Partitioning of foliar, root and microbial contributions to ecosystem respiration under elevated CO{sub 2} using {sup 13}C techniques
- National Center for Atmospheric Research, Boulder, CO (United States)
Increasing atmospheric CO{sub 2} stimulates photosynthetic rates but ecosystem implications of this stimulation are unclear. As part of an integerated experimental and modeling study of the response of two California annual grasslands to elevated CO{sub 2}, we used {sup 13}C to distinguish the CO{sub 2}, derived from soil organic matter decomposition, heterotrophic decomposition of current and the previous years` plant production, root, foliar and ecosystem respiration. A pulse of enriched {sup 13}CO{sub 2} was used to label plant material in 1993. In 1994, we measured {sup 13}CO{sub 2} and CO{sub 2} flux of soil respiration (including root respiration), ecosystem respiration (soil respiration + plant dark respiration), and heterotrophic respiration. Calculation of the difference in {sup 13}C content of these fluxes combined with a mixing model allowed us to partition the fluxes into the individual components. Decomposition of soil organic carbon contributed less than 10% of total ecosystem respiration. Heterotrophic respiration rates were similar in elevated and ambient CO{sub 2} treatments. Ecosystem respiration rates were more than 3 times greater in elevated than ambient CO{sub 2} treatment while soil respiration rates were closer to 2 times greater. Root respiration, calculated by 2 different methods, was as much as 5 times higher in elevated than ambient CO{sub 2} treatments. The demonstrated increases in respiration rates in these two nutrient limited annual grasslands suggest that increased carbon fixation can be quickly lost via respiration rather than being translated into increased plant production or ecosystem carbon storage.
- OSTI ID:
- 95806
- Report Number(s):
- CONF-9507129-; ISSN 0012-9623; TRN: 95:004728-0071
- Journal Information:
- Bulletin of the Ecological Society of America, Vol. 76, Issue 2; Conference: 80. anniversary of the transdisciplinary nature of ecology, Snowbird, UT (United States), 30 Jul - 3 Aug 1995; Other Information: PBD: Jun 1995
- Country of Publication:
- United States
- Language:
- English
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