西藏砂生槐种群结构与点格局分析

以雅鲁藏布江中游砂生槐种群为研究对象，采用相邻格子法分别在半固定沙地和固定沙地设立20 m×30 m的样方，通过对不同生境条件下种群年龄结构、空间分布格局以及不同径级空间关联等方面的研究，探讨了砂生槐种群结构与空间格局及其影响因素。结果表明，半固定沙地和固定沙地砂生槐种群年龄结构与种群（总和）特征基本一致，均呈基部宽、顶部狭，随径级增大个体数减少的趋势。砂生槐种群中幼龄体的空间分布呈明显的集群分布，随着年龄等级的增加，由中幼龄体不同尺度下的集群和随机分布交替出现过渡到大龄等级下的随机分布。半固定沙地砂生槐种群不同径级的空间关系有正相关和不相关两种方式，变化趋势是随着径级差距的加大，幼体与其他径级砂生槐的空间正相关性逐渐减弱；固定沙地砂生槐种群不同径级的空间关系均呈正相关。

Population Structure and Point Pattern of Sophora moorcroftiana in Tibet Plateau,China

Sophora moorcroftiana population in adjacent quadrats with size of 20 m×30 m on semi-fixed sandy land and fixed sandy land in the middle reaches of Yarlung Zangbo river was investigated, and the position, height and diameter at breast height (DBH) of each individual in the community were measured. The life history characteristics and spatial patterns of Sophora moorcroftiana were studied based on age class structure, spatial distribution and spatial association of different DBH classes. Results show that the age class structures of Sophora moorcroftiana on the semi-fixed sandy land and fixed sandy land are similar to the total population, that is, "wide at the base, slender at the crown, and the individual numbers reduce as the DBH class increases". The Sophora moorcroftiana population presents aggregation distribution for young trees, and aggregation intensity of Sophora moorcroftiana declines gradually with population growing, and the distribution pattern of adult trees tends to be random. The spatial association on the semi-fixed sandy land includes the positive correlation and independent pattern, and the spatially positive correlation decreases as the DBH class increases. There is a spatially positive association for Sophora moorcroftiana of all DBH classes on the fixed sandy land.