CHANGES IN PLANT DIVERSITY, BIOMASS AND SOIL C, IN ALPINE MEADOWS AT DIFFERENT DEGRADATION STAGES IN THE HEADWATER REGION OF THREE RIVERS, CHINA

Field surveys and experiment analyses were applied to detect the relationships between plant diversity, community biomass and soil resources at different degradation successional stages in the headwater region of three rivers in an alpine meadow. The chronosequence approach (space-for-time substitution) is a viable tool for obtaining integrated information within successional studies. The experimental plots were located in the Guoluo area, Which is part of the source region for the Yanglze and Yellow Rivers. The results showed not only that the quantities of roots and soil that are 'carriers' for cultivating soil roots were altered not only by disturbance (including overgrazing) and environmental factors but also that the proportion of the rhizome to soil at the 0-10 cm soil layer was enhanced by disturbance in heavy degradation. The plant community composition changed, and the number of plant species and the proportions of fine forage decreased. Moreover, soil fertility levels decreased remarkably, and the soil was degenerated. Plant community biomass levels at different degradation successional stages affected the soil microbial biomass carbon, soil organic carbon and also affected soil fertility conditions. Soil organic carbon and soil total nitrogen declined with grassland degeneration, and the distribution of soil organic carbon Was influenced greatly. The alpine species Kobresia pygmaea was at different degradation successional stages, and the Plant community biomass was significantly related to Soil nutrients. In the positive successional series, the composition of plant functional groups became complex gradually, plant species richness was gradually enhanced, and the change in the composition of each plant functional group also reflected the restoration degree plant community structure. Copyright (C) 2008 John Wiley & Sons, Ltd.