Community And Soil Characteristics Of Degraded Kobresia Meadow In The Upper Area Of Daitong River

Based on the investigation of plant communities, a study on the communitiesstructure, plant composition, productivity, diversity and soil physics and chemistryproperties of non-degradation, light-degradation, moderate-degradation,heavy-degradation and over-degradation Kobresia meadow were made in the upperarea of Daitong River. The influencing factors of restore the degraded alpinegrassland were discussed as well. The results show that:The structure and composition of alpine meadow plant communities changedsignificantly, with increasing degrees of degradation. The communities dominantspecies that grass families and sedges were utilized constantly which dominancedecreased, at same time, the dominance of edible weeds that livestock dislike eatingwere increasing then a gradual transition of dominant species form good forages tosome weeds and poisonous grass, compositae plants become the dominant species indegraded grassland eventually.The process of alpine meadow vegetation degraded, overgrazing resulted incoverage of good forages reduced drastically and some edible weeds coveragechanged so that the total coverage of community reduced significantly. Grasslandvegetation reduced make total biomass of community decreased, reducing the goodforage biomass played s decisive role in the total biomass changing. The totalaboveground biomass far less than the total underground biomass, with soil depthincreases underground, plants roots become less and less, and aggregated to thesurface of ground.Grazing is an important reason for the diversity changes of degraded alpinemeadow vegetation communities. Because grazing made the competitive of eachspecies and environment conditions changing, leading to the distribution of specieschanged in the community. With the increasing of degradation, richness index anddiversity index were higher in moderate-degradation, which in over-degradation werelowest. Soil physics and chemistry properties changed when alpine degraded. In the samedepth, soil moisture, the contents of organic matter, total phosphorus, availablephosphorus decreased with increasing of degradation. But the changes of soil bulkdensity and soil pH were opposite. Total nitrogen and available nitrogen contents inmoderate-degradation and over-degradation had the max and min. With increasingsoil depth, soil bulk density and soil pH increased, the changes of soil moisture,organic matter, total phosphorus, available phosphorus, total nitrogen, availablenitrogen were opposite.