基于加权Voronoi图的杉木生态公益林空间结构量化分析

Quantitative analysis of stand spatial structure of Cunninghamia lanceolata non-commercial forest based on weighted Voronoi diagram

以湖南省福寿国有林场内24年生杉木生态公益林为研究对象,通过胸径加权Voronoi图确定各中心木的邻近木,计算混交度、大小比数、聚集指数、林层指数和开敞度5个空间结构指数,全面分析了该林分的空间结构特征。结果表明:1)林分平均混交度为0.21,为弱度混交,树种空间隔离程度较低;2)林分平均大小比数为0.58,林分胸径大小分化不太明显,处于中等竞争状态;3)林分平均聚集指数为1.06,林木总体上处于由均匀分布向随机分布演替的过渡阶段;4)林分平均林层指数为0.24,林木在垂直空间上配置较为简单;5)林分平均开敞度为0.23,林木生长空间不足。

To analyze the spatial structure of the Cunninghamia lanceolata non-commercial forest, the plantation predominanted by the 24-year-old C. lanceolata located in Fushou State-owned Forest Farm of Yueyang City, Hunan Province of China was taken as the study object, and five structural parameters, i. e. mingling degree, neighborhood comparison, aggregation index, storey index and open degree, were calculated based on the DBH weighted Voronoi diagram that can determine the reference tree＇s neighborhood groups of trees. The results showed that： 1） the average mingling degree of stand was 0.21, indicating the simple spatial allocation and poor mixing of different tree species; 2） the average neighborhood comparison of stand was 0.58, and the differentiation of DBH was not significant, which meant a middle level of competition; 3） the average aggregation index of stand was 1.06. The individuals of tree presented the succession trend from uniform distribution to random distribution; 4） the average storey index of stand was 0.24, and the spatial configuration was relatively simple in the vertical space; 5） the average open degree of stand was 0.23, thus, the stand was relatively crowded and hadn＇t adequate growing spaces.