摘要：We collected soil samples in alpine forest along an elevational gradient in the Shegyla Mountains on the Tibetan plateau to study the linkages between soil microbial communities, soil enzyme activities, and elevation. M icrobial communities, enzyme activities and soil physiochemical characteristics were investigated in alpine forest along an elevational gradient in the Shegyla Mountains on the Tibetan plateau. The results showed that with increasing altitude the biomass of bacteria, fungi, actinomycetes, grampositive bacteria and gram-negative bacteria all showed the mid-domain effect, which is a typical model for plants and animals along an elevational gradient. The ratio of gram-positive bacteria to gram-negative bacteria and the ratio of cyclopropyl to precursor fatty acids both indicate that the level of environmental stress did not significantly change with increased altitude. We found that the activities of soil enzymes, such as protease, urease and acid phosphatase, also showed the mid-domain effect. Additionally, we found that pH was significantly correlated with microbial community structure and enzyme activities along the elevational gradient, suggesting that pH is a key factor that affects microbial communities and soil enzyme activities in alpine forest on the Tibetan Plateau. Because pH is already widely recognized as a primary driver for horizontal distribution in soil bacteria, together these results suggest that, in both horizontal and elevational contexts, pH could be a universal factor determining soil bacterial spatial distribution.
