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在湖南省平江县福寿林场内,设置18块典型杉木生态公益林固定样地,对林木进行定位调查获取林木点信息。运用灰色关联度法确定林木胸径、树高和平均冠幅对林木竞争范围的影响权重,生成加权Voronoi图确定林木竞争单元,在此基础上提出更能科学反映林木竞争关系的W_V_Hegyi竞争指数,并用该竞争指数分析了杉木生态公益林优势树种杉木和其他伴生树种的种内种间竞争关系。结果表明:林木胸径、树高和平均冠幅对林木竞争范围的影响权重依次是0.38、0.29和0.33。加权Voronoi图确定的林木竞争单元中1株对象木的竞争木株数范围在2~14株,有13种可能取值。相比Hegyi竞争指数、V_Hegyi竞争指数,基于加权Voronoi图构建的W_V_Hegyi竞争指数与对象木胸径的曲线模型拟合效果更好。优势树种杉木的竞争压力主要来自于种内竞争,3个龄组(幼龄林、中龄林和近熟林)杉木树种的种内平均竞争指数分别为1.36、0.99、0.63,种间平均竞争指数分别为0.87、0.82和0.46,种内平均竞争指数分别是种间平均竞争指数的1.56、1.21和1.37倍。而其他伴生树种的竞争压力主要来自于种间竞争,但由于这些树种所占的比例较小,对整个杉木生态公益林林分的竞争态势影响不大。
In Fushou Forest Farm, Pingjiang County, Hunan Province, 18 typical plots of ecological non-commercial forests were set up, and the forest trees were located to obtain the information of forest trees. Gray relational degree method was used to determine the influence weight of tree diameter, tree height and average crown on the competition scope of forest trees. The weighted Voronoi diagram was used to determine forest competition units. Based on this, a competition index W_V_Hegyi which could reflect the competition of forest trees scientifically was proposed. The competition index analyzed the interspecific competition among the dominant species of Chinese fir forest and other associated species. The results showed that the influence weights of DBH, tree height and average crown on the competition range were 0.38,0.29 and 0.33. The number of competing woods in a wood of one wood in competition units determined by weighted Voronoi diagram ranged from 2 to 14, with 13 possible values. Compared with Hegyi competition index, V_Hegyi competition index, W_V_Hegyi competition index constructed based on weighted Voronoi diagram and curve model of woody DBH of object, the fitting effect is better. The competitive pressures of dominant species of Chinese fir mainly come from intraspecific competition. The average intraspecific competition index of three species of Chinese fir (young, middle-aged and near-mature forests) was 1.36, 0.99 and 0.63, respectively. The average competition among species The indices were 0.87, 0.82 and 0.46, respectively. The average intra-species competition index was 1.56, 1.21 and 1.37 times the average inter-species competition index. However, the competition pressure of other associated species mainly comes from interspecific competition, but due to the small proportion of these species, the competition status of the whole Chinese fir forest is not significant.