川西亚高山红桦-岷江冷杉林优势种群的空间格局分析

以红桦-岷江冷杉林4 hm²样地调查数据为基础，采用点格局分析法O-ring函数，分析了红桦和岷江冷杉2个优势种群不同龄级的空间分布格局，以及各龄级间的种内和种间关联性.结果表明：红桦种群径级分布呈单峰型，为衰退种群;岷江冷杉种群径级分布呈倒“J”型，为进展种群.岷江冷杉与红桦大树在所有尺度上均为随机分布，其余龄级在小尺度上为聚集分布，随尺度增大趋于随机分布和均匀分布，最大聚集强度随龄级增大而减弱.空间关联主要发生在小尺度上.岷江冷杉种内关联以小尺度正关联为主，红桦种内关联以小尺度负关联为主.对于2个种群的相同龄级，小龄级、中龄级和大龄级间，分别以空间无关联、负关联和无关联为主.2个种群间不同龄级间以负关联为主，龄级相差越大，其负关联越强.

Spatial patterns of dominant tree species in sub-alpine Betula-Abies forest in West Sichuan of China.

Based on the investigation in a 4 hm2 Betula-Abies forest plot in sub-alpine area in West Sichuan of China, and by using point pattern analysi s method in terms of O-ring statistics, the spatial patterns of dominant specie s Betula albo-sinensis and Abies faxoniana in different age classes in study ar ea were analyzed, and the intra- and inter-species associations between these age classes were studied. B. albo-sinensis had a unimodal distribution of i ts DBH frequency, indicating a declining population, while A. faxoniana had a reverse J-shaped pattern, showing an increasing population. All the big trees of B. albo-sinensis and A. faxoniana were spatially in random at all s cales, while the medium age and small trees were spatially clumped at small scal es and tended to be randomly or evenly distributed with increasing spatial scale . The maximum aggregation degree decreased with increasing age class. Spatial as sociation mainly occurred at small scales. A. faxoniana generally showed pos itive intra-specific association, while B. albo-sinensis generally showed negative intra-specific association. For the two populations, big and small tre es had no significant spatial association, but middle age trees had negative spa tial association. Negative inter-specific associations of the two populations w ere commonly found in different age classes. The larger the difference of age cl ass, the stronger the negative inter-specific association.