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Microbial Community Composition and Function beneath Temperate Trees Exposed to Elevated Atmospheric Carbon Dioxide and Ozone
Rebecca L. Phillips, Donald R. Zak, William E. Holmes and David C. White
Vol. 131, No. 2 (Apr., 2002), pp. 236-244
Stable URL: http://www.jstor.org/stable/4223247
Page Count: 9
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We hypothesized that changes in plant growth resulting from atmospheric CO₂ and O₃ enrichment would alter the flow of C through soil food webs and that this effect would vary with tree species. To test this idea, we traced the course of C through the soil microbial community using soils from the free-air CO₂ and O₃ enrichment site in Rhinelander, Wisconsin. We added either 13C-labeled cellobiose or 13C-labeled N-acetylglucosamine to soils collected beneath ecologically distinct temperate trees exposed for 3 years to factorial CO₂ (ambient and 200 μl l-1 above ambient) and O₃ (ambient and 20 μl l-1 above ambient) treatments. For both labeled substrates, recovery of 13C in microbial respiration increased beneath plants grown under elevated CO₂ by 29% compared to ambient; elevated O₃ eliminated this effect. Production of 13C-CO₂ from soils beneath aspen (Populus tremuloides Michx.) and aspen-birch (Betula papyrifera Marsh.) was greater than that beneath aspenmaple (Acer saccharum Marsh.). Phospholipid fatty acid analyses (13C-PLFAs) indicated that the microbial community beneath plants exposed to elevated CO₂ metabolized more 13C-cellobiose, compared to the microbial community beneath plants exposed to the ambient condition. Recovery of 13C in PLFAs was an order of magnitude greater for N-acetylglucosamine-amended soil compared to cellobiose-amended soil, indicating that substrate type influenced microbial metabolism and soil C cycling. We found that elevated CO₂ increased fungal activity and microbial metabolism of cellobiose, and that microbial processes under early-successional aspen and birch species were more strongly affected by CO₂ and O₃ enrichment than those under late-successional maple.
Oecologia © 2002 Springer