常绿阔叶林是浙江省天目山国家级自然保护区重点保护植被类型，研究常绿阔叶林优势种群及其空间分布格局，可正确认识优势种群在常绿阔叶林中的地位和作用，为常绿阔叶林的保护和恢复重建提供理论依据。在天目山国家级自然保护区内，选择典型常绿阔叶林设置样地，样地大小100 m×100 m。用全站仪测定每株树木坐标。用优势度分析法确定群落优势种。采用Ripley’s K(d)函数分析优势种群空间分布格局和种间关联关系。结果表明， 常绿阔叶林的优势树种数随大小级的增大而增加，但优势树种的聚集程度却降低。常绿灌木连蕊茶(Camellia fraterna)在幼苗、幼树中占绝对优势。在中树和大树中，以细叶青冈(Cyclobalanopsis gracilis)、青冈(Cyclobalanopsis glauca)和短尾柯(Lithocarpus brevicaudatus)为主，形成多优势种结构特征。连蕊茶、细叶青冈和青冈具有较稳定的显著聚集分布特征。豹皮樟(Litsea coreana var. sinensis)和短尾柯的分布格局波动较大。从整体上看，5个优势种群的分布格局都呈显著聚集分布特征。连蕊茶与细叶青冈、短尾柯、豹皮樟，以及细叶青冈与短尾柯、青冈与豹皮樟都有较强的物种空间依赖性。青冈和短尾柯相互独立生长，有显著负关联性。同科、属的细叶青冈和青冈也表现出显著负关联性。研究认为，种间关联关系具有传递性，可以从已知3个种的两对种间关联关系推出第三对种间关联关系。已知种间关联关系越显著，且尺度范围越宽，那么种间关联关系传递的稳定性也越高。结果认为，常绿阔叶树种是天目山国家级自然保护区常绿阔叶林群落的优势种，优势种均呈显著聚集分布，多数优势种间有较强的种间关联性。
Background and Aims Evergreen broadleaved forest is an important vegetation type in Tianmu Mountain National Nature Reserve of Tianmu Mountain, Zhejiang Province. Study of dominant plant populations and their spatial patterns can reveal the roles of these populations and provide a theoretical basis for forest protection and restoration.
Methods A typical plot of 100 m×100 m was surveyed and dominance index analysis was applied to determine dominant plant populations. Ripley’s K(d) function was applied to diagnose spatial patterns and spatial associations between species pairs.
Key Results The number of dominant tree species increases with size class, but the degree of aggregation decreases. The evergreen shrub Camellia fraterna dominates seedling and small tree size class. Cyclobalanopsis gracilis, Cyclobalanopsis glauca and Lithocarpus brevicaudatus dominate mid_ and large_tree classes and have structural characteristics of multi_dominant tree species. Camellia fraterna, Cyclobalanopsis gracilis and Cyclobalanopsis glauca have stable and significant aggregated spatial patterns. Spatial patterns of Litsea coreana var.sinensis and Lithocarpus brevicaudatus vary greatly. In general, the five dominant populations have aggregated distributions. Camellia fraterna and Cyclobalanopsis gracilis or Lithocarpus brevicaudatus or Litsea coreana var.sinensis, Cyclobalanopsis gracilis and Lithocarpus brevicaudatus, and Cyclobalan opsis glauca and Litsea coreana var. sinensis, are significantly spatially independent of each other. Cyclobalanopsis glauca and Lithocarpus brevicaudatus are negatively associated with each other, so are Cyclobalanopsis gracilis and Cyclobalanopsis glauca. The association between species pairs is transferable, in that the association of the third species pairs can be deduced from the known association of two species pairs in three species; the more significant the association of species pairs and the wider the distance scale, the more stable the transference is.
Conclusions The dominant evergreen broadleaved tree species in Tianmu Mountain National Nature Reserve are significantly aggregated, and most are strongly associated.