Soil Enzyme Activities in Different Degraded Alpine Grassland of Tibet

Soil enzyme activities in degraded alpine grassland were discussed in this paper.The results showed that:(1) compared with non-degraded grassland,the activities of soil celluase,urease and alkaline phosphatase in slight degraded grassland were all increased,and the similar trend was found in moderate degraded grassland except urease activity which was decreased;while the three kinds of soil enzyme activities were all decreased in serious degraded grassland.(2) In different kinds of soils,the sensitivity of the soil enzyme activities to soil environment change were generally in the order of alkaline phosphatase urease celluase;but all the soil enzyme activities ranked by the order of urease alkaline phosphatase celluase.(3) In different soils,we found significant positive correlation between soil enzyme activities and soil organic C(r=0.7288～0.9808,p≤0.01),and positive relationship between soil enzyme activities and soil total N,available N and available K,but negative correlation or significant negative correlation was found between soil enzyme activities and soil available P.The influence of soil pH on urease activity was obvious,but the influence on soil alkaline phosphatase and celluase activities was not obvious.(4) Under alpine and drought conditions in the Tibet Plateau,improved soil permeability,induced by moderate desertification in moderate or slight degraded grassland,played an important role in improving soil enzyme activities and further,accelerating the decomposition of soil organic matter as well as the forming of soil organic matter.(5) Soil enzyme activities could not only reflect the difference of soil fertility in different alpine degraded