雅鲁藏布江中游干旱沙地砂生槐种群结构与点格局分析

砂生槐（Sophora moorcroftiana）是雅鲁藏布江中游干旱河谷区植被群落的重要建群种，具有极强的耐瘠薄、抗风沙等生态适应性和防风固沙、保持水土功能。为了揭示砂生槐种群的结构、生长特征和空间分布规律，运用大小级组成和Ripley’s K函数分别研究了砂生槐的种群结构和空间点格局，发现砂生槐个体主要集中在中等大小（冠幅40～80 cm，高度20～40 cm）范围，幼苗期成活率较低，中等个体抗逆和生存能力较强。砂生槐种群的发展演替过程可以概括为：少数个体集群性定居→在原有聚集尺度范围繁殖→种群改良局部环境，密度增大，种内竞争加剧→种群向更大尺度扩散和壮大，演替进入顶极阶段。砂生槐种群各大小级都呈现以9 m左右尺度斑块状聚集分布的特征，在实地生态恢复过程中应遵循其生长和自然分布规律，人工栽培中应重点注意冠幅＜20 cm、高度＜13 cm阶段幼苗的抚育，另外应首先选择土质等条件相对优越的小生境种成适当规模的集群分布形式，充分发挥其防风沙的能力、提高栽培成活率和固沙效率。

Population Structure and Spatial Point Pattern of Sophora moorcroftiana in Arid Sandy Land in the Middle Reaches of Yarlung Zangbo River, Tibet

Sophora moorcroftiana, which has a strong tolerance ability to blown sand and soil impoverishment and a potential value of sand fixation and soil conservation, is the constructive species of the arid valley vegetation community in middle reaches of the Yarlung Zangbo River. To explore the population structure, growth characteristics and spatial distribution pattern, size classes statistics and Ripleys K function are used to study the population structure and spatial pattern of S. moorcroftiana respectively. The results are as follows. (1) Majority of the S. moorcroftiana population are medium-size individuals because the survival rate of seedlings is low, in contrast, adverse resistance and survivability of medium-size individuals are powerful. (2) Successional process of S. moorcroftiana population follows an order: a few individuals invade-the population multiply-habitats are improved and population density increases to induce excessive competition-the population expand spatially and succession enters the climax phase. (3) The individuals of S. moorcroftiana of different size classes are all aggregated on a scale of 9 m. It is suggested that in breeding of S. moorcroftiana people should pay more attention to the seedlings with the crown width less than 20 cm or the height less than 13 cm and choose relatively superior habit to cultivate large population to boost survival rate, so as to make full use of its abilities of windbreak and sand-fixation.