粤北常绿阔叶林乔木优势种群结构与格局动态

在粤北车八岭自然保护区内选择具有代表性的常绿阔叶林群落设置2 hm2的固定样地,应用相邻格子法进行每木调查,分析乔木层优势种群结构、分布格局及生态位特征,探讨群落结构和动态及其内在联系.结果表明:(1)该群落主要优势种为米锥Castanopsis carlesii,乔木层优势树种径级结构为"L"型,群落处于相对稳定的增长阶段;(2)结合垂直分布型结构与生态位宽度分析,可知群落中米锥、荷木Schima superba等占据资源位较多,个体数量及幼苗储备丰富,对资源的竞争力最大;鸭公青Neolitsea chuii及栓叶安息香Styrax suberifolia等次之,尾尖叶柃Eurya acuminata对资源的利用和竞争力最差;(3)应用方差均值比、Lloyd平均拥挤度和聚块指数以及负二项分布指数对优势种群进行格局分析,各种群整体格局均为集群分布,但是在不同的发育阶段,随着径阶增加,种群格局逐渐由集群分布过渡到随机分布.这既与物种本身的生态和生物学特性有关,也与外界环境有密切关系.

Structure and Distribution Patterns of Dominant Populations in an Evergreen Broadleaved Forest in North Guangdong Province

Field data were obtained by sampling contiguous grid quadrat method in the 2 hm~2 evergreen broadleaved forest permanent plot established in Chebaling National Nature Reserve,Shixing County,north Guangdong Province.Through analyses of dominant population structure,distribution pattern and niche characterislics,community dynamics and its underlying relations to the tree layer were discussed. The results indicated that 1) the most dominant tree species in the community was Castanopsis carlesii and the size-class distribution of the dominant species showed an L-shaped structure,showing that the community was in a growing and stable increasing period;2)as for the vertical distribution structure and niche breadth,it was found that Castanopsis carlesii and Schima superba,which were abundant in individuals and sapling reserves,had greater niche breadth and more superior in resource utilization.The resource utilization ability of some species including Neolitsea chuii and Styrax suberifolia were less,while Eurya acuminata was the least;and 3)the distribution pattern of dominant populations analyzed using t-test of variance to mean ratio,Lloyd's index and negative binomial parameter,were clumped as a whole.However,the distribution patterns changed from clumped into random with the time during development period,while the clumped intensity of different populations reduced gradually, which was not only closely related to ecological and biological characteristics of species, but also to its environment.