中文摘要：

以野外样方调查数据为基础,采用重要值计算了多样性指数、均匀度指数、丰富度指数、优势度指数,对古尔班通古特沙漠南缘至腹地白梭梭群落林下植被的物种多样性进行了研究。结果表明：受降水梯度的影响,从南缘至腹地植被盖度变化范围在14%～36%,除南缘取样点（S1）受人类扰动较大,盖度有些波动外,总体呈现明显的下降趋势。但植株种群密度差异较小,初步推断,植被盖度的差异主要是由植株个体大小造成的,而不是植株种群密度。南缘至腹地,各样地的多样性指数、均匀度指数、丰富度指数均表现为先减后增的变化趋势,优势度指数变化趋势则与之相反。各指数的变化范围：物种数在5.9～11.4种/m2,多样性指数变化范围在1.0340～2.0971,各样地均匀度指数在0.6068～0.8760,优势度指数为0.2767～0.6643。距沙漠南缘6.57km处是物种多样性的一个重要转折点,是物种多样性较不丰富的地带。同时,对白梭梭群落林下植被在1m×1m,20m×20m,100m×100m三种尺度下,南缘到腹地植物物种数的变化分析得出,在100m2尺度以下,白梭梭群落林下植被的物种多样性随空间尺度的增大而增大。

英文摘要：

The species diversity is an important trait of plant ecological adaptive strategy.The Haloxylon persicum community is widely distributed in the Guerbantongtute Desert and plays an important role in stabilizing plant composite.However,the species diversity of the understory of Haloxylon persicum is poorly known.Our objectives are to investigate the species diversity of the understory of Haloxylon persicum from the southern edge to the desert hinterland of the Guerbantongtute Desert and to discuss the relationship between the variation of the understory of Haloxylon persicum natural population and in different distribution areas.A field investigation was conducted on distributed areas of Haloxylon persicum from the southern edge to the desert hinterland of the Guerbantongtute Desert from April to June in 2009,We investigated quantitative measures of species of the understory of Haloxylon persicum from the southern edge to the desert hinterland of the Gurbantunggut desert,including the population coverage,the height,the density and the species number.Based on the field investigation from the plots of natural plant communities,the diversity index,evenness index,richness index and dominance index were used to analyze the species diversity of the understory of Haloxylon persicum from the southern edge to the desert hinterland of the Guerbantongtute Desert.The results indicated that the species diversity,evenness and richness tended to decrease gradually at first and then increase,while the dominance is in reverse direction complicated.In addition,the species number of the understory ranged from 5.9 to 11.4 per square meter.The Shannon-Weiner index was from 1.034 0 to 2.097 1 and the evenness index was 0.606 8-0.876 0 per square meter.The dominance index ranged from 0.276 7 to 0.664 3 per square meter.A distance of 6.57 km far away from the southern edge was an important turning point for species diversity.The vegetation coverage varied from 14% to 36% with an obvious declining trend from the southern edge to the desert