Depth-related responses of soil microbial communities to experimental warming in an alpine meadow on the Qinghai- Tibet Plateau.

Although the effect of experimental warming on soil microorganisms has been well documented at surface horizons, less is known about its influence in subsurface horizons. An experiment was therefore carried out in an alpine meadow on the Qinghai- Tibet Plateau to examine the responses of microbial communities to experimental warming at five soil depths (0-10, 10-20, 20-30, 30-40 and 40-50 cm). Plots were passively warmed for 3 years in open-top chambers and compared with adjacent control plots at ambient temperature. Soil microbial communities were assessed by using phospholipid fatty acid ( PLFA) analysis. Our results showed clearly that 3 years of experimental warming increased microbial biomass consistently and significantly throughout the upper 50-cm soil profiles, as indicated by the changes in both microbial biomass carbon ( C) and total PLFA contents. The composition of microbial communities was also affected significantly by warming, but its effect depended on soil depth. While warming induced a community shift towards bacteria at the 0-10-cm depth, it tended to shift microbial communities towards fungi at the other, deeper, layers. These results indicate that warming had strong effects on soil microbial communities, including even those residing in subsurface horizons, which may help us to understand the microbial mediation of the feedback between terrestrial C cycling and climate warming. [ABSTRACT FROM AUTHOR]