基于Voronoi图的金洞林场闽楠人工林林木种内、种间竞争的研究

A study on intraspecific and interspecific competition of Phoebe bournei plantation in Jindong Forest Farm based on Voronoi diagram

基于金洞林场闽楠人工林3块样地的数据,采用Voronoi图确定林木的空间结构单元,利用Pearson相关分析法和曲线拟合比较分析Hegyi简单竞争指数、综合竞争指数(含胸径、树高、冠幅及林木间距离因子)、剔除该模型中比对象木矮的竞争木后的Hegyi简单竞争指数和综合竞争指数,比较分析4种竞争指数的优劣,筛选出更适于描述闽楠人工林竞争机制的竞争指数。结果表明:(1)修订前与修订后的简单竞争指数和综合竞争指数都与林木胸径呈极显著负相关(P<0.01)。(2)修订后的竞争指数与胸径的Pearson相关分析法和曲线拟合均高于修订前的,即H_(m)>H、C_(m)>C;修订后的竞争指数的平均值均小于修订前的,即H平均值>H_(m)平均值、C平均值>C_(m)平均值;选取的4种林木竞争指数中,剔除该模型中比对象木矮的竞争木后的综合竞争指数是最优的。(3)利用修订后的综合竞争指数计算得出3块样地中闽楠的种内平均竞争指数分别为0.53、0.54和0.81,种间平均竞争指数分别为0.53、0.83、0.99,种内平均竞争指数比种间平均竞争指数小,闽楠的竞争压力主要来自于种间竞争。研究结果可为金洞林场闽楠人工林的合理经营与抚育间伐等措施的制定提供理论参考依据。

Based on the data from three sample plots of Phoebe bournei plantations in Jindong Forest Farm,the spatial structure of the trees was determined using Voronoi diagrams,and the Hegyi simple competition index,combined competition index(including diameter at breast height,tree height,crown width and distance factor between trees),and the Hegyi simple competition index and combined competition index were analyzed using Pearson correlation analysis and curve fitting.The Hegyi simple competition index and the combined competition index after the exclusion of competing trees,the advantages and disadvantages of the four competition indices,and the selection of competition indices that were more suitable for describing the competition mechanism of Phoebe bournei plantations.The results showed that:(1)both the pre-revised and post-revised simple competition indices and combined competition indices were negatively correlated with stand diameter at breast height.(2)The Pearson correlation analysis and fit of the post-revised competition indicing with diameter at breast height were higher than those of the pre-revised model,i.e.,H_(m)>H、C_(m)>C,the mean values of the revised competition indices were all smaller than those before the revision,i.e.,mean H>mean H_(m) and mean C>mean C_(m) and the combined competition index was the best among the four selected competition indices after excluding the competition trees that were shorter than the target trees.(3)Using the post-revised the average intra-species competition index was 0.53,0.54,and 0.81,while the average inter-species competition index was 0.53,0.83,and 0.99.The average intra-species competition index was smaller than the average inter-species competition index,and the competitive pressure on Phoebe bournei was mainly due to inter-species competition.The results of the study can provide a reference for the development of rational management and nurturing interval measures for Phoebe bournei plantations in Jindong Forest Farm.