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以广西14年生杉木和马尾松人工林为对象,设同一疏伐强度的下层疏伐、上层疏伐、机械疏伐和干扰树间伐4种处理,分别用标准差、变异系数、偏度、Gini系数、库兹涅茨系数和洛伦茨不对称系数6种指标对4种间伐方式下采伐前后林木个体大小差异进行评价.结果表明:与间伐前相比,马尾松和杉木人工林下层疏伐或上层疏伐后,林木个体材积的标准差、变异系数、Gini系数和库兹涅茨系数均变小,偏度变大;干扰树间伐后标准差、变异系数、Gini系数和库兹涅茨系数均变大,偏度则不一定.马尾松林和杉木林下层疏伐后洛伦茨不对称系数变大,上层疏伐或干扰树间伐后则变小.机械疏伐后各指标无明显变化规律.干扰树间伐后林木个体大小差异性增加,上层疏伐和下层疏伐后林木个体大小差异性减小.洛伦茨曲线、Gini系数和洛伦茨不对称系数均能较好地反映林木个体大小不一致性,可以进行不同林分间个体差异程度静态和动态比较,较好地反映不同间伐方式引起的林木个体差异.洛伦茨不对称系数可以判断林木个体大小不一致性的来源是大树还是小树.近自然森林经营中干扰树间伐措施可以在减小目标树竞争压力的同时拉大林木个体大小差距,有助于保持目标树在林分中的优势地位.
The 14-year-old Chinese fir plantations and Pinus massoniana plantations in Guangxi were selected as the study objects. Four treatments including lower layer thinning, upper layer thinning, mechanical thinning and interference tree thinning with the same thinning intensity were used. The standard deviation, coefficient of variation, skewness, Coefficient, Kuznets coefficient and Lorentz coefficient of asymmetry were used to evaluate the differences of individual size before and after cutting in four kinds of thinning methods.The results showed that compared with the pre-thinning, the thinning of Pinus massoniana and Cunninghamia lanceolata plantation After the upper thinning, the standard deviation, coefficient of variation, Gini coefficient and Kuznet’s coefficient of individual volume of forest tree became smaller and the skewness became larger. The standard deviation, coefficient of variation, Gini coefficient and Gini coefficient The coefficient is larger and the skewness is not certain.The Lorentz asymmetry coefficient of P. massoniana and Cunninghamia lanceolata after the thinning is larger and the upper thinning or disturbance tree thinning is less after the thinning.The indexes after mechanical thinning have no significant change The difference of individual size of forest tree after the intercropping of tree was increased, the difference of individual size of forest tree after upper thinning and lower thinning decreased.The Lorenz curve, Gini coefficient and Lorentz asymmetry coefficient all could reflect forest tree Individual size Which can reflect the individual differences of individual trees caused by different thinning methods.The Lorentz asymmetry coefficient can be used to judge whether the size of individual trees is the source of large tree or small The disturbance of tree thinning in near-natural forest management can widen the individual size gap of trees while reducing the competition pressure of the target tree, which helps to maintain the dominant position of the target tree in the forest stand.