Separating root and soil microbial contributions to soil respiration: A review of methods and observations

Hanson, P J and Edwards, N T and Garten, C T and Andrews, J A (2004) Separating root and soil microbial contributions to soil respiration: A review of methods and observations. Biogeochemistry, 48 (1). pp. 115-146.

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Forest soil respiration is the sum of heterotrophic (microbes, soil fauna) and autotrophic (root) respiration. The contribution of each group needs to be understood to evaluate implications of environmental change on soil carbon cycling and sequestration. Three primary methods have been used to distinguish hetero- versus autotrophic soil respiration including: integration of components contributing to in situ forest soil CO2 efflux (i.e., litter, roots, soil), comparison of soils with and without root exclusion, and application of stable or radioactive isotope methods. Each approach has advantages and disadvantages, but isotope based methods provide quantitative answers with the least amount of disturbance to the soil and roots. Published data from all methods indicate that root/rhizosphere respiration can account for as little as 10 percent to greater than 90 percent of total in situ soil respiration depending on vegetation type and season of the year. Studies which have integrated percent root contribution to total soil respiration throughout an entire year or growing season show mean values of 45.8 and 60.4 percent for forest and nonforest vegetation, respectively. Such average annual values must be extrapolated with caution, however, because the root contribution to total soil respiration is commonly higher during the growing season and lower during the dormant periods of the year.

Item Type: Article
Additional Information: This research is sponsored by the Program for Ecosystem Research, Environmental Sciences Division, Office of Health and Environmental Research, U.S. Department of Energy under contract No. DE-ACO5-96OR22464 with Lockheed Martin Energy Research Corporation. We thank Jeff Amthor, Mac Post, and two anonymous reviewers for their helpful comments on earlier drafts of this manuscript. Publication No. 4843, Environmental Sciences Division, Oak Ridge National Laboratory.
Uncontrolled Keywords: rhizosphere - root respiration - soil CO2 efflux - soil respiration
Author Affiliation: Oak Ridge National Laboratory
Subjects: Soil Science and Microbiology
Divisions: General
Depositing User: Mr Siva Shankar
Date Deposited: 29 Feb 2012 09:33
Last Modified: 29 Feb 2012 09:33
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