不同退化梯度下大尤尔都斯高寒草原植物种群生态位特征

Study on niche characteristics of the plant community in the alpine grassland of Big Youerdusi under a degeneration gradient

采用Levins生态位宽度指数(BL_i)和Pianka生态位重叠指数(Q_(ik)),测定不同退化梯度下巴音布鲁克大尤尔都斯高寒草原17种主要植物的生态位宽度及生态位重叠。结果表明,未退化阶段,优势种紫花针茅(Stipapurpurea)的生态位宽度较高,轻度退化与中度退化阶段其生态位宽度减小,重度退化阶段又上升,其它物种根据群落结构变化生态位宽度发生变化。在不同退化梯度下均出现生态位较窄的种群生态位重叠较大的现象,物种间生态位重叠的变化是由种间生态学特性差异与草地退化对种间关系影响共同造成的。研究显示,在巴音布鲁克大尤尔都斯高寒草原,过度放牧导致草地退化,物种生态位重叠总体相对较低。

The Levins niche breadth index（BLi）and Pianka niche overlap index（Q_（ik））were used to study the niche breadth and the niche overlap of 17 main kinds of plants within different degradation gradient in an alpine grassland of Big Youerdusi.Results showed that the niche breadth of dominant species Stipapurpurea was higher than others in the non-degraded stage,it was decline in the light degradation and moderate degradation stages,and then it increased in the heavy degradation stages.The change of niche breadth of other species changed based on the community structure.There was a phenomenon that plant species with narrow niche breadth had high niche overlap in different degeneration stages;the reason for this change of niche overlap was the interactive effects of different species＇ ecological characteristics and grassland degradation on interspecific relationships.In conclusion,overgrazing has led to grassland degradation,and the plant species niche overlap is relatively low,in the alpine grassland of Big Youerdusi.