黑河中游荒漠绿洲过渡带植被多样性特征及其水分的影响

应用Simpson和Shannon-Wiener物种多样性指数、Margalef物种丰富度指数、Simpson物种优势度指数和Pielou物种均匀度指数对黑河中游荒漠绿洲过渡带的植被群落多样性及土壤含水量对植被多样性的影响进行分析。结果表明:1）黑河流域荒漠过渡带共有植物12科31属37种。灌木以红砂-珍珠猪毛菜为优势群落，草本以三芒草-苔草群落为优势群落，具有物种组成简单、多样性较低的特点。2）群落在植物生活型上以旱生、超旱生或盐生的小灌木和1年生草本植物占主导地位。3）灌木群落具有较高的丰富度指数和多样性指数，而草本群落具有较高的均匀度指数。各群落丰富度指数与多样性指数、均匀度指数之间存在极显著的相关性。4）除干沙层外，每个样地各土层的土壤含水量均随土层深度的加深土壤含水量依次增大，植被丰富度随土层持水量增大而增加，植被多样性和丰富度与各土层土壤含水量呈正相关。灌木根系主要分布在20～40 cm土层，草本根系主要分布在浅层0～20 cm。表明土壤水分对群落物种组成、 植被群落多样性具有重要的影响，在植被恢复建设中优先考虑土壤水分承载力。

Characteristics of Vegetation Diversity and Effects of Water in the Desert-oasis Region in the Middle Reaches of Heihe River Basin

The Simpson and Shannon-Wiener species diversity indices,Margalef species richness index,Simpson species dominance index and Pielou species evenness index were used to study the changes of the vegetation community diversity (VCD) occurring in the transition zone of desert oasis in the middle reaches of Heihe River,the effects of soil water on VCD.The results showed that.1) 37 species,31 genera and 12 families were found in the region.The dominant communities of shrub and herb were Reaumuria songarica-Salsola passerina,and Aristida adscensionis-Carex tristachya with the characteristics of simple species composition and low diversity.2) The communities were dominated by xerophyte,ultra xerophyte or halophyte shrubs and annual herbaceous plants.3) Shrub community had higher richness index and diversity index,while herb community had higher evenness index.The richness index,diversity index and evenness index of each community were significantly correlated.4) Except for the dry sand layer,the soil water content of each soil layer in each sample plot increased with soil depth; the vegetation richness increased with soil water holding capacity; the dominance and richness of vegetation were positively correlated with the soil water content of each soil layer.Shrub roots were mainly distributed in the 20-40 cm soil layer,while herbaceous roots were mainly distributed in the shallow soil layer (0-20 cm).The results showed that soil moisture had an important effect on community species composition and VCD,and soil moisture carrying capacity gave priority in vegetation restoration.