天山南麓山前平原植物群落物种多样性及空间分异研究

荒漠灌丛是天山南麓山前平原主要植被类型.本研究定量分析了山前平原植物群落物种多样性及生境尺度异质性的影响.结果表明:(1)天山南麓山前平原的植物群落多样性指数Simpson、均匀度指数McIntosh及丰富度指数Margalef都较低,在地貌带的过渡上,植物分布呈现均匀化.(2)海拔和地下水埋深是影响天山南麓山前平原植物群落物种多样性的重要环境指标.海拔梯度与物种多样性指数Simpson、Margalef及McIntosh均呈显著的线性正相关关系,物种多样性均随海拔高度的增加而增加;地下水埋深与物种多样性指数呈极显著的线性负相关关系,物种多样性随地下水埋深的增加而减小.(3)土壤含盐量与物种多样性指标无显著关系,但土壤含盐量与地下水埋深相关性显著,这是天山南麓山前平原土壤盐分空间异质性的一个重要特点.土壤盐分含量变化影响着植物群落物种组成,随土壤盐分含量增加,群落中盐生植物种类逐渐占据优势.(4)海拔的变化是决定天山南麓山前平原灌丛群落生境差异的主导因子.海拔差异表征了山前平原地貌、水文地质条件及土壤的变化,而随海拔变化的水热、水盐等干扰体系的差异则进一步导致了异质性的生境,进而影响不同植被类型中群落组成结构和多样性的差异.

Species Diversity and Spatial Heterogeneity of Plant Communities in Piedmont Plain of South Slope of Tianshan Mountains

Shrub is a dominant vegetation type in south slope of Tianshan Mountains,Luntai County.Meanwhile,it is also a relatively stable ecosystem type and plays vital ro1e for water and soil conservation in this region.The results were as follows:(1) The plant species diversity indices,such as Simpson index,McIntosh index and Margalef index,were low in south slope of Tianshan Mountains.With the transition of geomorphological belts,most of the distribution patterns of populations were spatially homogeneous.(2) Altitude and groundwater level had significant effect on plant species diversity in piedmont plain.The species diversity increased with the altitude increase and with groundwater level decrease.(3) Soil salinity had no significant effect on species diversity.The soil salinity significantly associated with the groundwater level.This is an important characteristic of the soil salinity spatial heterogeneity in piedmont plain.Soil salinity changes affected plant species composition.With soil salinity increased,the plant community dominated by halophytes gradually.(4) The altitude change is leading factor of habitat heterogeneity in piedmont plain.The altitude difference represents the change of geomorphology,hydrogeological status and soil conditions.The different of disturbance along altitude create environmental heterogeneity,moreover,which impact on structural characteristics of community and species diversity.