典型中亚热带天然阔叶林各林层林木高径比分布规律

Distribution Law of Tree Height-to-Diameter Ratio in Each Stratum of Typical Natural Broad-Leaved Forest in Mid-Subtropical Zone

【目的】揭示典型中亚热带天然阔林各林层(包括全林和各亚层)林木高径比分布规律,为中亚热带人工阔叶林、半天然林和天然阔叶林可持续经营提供阔叶林木高径比方面的典型参照。【方法】以建瓯万木林省级自然保护区为研究区,在研究区内5个典型中亚热带天然阔叶林中分别设置50 m×50 m样地,计算典型林分各林层林木高径比平均值和标准差分析其随亚层的变化情况,运用Mann-Whitney U检验分析各亚层之间(包括第Ⅰ亚层、第Ⅱ亚层和第Ⅲ亚层间以及受光层和非受光层间)林木高径比平均值的差异显著性,利用偏度和峰度描述各林层林木高径比分布的偏离程度和离散程度,选择正态分布、Weibull分布函数对各样地各林层林木高径比分布进行拟合,并采用χ^(2)检验法检验拟合效果。【结果】综合5块样地林木高径比平均值,全林为103.1,各亚层平均值随亚层高度升高而减小,排序为第Ⅲ亚层(112.7)>第Ⅱ亚层(89.0)>第Ⅰ亚层(66.9)以及非受光层(112.7)>受光层(78.3);除4号样地第Ⅱ亚层与第Ⅲ亚层间林木高径比平均值为显著差异外,其他样地内各亚层间林木高径比平均值均为极显著差异。偏度结果表明,各林层林木高径比分布为右偏。峰度结果表明,全林、第Ⅰ亚层林木高径比分布相对较为分散;第Ⅱ亚层、第Ⅲ亚层、受光层林木高径比分布相对较为集中。运用正态分布函数拟合各林层林木高径比分布,其结果均通过卡方检验;而运用Weibull分布函数拟合较多未通过卡方检验。【结论】典型中亚热带天然阔叶林各亚层林木高径比平均值间均有极显著差异,且各亚层林木高径比平均值随亚层高度升高而减小;各林层林木高径比分布均为右偏,全林与第Ⅰ亚层林木高径比分布相对较为分散,第Ⅱ亚层与第Ⅲ亚层以及受光层林木高径比分布相对较为集中;正态分布函数对各林层林木高径比分布拟合效果较好,Weibull分布函数拟合效果不理想;典型中亚热带天然阔叶林林木高径比分布与直径分布不同,全林和第Ⅲ亚层林木高径比呈正态分布,而全林和第Ⅲ亚层直径呈反J形分布。本研究所体现的各林层林木高径比平均值和各林层林木高径比分布属于理想结构森林的林木高径比特征。

【Objective】To reveal the distribution law of tree height-to-diameter ratio in each stratum of typical natural broad-leaved forest in mid-subtropical zone,to provide a typical reference in the aspect of height-to-diameter ratio of broad-leaved trees for the sustainable management of artificial broad-leaved forest,semi-natural broad-leaved forest and natural broad-leaved forest in mid-subtropical zone.【Method】In Jian’ou Wanmulin provincial nature reserve,50 m×50 m plots were set up in 5 typical natural broad-leaved forest in mid-subtropical zonerespectively.Themean tree height-to-diameter ratio and standard deviation of each stratum in the typical stand was calculated to analyze its changes with the stratum,and the Mann-Whitney U test was used to analyze the significance test of the difference between the average height-to-diameter ratio in each stratum.Skewness and kurtosis are used to describe the degree of deviation and dispersion of the height-to-diameter ratio distribution.The normal distribution and Weibull distribution function were selected to fit the distribution of the height-to-diameter ratio of each stratum in each plots,and the fitting effect was tested byχ^(2) test.【Result】The mean tree height-to-diameter ratio in 5 sample plots was integrated,the mean tree height-to-diameter ratio of the whole stand was 103.1,and the mean tree height-to-diameter ratio of each stratum decreased with the increase of the stratum height.The order and value were as follows:the stratumⅢ(112.7)>the stratumⅡ(89.0)>stratumⅠ(66.9)and NLRS(112.7)>LRS(78.3).The mean tree height-to-diameter ratio between the stratumⅡand stratumⅢin plot 4 was significantly different,and the average height to diameter ratio of trees between stratum in other plots was extremely significant.The results of skewness showed that the tree height-to-diameter ratio of each stratum was skewed to the right.The variation of skewness of the tree height-to-diameter ratio in each stratum was irregular.The normal distribution function was used to fit the distribution of tree height-to-diameter ratio of each stratum,and all the results passed the Chi-square test.However,most of the results of Weibull distribution function did not pass the Chi-square test.【Conclusion】In the typical natural broad-leaved forest of the mid-subtropical zone,the tree mean height-to-diameter ratio of each stratum has an extremely significant difference,and the tree mean height-to-diameter ratio decreases with the increase of the stratum height.The distribution of tree height-to-diameter ratio in each stratum was right skewed.The tree height-to-diameter ratio of the whole stand and the stratumⅠwas relatively dispersed,while the stratumⅡand stratumⅢwere relatively concentrated.The fitting effect of normal distribution function on tree height-to-diameter ratio of each stratum was good,but the fitting effect of Weibull distribution function was not ideal.In the typical natural broad-leaved forest of the mid-subtropical zone,the height-to-diameter ratio distribution was significantly different from that of diameter distribution.The height-to-diameter ratio distribution of the whole forest and the stratumⅢwas normal,but the diameter distribution of the whole forest and the stratumⅢwas inverted J.The average height/diameter ratio in each stratum and the distribution of height/diameter ratio in each stratum reflected in this study belong to the height/diameter ratio characteristics under ideal circumstances.