甘南高寒草甸退化对植物功能群物种多样性与物种多度分布的影响

Influences of alpine meadow degradation on species diversity and abundance distribution of plant functional groups in Gannan

【目的】探究甘南高寒草甸植物功能群多样性及其物种多度分布对退化的响应,分析随退化程度的加深不同植物功能群的群落构建机理及资源利用方式。【方法】研究以甘南高寒草甸为对象,采用样地调查法收集数据,使用物种多度模型对其进行拟合分析,并采用双向聚类分析对群落物种进行分类。【结果】随着退化程度的加深,植被优势种以禾本科和莎草科植物为主,逐渐变为杂类草功能群植物为主,杂类草功能群在群落多样性分布中起主导作用;全部物种多度分布随着退化程度的加深发生变化,其中,无退化草甸的最优拟合模型是VOLKOV,轻度退化草甸的最优拟合模型是GEO,中度退化草甸和重度退化草甸的最优拟合模型为BRO,资源分配模式由随机分配转向固定分配的分配模式;禾草功能群的最优拟合模型以生态位模型为主,资源分配方式由固定分配和随机分配共同主导,豆科功能群的最优拟合模型是BRO,资源分配方式以固定分配为主,杂类草功能群的最优拟合模型从中性模型向生态位模型转变,与全部物种多度分布的最优模型基本一致,且资源分配由随机分配向固定分配转变。【结论】杂类草功能群是影响群落物种多度分布的主要原因,但是禾草和豆科功能群的贡献也不可忽视。

[Objective]To investigate the response of species diversity and richness distribution of plant functional groups to degradation in the Gannan alpine meadow,we analyzed the community construction mechanism and resource utilization of different plant functional groups with the deepening of degradation.[Methods]We took the Gannan alpine meadow as the research object,collected the data by sample survey method,fitted the model of species multiplicity,and classified the community species by two-way cluster analysis.[Results]With the deepening of degradation,the vegetation species were dominated by gramineae and saxifragaceae,which were gradually changed to the domination of miscellaneous grasses.The functional group of the miscellaneous grasses played a dominant role in the distribution of the diversity of the community.The multidimensional distribution of all the species was changed with the deepening of degradation,in which the optimal fitting model for the non-degraded meadows was VOLKOV,for the mildly degraded meadows was GEO,and for the moderately and severely degraded meadows were BRO,where the resource allocation mode shifted from random to fixed allocation.The ecological niche model dominated the optimal fitting model for the grass functional group,and the resource allocation mode was dominated by both fixed and random allocation.The optimal fitting model for the legume functional group was BRO,and the resource allocation mode was dominated by fixed allocation.The optimal fitting model for the miscellaneous grass functional group shifted from neutral to neutral allocation mode.The optimal fitting model of the weed functional group shifted from neutral model to ecological niche model,consistent with the optimal model of the multidimensional distribution of all species.The resource allocation shifted from the random allocation to fixed allocation.[Conclusion]The weed functional group is the main reason influencing the multidimensional distribution of the community species.However,the contribution of the graminoid and legume functional groups should not be neglected.