Responses of soil biota to elevated CO2 in a chaparral ecosystem

被引:25
作者
Allen, MF [1 ]
Klironomos, JN
Treseder, KK
Oechel, WC
机构
[1] Univ Calif Riverside, Ctr Conservat Biol, Riverside, CA 92521 USA
[2] Univ Calif Riverside, Dept Plant Pathol, Riverside, CA 92521 USA
[3] Univ Guelph, Dept Bot, Guelph, ON N1G 2W1, Canada
[4] San Diego State Univ, Ecosyst Res Grp, San Diego, CA 92182 USA
关键词
carbon sequestration; chaparral; decomposers; elevated CO2; mycorrhizae; soil energy channel; soil fauna;
D O I
10.1890/03-5425
中图分类号
Q14 [生态学(生物生态学)];
学科分类号
071012 ; 0713 ;
摘要
Atmospheric CO2 is rapidly increasing without an integrative understanding of the responses of soil organisms. We sampled soils in a chaparral ecosystem at 18 intervals over a 3-yr period in replicated field chambers ranging from 250 to 750 ppm CO2 at 100 ppm increments. We assessed three distinct soil energy channels: mycorrhizal fungi, saprotrophic fungi-mite/collembola, and bacteria-protozoa/nematode. C allocation below-ground increased with elevated CO2, Standing crops of fungi and bacteria rarely changed with CO2. Mass of bacteria-feeding nematodes increased during wet periods, but the effects on soil bacteria were not,detectable. However, grazing of fungi by mites increased with increasing CO2 up to 550 PPM CO2. Above this threshold, allocation of C to the fungal channel declined. Direct measures of mycorrhizal fungi (percentage infection, arbuscular mycorrhizal [AM] fungal hyphal length) showed no changes with CO2 enrichment, but indirect measures (macroaggregates with newly fixed Q increased suggesting increasing allocation of C through this channel. We postulate that the lack of change in standing crop in microbes to elevated CO2 is due to increasing turnover and to increasing N deficiency. Assessing C sequestration and other impacts of elevated CO2 on ecosystems requires a comprehensive, interactive, and dynamic evaluation of soil organismal responses.
引用
收藏
页码:1701 / 1711
页数:11
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