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以六盘山南侧的华北落叶松水源涵养林为研究对象,利用标准木树干解析法,研究了21年生低、中、高3种密度(1200、1500和2000株·hm-2)华北落叶松人工林的生长过程和直径结构.结果表明:华北落叶松3种密度林分在10年生前各项生长指标差异不显著;10年生后的林木直径、单株材积和林分蓄积生长过程明显不同;21年生时,低密度林分的生长状况明显优于中、高密度林分,但树高生长受密度影响不显著;3种密度林分直径分布的偏度系数(Sk)差异较大,高密度林分的Sk(0.338)大于中密度(0.072)和低密度林分(0.015).前者直径分布偏离正态分布,呈现顶峰偏左的现象;后者的直径分布接近正态分布,密度结构较合理;中密度林分直径分布的峰度系数(K,1.691)大于高密度(1.532)和低密度林分(0.665).说明中密度林分的林木分化程度比高、低密度林分小;林龄为21年的华北落叶松人工林的合理保留密度应为1200株·hm-2.
Taking the Larix principis-rupprechtii stand on the south of Liupan Mountains as the research object, the 21-year-old low, medium and high densities (1200, 1500 and 2000 plants · hm-2) of Larix principis-rupprechtii The growth process and the diameter structure of the plantation.The results showed that there was no significant difference in the growth indexes of three kinds of density stands of Larix principis-rupprechtii before 10-year-old growth, and the growth process of the tree diameter, The growth of low-density stands was significantly better than that of medium-high-density stands at 21 years of age, but the growth of tree height was not significantly affected by the density. The skewness coefficients (Sk) Sk (0.338) in high-density stands was greater than that in mid-density (0.072) and low-density stands (0.015), with the former being deviated from the normal distribution and the other with a peak-left deviation. (K, 1.691) was larger than that of high-density (1.532) and low-density forest (0.665), indicating that the degree of tree differentiation was higher in middle-density forest than in low-density forest Small; Larix age 21 years of Larix principis-rupprechtii plantation reasonable reservation The density should be 1200 plants · hm-2.