整合分析增温和增CO2对土壤微生物的影响

摘要

土壤微生物在陆地生态系统碳氮循环中起着重要作用.气候变暖和CO2浓度增加是气候变化的两个重要方面.本研究整合分析了实验增温和CO2浓度增加对土壤微生物量和群落结构的影响.生态系统类型主要包括森林生态系统和草地生态系统.增温方法包括开顶式增温小室和热红外增温.增温时间有全天增温、白天增温和晚上增温.实验增温增加了土壤放线菌和腐生真菌,而CO2浓度增加减少了土壤革兰氏阳性细菌.实验增温对土壤革兰氏阴性细菌和总的磷脂脂肪酸量的影响随着年均温和年降水量的增加而减少.实验增温对土壤总的磷脂脂肪酸量、细菌含量、革兰氏阳性和阴性细菌的量的影响随着海拔的升高而增加.实验增温增加了草地生态系统的土壤总的磷脂脂肪酸量和放线菌含量,并增加了森林生态系统的土壤真菌和细菌的比值.开顶式增温小室增加了土壤革兰氏阴性细菌,而红外增温减少了土壤真菌和细菌的比值.白天增温增加了土壤革兰氏阴性细菌,而全天增温没有改变土壤革兰氏阴性细菌.因此,实验增温对土壤微生物的影响与生态系统类型、实验增温方法、增温时间、海拔和当地的气候条件有关.%Soil microbes play important roles in terrestrial ecosystem carbon and nitrogen cycling. Climatic warming and elevated CO2 are two aspects of climatic change. In this study, we used a meta-analysis approach to synthesise observations related to the effects of warming and elevated CO2 on soil microbial biomass and community structure. Ecosystem types were mainly grouped into forests and grasslands. Warming methods included open top chambers and infrared radiators. Experimental settings included all-day warming, daytime warming and nighttime warming. Warming increased soil actinomycetes and saprotrophic fungi, while elevated CO2 decreased soil gram-positive bacteria (G+). Mean annual temperature and mean annual precipitation were negatively correlated with warming effects on gram-negative bacteria (G–) and total phospholipid fatty acid (PLFA), respectively. Elevation was positively correlated with the warming effect on total PLFA, bacteria, G+ and G–. Grassland exhibited a positive response of total PLFA and actinomycetes to warming, while forest exhibited a positive response in the ratio of soil fungi to bacteria (F/B ratio) to warming. The open top chamber method increased G–, while the infrared radiator method decreased the F/B ratio. Daytime warming rather than all-day warming increased G–. Our findings indicated that the effects of warming on soil microbes differed with ecosystem types, warming methods, warming times, elevation and local climate conditions.