Abstract: In order to reveal the relationships between soil water and salt availability and diversity of Gymnocarpos przewalskii communities in which the species was dominating,the diversity characteristics,soil moisture and salinity of four different habitat types of G. przewalskii dominating vegetation communities were investigated in the western end of Qilian Mountains,and their relationships analyzed. The results showed that there were 22 species,belonging to 20 genera and 10 families,mainly Compositae,Chenopodiaceae and Gramineae. Plant species Pielou index and Margalef index of fore-land alluvial fan were the highest (0.90 and 1.55). In the range of 0～100 cm,the highest water content of fore-land alluvial fan was 5.73%,followed by dry bed,2.04%;the gravel stony desert and fore-land dry bed were the lowest,1.44% and 1.33% respectively. The soil of G. przewalskii habitats was mainly composed of sulfate and chloride,the major ions were Na⁺,Ca²⁺,SO^2-₄and Cl^-,and the total salt content of gravel stony desert soil was the highest (6.21 g·kg^-1),the fore-land alluvial fan was 1.64 g·kg^-1,the dry bed and fore-land dry bed were the lowest,0.84 g·kg^-1 and 0.36 g·kg^-1. As the soil depth increased,the total salt content in different habitats fluctuated to different degree. The concentration of HCO^-₃ negatively,however the soil moisture,Ca²⁺,Mg²⁺,CO^2-₃ concentration positively affected plant community diversity (P＜0.05). In conclusion,our study revealed that plant communities in G. przewalskii habitats were overall simple with a few species,and the diversity characteristics did not significantly differ among the investigated habitats. Soil water content,the concentration of HCO^-₃,Ca²⁺,Mg²⁺,CO^2-₃ ions were the main factors that affected plant species diversity in the communities.

Key words: G. przewalskii community, Species diversity, Soil moisture and salinity, Correlation analysis

摘要： 为探究孑遗植物裸果木群落物种多样性与土壤水分、盐分的关系，本研究以祁连山西端4种典型生境(干河床、砾石质荒漠、山前干河床和山前冲积扇)的裸果木群落为研究对象，分析了裸果木群落物种多样性、组成及其与土壤水、盐的相互关系。结果表明：祁连山西端裸果木群落植物共有10科20属22种，并以菊科、藜科为主。其中，山前冲积扇生境的裸果木群落物种Pielou均匀度指数、Margalef丰富度指数均高于其他生境(分别为0.90,1.55)。裸果木生境土壤含水率较低(1.89%)，且在不同生境中存在较大差异，并呈现出随土层深度增加而增加的变化趋势；生境土壤中阳离子以Na⁺和Ca²⁺为主，阴离子以SO^2-₄和Cl^-为主，其中砾石质荒漠生境的全盐量最高(6.21 g·kg^-1)，干河床生境最低(0.36 g·kg^-1)，各生境全盐量随土壤深度增加均出现不同程度的波动。相关分析结果显示，HCO^-₃显著负向影响植物群落多样性特征值，而含水率、Ca²⁺、Mg²⁺和CO^2-₃含量则显著正向影响该特征值(P＜0.05)。综上，裸果木群落中植物具有典型耐旱、耐盐的生态学特性，土壤含水率、HCO^-₃、Ca²⁺、Mg²⁺和CO^2-₃含量是影响裸果木群落物种多样性的主要因素。

关键词: 裸果木群落, 物种多样性, 土壤水分和盐分, 相关性分析