安西极旱荒漠国家级自然保护区裸果木种群结构和空间分布格局研究

Population structure and spatial distribution pattern of Gymnocarpos przewalskii in Anxi extra-arid desert national nature reserve

选择安西极旱荒漠国家级自然保护区南片的长山子、磨菇台和北片的西大泉裸果木种群为研究对象,通过样方调查,从径级结构、冠幅结构、高度结构分析了不同生境下裸果木种群的结构特征,运用扩散系数、丛生指数、负二项参数、平均拥挤度指数、聚块性指数和聚集指数判定裸果木种群的空间分布格局类型.结果表明:裸果木种群的径级结构和高度级结构均近似呈山峰型,冠幅结构近似倒J型;长山子和西大泉种群以中龄个体为主,幼龄个体和老龄个体均较少,蘑菇台种群以幼龄个体为主,中龄个体次之,老龄个体最少;蘑菇台和西大泉种群空间分布格局呈聚集型,长山子种群分布呈随机型.

The population structures of Gymnocarpos przewalskii in Changshanzi,Mogutai and Xidaquan,which are distributed in the southern and northern parts of Anxi extra-arid desert national nature reserve,were analyzed respectively from the perspectives of diameter-class,height-class and width-class structures.The spatial distribution pattern was explored using the dispersal index,index of clumping,parameter of negative binominal,index of mean crowding,index of patchiness and index of aggregation.The results showed that the diameter,height and crown class structure of Gymnocarpos przewalskii population in different habitats were approximately in the single-peak type and reversed J-type respectively.Most middle-aged individuals predominated in Changshanzi and Xidaquan population while the number of young and old individuals was smaller,and in the Mogutai population the number of the young was larger,followed by the middle-aged and the old individuals.The spatial distribution patterns of the populations in Mogutai and Xidaquan were of the aggregative type and in Changshanzi of the random type with a small aggregative degree.