Responses Of Soil Biological Properties To Different Grazing Managements In Damxung Alpine Meadow

Soil protozoan is a significant componet of soil ecosystem, which could resppnse to soil environmental variation sensitively as a potential biological indicator of soil disturbance and soil quality. Alpine meadow is one of the highest widespread vegetation types in Tibetan Plateau. And it plays an important role on the east-Asian biological diversity, ecosystem balance and local socio-economy. Recently the grassland degradation in Tibetan Plateau, induced by overgrazing and climate change, has become a serious issue. For resolving this problem, we detected the soil physicochemical properties, soil microbial biomass, microbial activities, soil enzyme acitivties and soil protzoa under six different grazing intensities (artificial pasture experiment site (oat (AG-O), highland barley (AG-B)), the area out of the artificial pasture experiment site (OAG), the winter grazing site (WG-E, WG-W), the area out of the fenced winter grazing site (OWG), the fenced grazing site (GF-W), the area out of fenced garzing site (OGF), the heavy grazing site in native meadow(HG)) and revealed the relationships between soil microbe, soil enzyme, soil protozoa and grazing management practices. Then we would clarify the meachanisms of respose of soil properties to grazing and indicative significance in soil degradation. The possibility of soil protozoa used to reflect soil variation as an indicator would be determined to support theory foundation for consuturing monitor system of grassland degradation and grassland ecosystem’sustained development. The result are as followed:Grazing could significantly affect soil moisture and soil pH value in Damxung County. Soil microbial biomass were reduced significantly in HG site compared to others grazing treatment. Soil basal respiration showed a decrease with increasing grazing intensity. In2011, grazing significantly affected soil catalase, cellulase, protease, asparaginase and glutaminase, but soil urease activites in different grazing intensities didn’t show statistic difference. Soil enzyme activities displayed different variations in2012:soil catalase had the highest value at HG plot, and protease activity reduced with the increasing grazing intensity. However soil urease activities of soil samples in fence were significantly higher than that out of fence. Garzing signifaicntly affected soil protozoa in alpine meadow of Tibetan Plateau. Soil protozoa abundance in WG-W site significantly was much higher than the other sites, and the same trend also occurred in soil flagellate and ciliate abundance. However the number of individual amoeba was vast in GF-W and OWG sites with moderate grazing intensity.Soil fungi preying on protozoa couldn’t be isolated form soil samples from alpine meadow by the culturable method. We tried to isolate soil microbe in samples from Medog County, Tibet. And one incredulous fungi species was obtained, Mtzl-1.