气温上升对草地土壤微生物群落结构的影响

在 2 0世纪内 ,全球气温已经上升了 0 .6℃ ,并预计到本世纪末仍将上升 1.4～ 5 .8℃。全球气候变暖对生态系统的潜在影响 ,生态系统对气温上升的反馈已成为国际生态学界的研究热点 ,而且所研究的系统也已经从过去简化的模拟系统到复杂的真实生态系统。但是 ,现有对真实生态系统的研究大部分集中在地上植物群落和土壤气体交换等领域 ,对在土壤有机碳分解和保护中起决定作用的土壤微生物研究较少。为此 ,在美国大平原地区进行人工提高气温 (上升 1.8℃ ) ,来研究土壤微生物对气温上升的反应。结果表明 :增温对土壤微生物的总生物量没有显著效应 ,但可以提高微生物的 C∶ N比。另外 ,磷脂肪酸分析发现 ,气温上升显著降低土壤微生物量中的细菌比重 ,提高真菌的份额 ,从而显著提高了群落中真菌与细菌的比值。而且 ,通过对土壤微生物底物利用方式和磷脂肪酸特征的主成份分析 ,发现增温导致了土壤微生物群落结构的转变。可见 ,气温上升可能是通过提高土壤微生物中真菌的优势 ,而导致群落结构的变化。该变化将可以提高微生物对土壤有机碳的利用效率 ,并利于土壤有机碳的保护

Impacts of experimental atmospheric warming on soil microbial community structure in a tallgrass prairie

Global surface temperature is predicted to increase by 1.4 to 5.8℃ by the end of this century. However, the impacts of this projected warming on soil carbon balance and budget of terrestri alecosystems are not clear. One major source of the uncertainty stems from warm ing effects on soil microbes, which exert dominant influence on soil organic car bon decomposition and storage in terrestrial ecosystems. We have therefore conducted an experiment in a tallgrass prairie ecosystem in the US Great Plains to study soil microbial responses to artificial warming of about 1.8℃. Our data showed that warming did not induce significant differences in soil microbial biomas ssize, but increased microbial biomass C∶Nratio. Also, warming caused an increase in bacterial contribution and a decrease in fungal contribution to the total microbial PLFAs, consequently inducing an increase in the ratio of fungi to bacteria within the whole soil microbial community. Moreover, principle component analysis of substrate utilization patterns and the profiles of phospholipid fatt yacids showed that warming caused a shift in soil microbial community structure . Together, our results indicate that this shift in microbial community structure induced by experimental warming may be attributed to the increase in soil fungal dominance and the decrease in bacterial dominance. The observed shift in soil microbial community structure may increase microbial carbon use efficiency and benefit organic carbon protection in the soil.