Microbial Communities of Alpine Meadow Soil in the Eastern Qinghai-Tibetan Plateau Subjected to Experimental Warming and Grazing*

Abstract

oil microbes are important for many underground ecological processes and the change in their total biomass and community structure is regarded as a sensitive indicator for climate warming and human disturbances.Through open top chambers(OTCs) warming and clipping plus dung application,the effects of warming and grazing on soil microbial biomass and community structure were determined in an alpine meadow on the eastern Qinghai-Tibetan Plateau.The profiles of microbial phospholipid fatty acids(PLFAs) showed that soil microbial communities were dominated by bacteria in the growing seasons.An increase of 1.17 ℃ by OTCs warming soil at 10 cm depth resulted in a rise of 34.58% of total PLFAs,while the clipping plus dung application in spring caused a rise of 65.77%.Both experimental warming and grazing led to a significant change in soil microbial community structure.Compared to the control treatment,OTCs warming increased bacterial PLFAs by 8.80% and decresaed fungal PLFAs by 17.48%.The ratio of bacteria to fungi changed from 7.3 to 9.6.Grazing also markedly increased bacterial PLFAs by 8.40% and decreased fungal PLFAs by 14.04%.The ratio of bacteria to fungi increased to 9.2.The effects of OTCs warming and grazing on soil microbial biomass and community structure were found more notable than those of OTCs warming or grazing alone.Our results suggest that climatic warming and human disturbances might cause significant changes in soil microbial communities in a short period of time,which could have important effects on carbon budget and nutrient cycling in the alpine meadow ecosystem in the eastern Qinghai-Tibetan Plateau.