soil Science Oregon State University, Corvallis, OR 97331; Phone: 541-737-5718; E-mail:
Session Information: Monday, November 1, 2004, 12:55 PM-3:25 PM Presentation Start: 2:45 PM
Keywords: C sequestration; forests; C factionation and pools; stand age