放牧对荒漠草原植物生物量及土壤养分的影响

Effects of grazing on plant biomass and soil nutrient in desert steppe

以宁夏荒漠草原为研究对象,探讨放牧对荒漠草原植物多样性、生物量及土壤养分特征的影响。结果表明,放牧对荒漠草原植物群落多样性、均匀度和丰富度影响显著。植物群落多样性和均匀度随着放牧强度的增加均呈先增加后降低的趋势,在轻度放牧达到最大值。同围封禁牧相比,重度、中度和轻度放牧草地的植物地上和地下部生物量显著降低,分别降低了43.8%、42.0%、15.4%和27.7%、16.2%、11.9%。土壤有机碳随着放牧强度的增加而降低,而土壤全氮含量随着放牧强度的增加呈先增加后降低的趋势。围封禁牧草地土壤有机碳比重度放牧增加了18.1%,而土壤全磷、速效磷和全钾含量分别降低了21.1%、51.9%和11.0%。土壤有机碳含量对植物群落地上和地下部生物量的影响大于土壤全氮、全磷、全钾、速效磷和速效钾。放牧干扰下荒漠草原土壤环境及其养分含量,能在一定程度上反映植物群落多样性和生物量的变化。

Effects of grazing on plant diversity, biomass and characteristics of soil nutrients were examined in a desert steppe in Ningxia. The result indicates that the grazing has significant effects on plant diversity, evenness and richness. With the increase of grazing intensity, the plant diversity and evenness are decreased after an initial increase and are the highest in the light grazing plots. As compared with the ungrazed plots, the grazed plots （heavy grazing, moderate grazing and light grazing） result in significant decreases of the aboveground and belowground biomass by 43.8%, 42.0%, 15.4% and 27.7%, 16.2%, 11.9%. With the increase of the grazing intensity, soil total nitrogen is decreased after an initial increase, and soil organic carbon is decreased. Compared with the grazed plots, soil organic carbon is increased by 18.1% in the ungrazed plots, while total phosphorus, available phosphorus and total potassium are decreased by 21.1%, 51.9% and 11.0%, respectively. The effects of soil organic carbon on aboveground biomass and belowground biomass are more significant than those of other soil properties （total nitrogen, total phosphorus, total potassium and available potassium）. The soil environment and nutrients are influenced by grazing disturbance to reflect plant diversity, community biomass change of desert steppe.