中文摘要：

采用点格局分析方法对浑善达克沙地南缘不同密度下天然榆树种群的空间分布格局进行了研究,研究结果表明：1）榆树的生长指标随密度的增加有减小的趋势,当密度大于27株/hm2时天然榆树的各项生长指标趋于稳定;2）浑善达克沙地天然榆树种群空间分布格局在低密度下和中密度下随尺度的变化不大,在所有尺度下主要趋于集群分布,个别样方（样方5）呈随机分布,不同密度下榆树种群均出现最大聚集强度,并且最大聚集强度随榆树密度增加而减小的趋势明显;高密度下天然榆树的分布格局与空间尺度关系密切,在空间尺度小于临界值（23m或28m）时,榆树种群的空间分布格局趋于随机分布,当空间尺度大于临界值时,树种群空间分布格局则为明显的集群分布。

英文摘要：

We studied the spatial distribution pattern of elm population at southern edge of the Otindag Sandy Land by the method of point pattern analysis.The results show that：（1）The growth index of elm decreases with the increase of the density,and when the density of elm population is more than 27 per hectare the growth index of natural elm does not change significantly;（2）The spatial distribution pattern does not change significantly with scale when the elm population under the low-density and under the mid-density.In all scales the spatial distribution pattern of the elm population tends to clumped,just quadrat 5 tended to random distribution.The elm population suffers from the largest gathering strength when under different density,and the largest gathering strength decreases with the increase of the density.Their spatial distribution pattern is closely related to the spatial scale when the elm population under the high-density,when the spatial scale is less than the critical value of 23m or 28m,the elm population tends to random distribution pattern,and it tends to cluster spatial pattern of distribution when the spatial scale exceeds a certain critical value.