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Grazing can modulate the feedback between vegetation and soil nutrient dynamics (carbon and nitrogen), altering the cycles of these elements in grassland ecosystems. For clarifying the impact of grazing on the C and N in plants and soils in the desert grassland of Ningxia, China, we examined the plant biomass, SOC (soil organic carbon), total soil N and stable isotope signatures of plants and soils from both the grazed and ungrazed sites. Significantly lower aboveground biomass, root biomass, litter biomass and vegetation coverage were found in the grazed site compared to the ungrazed site, with decreases of 42.0%, 16.2%, 59.4% and 30.0%, respectively. The effects of grazing on plant carbon, nitrogen,  15 N and  13 C values were uniform among species. The levels of plant carbon and nitrogen in grasses were greater than those in the forbs (except for the carbon of Cynanchum komarovii and Euphorbia esula). Root 15 N and 13 C values increased with grazing, while the responses of root carbon and nitrogen to grazing showed no consistent patterns. Root 15 N and 13 C were increased by 79.0% and 22.4% in the grazed site compared to the ungrazed site, respectively. The values of SOC and total N were significantly lower in the grazed than in the ungrazed sites for all sampling depths (0-10 and 10-20 cm), and values of SOC and total N at the surface (0-10 cm) were lower than those in the deeper soils (10-20 cm). Soil  15 N values were not affected by grazing at any sampling depth, whereas soil  13 C values were significantly affected by grazing and increased by 19.3% and 8.6% in the soils at 0-10 and 10-20 cm, respectively. The soil  13 C values (-8.3‰ to-6.7‰) were higher than those for roots (-20.2‰ to-15.6‰) and plant tissues (-27.9‰ to-13.3‰). Our study suggests that grazing could greatly affect soil organic carbon and nitrogen in contrast to ungrazed grassland and that grazing appears to exert a negative effect on soil carbon and nitrogen in desert grassland.

In the forest of the Baohua Reserve in the Baohua Mountains, eastern China, six plant communities and 11 subcommunities were described using the Braun-Blanquet method. These communities can be assigned to four already described Chinese vegetation types. Curtis' Compositional Index (CI) and Shannon's diversity index were used to determine the successional stage and species diversity of the communities. The community of Brachystachyum densiflorum and Pinus massoniana and the subcommunity of Fraxinus chinensis and Quercus acutissima with Pueraria lobata had the lowest CI and would be an initial successional stage; the community of Phoebe sheareri and Cyclobalanopsis glauca had the highest CI and would be the final stage. The community of Brachystachyum densiflorum and Pinus massoniana and the subcommunity of Fraxinus chinensis and Quercus acutissima with Pueraria lobata, both pioneer successional stages, had the lowest species diversity. The climax communities had the highest diversity.

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