Microbial Communities and Associated Enzyme Activities in Alpine Wetlands with Increasing Altitude on the Tibetan Plateau

Microbial communities, enzyme activities and soil physiochemical characteristics were investigated in alpine wetlands with altitude changes in the Nyainqentanglha Mountains on the Tibetan plateau. The results showed that with an increasing altitude gradient, soil physicochemical properties such as total organic carbon (TOC), total nitrogen (TN), water-soluble organic carbon (WSOC), water-soluble organic nitrogen (WSON) and pH decreased coincident with a decrease in mean annual temperature (MAT). Bacteria biomass, fungal biomass and actinobacterial biomass all decreased with an increase in altitude gradient. The ratio of Gram-positive bacteria to Gram-negative bacteria and the ratio of cyclopropyl to precursor fatty acids all indicate that the level of environmental harshness intensified with an increase in altitude. We also found that soil enzyme activities such as phenol oxidase, peroxidase, L-asparaginase, protease, urease and alkaline phosphatase all consistently decreased with an increase in altitude gradient. Additionally, the activities of peroxidase, protease and alkaline phosphatase declined, mainly due to a reduction in enzyme activities with temperature rather than the reduction of associated microbial biomass. Statistical analysis showed that both microbial biomass and enzyme activities were significantly influenced by mean annual temperature, suggesting that temperature is a key factor that affects microbial communities and soil enzyme activities in alpine wetlands on the Tibetan Plateau and indicating that climate warming may significantly impact these areas.