天目山常绿阔叶林空间结构动态变化特征

采用固定样地重复监测的方法，2005-2015年每5年1次对天目山国家级自然保护区内1hm²常绿阔叶林固定样地进行3次样地调查，按优势度分析法确定群落优势树种，根据树种类别将优势树种分为常绿阔叶树种、常绿针叶树种和落叶阔叶树种3个优势树种组，利用聚集指数、树种多样性混交度和Hegyi竞争指数3个空间结构指数，分析群落和优势树种在2005-2015年期间的空间结构动态变化特征。结果表明：（1）群落表现为低度聚集、中度混交和中度竞争状态。群落聚集程度和竞争强度降低，混交程度保持稳定。群落空间结构动态变化总体特征是混交度稳定性最高，其次是分布格局，竞争态势稳定性最低。（2）群落优势种组成变化不大，3个优势树种组均呈低度聚集分布；常绿阔叶树种表现为低度混交、中度竞争状态；常绿针叶和落叶阔叶树种均表现为中度混交、低度竞争状态。常绿阔叶树种的聚集程度和竞争强度降低，混交程度保持稳定，与群落空间结构动态变化特征基本一致。常绿针叶和落叶阔叶树种的3种空间结构均保持稳定。在常绿阔叶林经营或人工林近自然改造过程中，应重视群落和优势树种的空间结构变化规律，确定阶段性空间结构优化目标，逐步促进群落进展演替。

Analysis on spatial structure dynamic characteristics of evergreen broad-leaved forest in Tianmu Mountain

In order to analyze the spatial structure dynamic characteristics of the evergreen broad-leaved forest in Tianmu Mountain, a permanent sample plot (1 hm²) in Tianmu Mountain National Nature Reserve was surveyed every 5 years from 2005 to 2015. Based on the filed data collected from these three surveys, dominance index analysis was applied to determine the dominant tree species. For easy analysis, the dominant tree species were divided into three dominant species groups: evergreen broad-leaved species, evergreen conifer species, and deciduous broad-leaved species. Then, spatial structure parameters such as aggregation index, tree species diversity mingling, Hegyi competition index were used to analyze the spatial structure dynamic characteristics of the whole community and dominant tree species during 2005-2015. The results showed that: (1) the spatial structure of community was characterized by low-level aggregation, moderate mingling and moderate competition. The degree of aggregation and competition decreased, whereas the mingling degree remained stable. And the dynamic change overall characteristics of community spatial structure were as follows: the stability of mingling degree was the highest, followed by distribution pattern, and competitive situation was the lowest. (2) The composition of dominant tree species in community did not change significantly. Three dominant species groups all represented a low-level aggregated distribution pattern. Furthermore, evergreen broad-leaved species showed a low degree of mingling and moderate competition. Both evergreen conifer species and deciduous broad-leaved species showed a moderate mingling degree and low-level competition. The spatial structure dynamic characteristics of evergreen broad-leaves species was that the degree of aggregation and competition decreased, and mingling degree remained stable. It was basically consistent with the spatial structure dynamic characteristics of community. But, the spatial structure of evergreen conifer species and deciduous broad-leaved species had remained stable from 2005 to 2015. During the management of evergreen broad-leaved forest or the close-to-nature transformation management of plantation, attention should be paid to the dynamic characteristic of spatial structure of community and dominant tree species and determine the staged spatial structure optimization goals to gradually promote community succession. At present, there are few studies on dynamic monitoring of evergreen broad-leaved forest spatial structure. In the future, the establishment of a permanent sample plot network of evergreen broad-leaved forest with spatial structure as the goal will play an important role in understanding the relationship between structure and function of evergreen broad-leaved forest, revealing the formation mechanism and succession law of community.