Effects of 7 years experimental warming on soil bacterial and fungal community structure in the Northern Tibet alpine meadow at three elevations

A warming experiment was established along an altitudinal gradient (low elevation: 4313 m, mid-elevation: 4513 m and high elevation: 4693 m) in alpine meadows of the Northern Tibet to investigate the effects of warming on soil bacterial and fungal community structure. Elevation had significant effects on vegetation community coverage (CC), soil temperature (Ts) and pH, but not soil fungal diversity. Soil bacterial diversity at the high elevation was significantly lower than that at the low and mid-elevations, whereas there was no significant difference of soil bacterial diversity between the low and mid-elevations. After seven years of warming, soil fungal diversity was significantly increased at the mid-elevation but not the low and high elevations, and soil bacterial diversity was not significantly altered at the low, mid- and high elevations. Soil bacterial community structure was significantly altered at the low and mid-elevations but not the high elevation. Soil fungal community structure was significantly altered at all the three elevations. CC, Ts and pH significantly explained 20.55%, 5.30% and 12.61% of the variation of bacterial community structure, respectively. CC and Ts significantly explained 17.40% and 5.86% of the variation of fungal community structure, respectively. Therefore, responses of soil microbial community structure to warming may vary with elevation, which was mainly attributed to different vegetation coverage, soil temperature and/or pH conditions among the three elevations in this study alpine meadows.