新疆阿尔泰山地天然针叶林林分空间结构特征

阿尔泰山地分布的以西伯利亚落叶松、西伯利亚云杉和西伯利亚红松为主要树种组成的天然针叶林，是我国典型的西西伯利亚山地南泰加林的代表。利用角尺度，混交度和大小比数3个林分空间结构参数分析阿尔泰山地天然针叶林空间结构特征。结果表明：(1) 林分角尺度均值为0.509，表明阿尔泰山地天然针叶林的林分总体呈随机分布格局；随着林木直径的增大，分布格局模式为“随机分布—团状分布—随机分布”；(2) 林分的平均混交度为0.629，属于由不同树种组成的中强度混交，西伯利亚云杉混交度最小，且随着林木径阶的增加，混交度呈逐渐增加的趋势；(3) 西伯利亚冷杉和西伯利亚落叶松在林分中具有明显优势的地位，而西伯利亚红松处于劣态。随着林木胸径的增大，林木的大小比数逐渐减小，大小分化却由小径木的劣态转到中径木的优势地位，再到大径木的绝对优势地位。在阿尔泰天然针叶林经营中，可以考虑把大径阶的西伯利亚落叶松作为采伐木，达到优化林分结构的目的。

Stand spatial structure of natural coniferous forest in the Altai Mountains of Xinjiang

Natural coniferous forest in the Altai Mountains in Xinjiang province is a typical forest type of the southern taiga, which is mainly composed of Larix sibirica, Picea obovata and Pinus sibirica. Parameters of stand structure such as neighborhood pattern, mingling degree, and neighborhood comparison were used to analyze the spatial structure of the natural coniferous forest in the Altai Mountains. The results were as follows. (1) Stand mean neighborhood pattern was 0.509, which indicated that the stand was randomly distributed. With the increase of tree diameter, its distribution pattern changed from random distribution to cluster distribution, and then to random distribution. (2) The average value of mingling degree was 0.629, indicating that different tree species were intensively mingled. The mingling degree of P. obovata was the lowest and it gradually increased with the increase of the diameter classes. (3) Abies sibirica and L. sibirica possessed a more dominant position than P. sibirica in the stand. It was observed that neighborhood comparison decreased with the increase of tree diameter. So, in order to optimize the structure of the stand, L. sibirica of large diameter class should be used as cutting wood in managing the natural coniferous forest in the Altai Mountains.