Search National Agricultural Library (NAL) Digital Collections
Showing item
0 of from your search.
start over
Carbon storage in coarse and fine fractions of Pacific Northwest old-growth forest soils
- Abstract::
- Many assessments of soil C have been restricted to the <2-mm fraction, but C has recently been identified in >2-mm fractions of forest mineral soils. Our objective was to determine the importance of the >2-mm fraction to whole-soil C pools in Pacific Northwest old-growth coniferous forests. Seventy-nine pedons in 18 western Washington and Oregon forests were sampled to a depth of 100 cm. The <2-mm fraction was separated from the >2-mm fraction by air-drying, physically crushing soil, and sieving; C was determined by Leco combustion. The >2-mm fraction contained up to 46% of the whole-soil C and averaged 23% for the seven forests that had C in that fraction. Following treatment with sodium hexametaphosphate to disaggregate soil material, up to 20% of whole-soil C remained in the >2-mm fraction. Thus, the >2-mm fraction C appears to be in stable and unstable aggregates, as well as concretions. The whole-soil C in the surface 100 cm of mineral soil ranged from 30 to 400 Mg C ha(-1). Multiple regression analysis indicated this C pool was positively related to available water capacity, annual precipitation, and coarse woody debris (r2 = 0.63 to 0.66, n = 18 forests). Similar results were obtained with only the <2-mm soil C, which is the basis of previous regional evaluations. This suggests consideration of the >2-mm fraction does not alter our understanding of the importance of climate and soil texture as controls of soil C pools, but it does affect the quantification of soil C pools in many old-growth forests in the Pacific Northwest.
- Author(s):
- Homann, P.S. , Remillard, S.M. , Harmon, M.E. , Bormann, B.T.
- Subject(s):
- forest soils , old-growth forests , carbon sequestration , coarse-textured soils , fine-textured soils , soil texture , Oregon , Washington
- Description:
- Includes references
- Source:
- Soil Science Society of America journal 2004 Nov-Dec, v. 68, no. 6
- Language:
- English
- Year:
- 2004
- Collection:
- Journal Articles, USDA Authors, Peer-Reviewed
- File:
- Download [PDF]
- Rights:
- Works produced by employees of the U.S. Government as part of their official duties are not copyrighted within the U.S. The content of this document is not copyrighted.
