盐碱化梯度上草原植被空间异质性的数量分析

Quantitative analysis on the spatial heterogeneity of grass vegetation at different salinitly intensities

以物种出现的频率(p)作为植被空间分布的观测指标,采用幂函数法则(Power-law)对鄂尔多斯高原不同盐碱化草原上植物群落的空间异质性进行定量研究。结果表明:不同盐碱化梯度上,群落种类结构发生明显改变。轻度、中度、重度盐碱化梯度上出现频率最高的物种分别为羊草、寸草苔、碱蓬。植物群落以中生-旱中生植物为主要建群种;多年生草本植物占有优势;丛生型植物在不同盐碱化梯度上普遍分布,丛生型和分枝型植物分布广泛;种子传播方式为重力传播的物种占有较高比例。物种多样性随盐碱化程度加深而明显下降,均质性增高,不同盐碱区的群落的空间异质性表现出明显差异性,中度退化梯度上生态优势度最高。盐碱退化梯度上的群落变化与种群的繁殖策略、生活史对策、群落的再生产策略等生理与生态特性密切相关。

In this research we studied the vegetation heterogeneity variation in process of salinization in Ordos grassland.Regarding the frequency of occurrence as the observation,the spatial heterogeneity of Grassland plant species were analyzed by power-law at different salinity gradients.The results showed that the species structure in the community changed.The most frequent specie is Leymus chinensis in the light salinity site,Carex duriuscula in the medium salinity site,and Suaeda glauce in the heavy salinity site.Mesophytes and xerophytes play an important roles in the community;perennial herbs are the dominant species;Bunch-type plants have a comparative advantage,clusters types and branch types of plants widely distribute at different salinity gradients;Species spreading the seed by gravity mean a high proportion.The community heterogeneity at light and heavy salinity gradients is higher than that at moderate salinity gradient.As salinity intensity increases,the community spatial heterogeneity（δc） decreases;Population distribution shows fragmentation characteristics.At different salinity gradients,the changes of community are closely related to the physiological and ecological characteristics,such as the population reproductive strategies,life history strategies,strategies of community reproduction and so on.