闽楠天然次生林林分空间结构研究

A Study on the Spatial Structure of Natural Secondary Phoebe bournei Forest

以闽楠天然次生林为研究对象,通过12块标准地调查获取数据,运用混交度、大小比数和角尺度分析林分空间结构特征,并采用林分空间结构评价指数将其划分为5个评价等级。结果表明：（1）林分平均混交度为0.525,林木为强度混交;平均大小比数为0.506,林木分化属于中庸向劣态过渡状态;平均角尺度为0.518,林木呈聚集分布。（2）林分空间结构评价指数值为0.08～0.89,与理想的空间结构差距较大;仅5号标准地评价等级最高（Ⅴ级）,其表现为林木混交程度高,林木大小分化不明显,分布格局为随机分布,闽楠为主要优势树种,在林木竞争上占有优势地位,是较理想的空间结构模式。研究结果可为优化闽楠天然次生林空间结构经营措施的制定提供参考。

Taking the natural secondary Phoebe bournei forest as the research object,data were collected through investigating 12 sample plots.The indices of mingling degree,neighborhood comparison and uniform angle index were used to analyze the characteristics of spatial structure.According to the evaluation index of spatial structure,it was divided into 5 levels.The results showed that：（ 1） The average mingling degree was 0.525,which was intensive mingling; the average neighborhood comparison was 0. 506,which was in the state from middle to inferior; the average uniform angle index was 0. 518,which was an aggregate distribution.（ 2） The range of evaluation indices of the spatial structure in the standard sample plots were from 0.08 to 0.89,which had great discrepancy with ideal spatial structure; only the level of No.5 standard sample plot was the highest（ level Ⅴ）,and the mingling degree of the trees was also high; the sizes of the stands showed no distinctive difference,and its distribution pattern was random.Further more,Phoebe bournei was the dominant tree species,which had advantages in competition.All of these elements composed ideal spatial structure.The research results could provide reference for taking management measures for optimizing spatial structure of natural secondary Phoebe bournei forest.