Effects of fencing on microbial communities and soil enzyme activities in Damxung alpine grassland

The deterioration of soil ecosystem and soil degradation related to overgrazing were serious and cannot be restored in short period. In order to determine the impacts of fencing on the soil enzyme activities and soil microbial communities in Damxung steppe, the activities of β-glucosidase, invertase, phenol oxidase, peroxidase, L-asparaginase, protease, urease and alkaline phosphatase were investigated, as well as the biomass of bacteria, fungi, actinomycete, gram-positive bacteria and gram-negative bacteria. Water soluble organic carbon (WSOC) and water soluble organic nitrogen (WSON) in soils with all fencing treatments were significantly higher (P＜0.05) than that in grazing soils. There were significant variations of soil moisture and pH between grazing and fencing 6 years. Invertase and L-asparaginase activities significantly increased with the fencing year extended. The biomass of bacteria, actinomycete and gram-positive bacteria in soil with 6 years fencing were significantly higher (P＜0.05) than that in soil. All of these results suggested that fencing changed not only soil physicochemical properties, but also soil enzyme activities and microbial communities. The further pearson correlation analysis showed that WSOC, WSON and moisture had significantly positive correlation with soil enzyme activities and soil microbial communities which suggested that all of tested factors could be good indicators for grassland degradation and restoration. All of these results showed that fencing helped improving soil organic matter to promote growth of microorganism and recovery of alpine grassland ecosystem.