Abstract: The effect of grazing disturbance on plant diversity,soil physical and chemical properties,and soil nutrients characteristics of Stipa Baicalensis Roshev.grassland was studied.The results show that the number of species,plant diversity and vegetation coverage were significantly decreased along with the increasing of grazing intensity.The effects of grazing disturbance on soil physical and chemical properties were primarily manifested in increased soil bulk density,decreased soil water content.Under heavy grazing,soil bulk density increased to 1.36 g/cm³,soil water content decreased to 12.37%,vegetation coverage reduced,and the ground biomass was also significantly lower.Grazing disturbance led to the change of soil organic carbon pattern,soil organic carbon content in 0-10 cm decreased gradually with light grazing,but the organic carbon transferring to deep soil was accelerated,organic carbon levels in 10-20 cm and 20-30 cm were significantly higher than those in other plots,and soil organic carbon content of the profile increased 7.19% than non-grazing grassland.Total soil nitrogen content(0-10 cm,10-20 cm) increased under light grazing;under medium grazing,it was significantly higher than that in other plots.Soil total phosphorus content was not significantly different among plots,except that it was decreased significantly under heavy grazing.The increase of plant diversity,aboveground biomass,and underground biomass was a response to light grazing disturbance,while under heavy grazing,plant diversity and vegetation coverage reduced,soil physical and chemical properties changed,soil nutrient resource became scarce,and grassland appeared a trend of degradation.

Key words: Grazing disturbance, Plant diversity, Grassland productivity, Soil nutrient

摘要： 以贝加尔针茅(Stipa baicalensis Roshev.)草甸草原为研究对象,研究不同强度放牧干扰对贝加尔针茅草原群落植物多样性、土壤理化性状及养分特征的影响。结果表明:随着放牧强度的增加,群落物种数、植物多样性和植被盖度均显著降低;放牧干扰对土壤理化性状的影响主要表现在,随着放牧强度的增加,土壤容重升高,土壤含水量减小,重度放牧草地土壤容重增加到1.35g/cm³,含水量仅为12.37%;放牧导致土壤有机碳格局发生改变,轻度放牧下表层(0-10cm)土壤有机碳含量逐渐降低,但有机碳向深层土壤的转移量增加,深层土壤(10-20cm、20-30cm)有机碳含量均显著高于其它样地,且整个剖面土壤有机碳含量较对照样地提高了7.19%。土壤全氮含量(0-10cm、10-20cm)在轻度放时有所增加,中度放牧全氮含量显著高于其它样地,全磷含量除了在重度放牧时显著降低,在其它样地间均无显著差异。研究表明植物多样性、地上地下生物量的增加及土壤有机碳格局的改变是贝加尔针茅草原对轻度放牧干扰的一种响应,而重度放牧,草地植物多样性减少、植被盖度降低、土壤物理性状发生改变、养分资源趋于匮乏,草地出现退化的迹象。

关键词: 放牧干扰, 植物多样性, 草地生产力, 土壤养分