大兴安岭落叶松天然次生林林分结构特征

为了探明大兴安岭地区天然次生林林分结构现状并对其做出准确合理的评价,以新林林业局落叶松天然次生林5块典型样地的调查数据为基础,综合考虑不同林分类型和树种配置比例,利用威布尔分布函数(Weibull)和角尺度、混交度、大小比数3个林分空间结构参数对落叶松天然次生林的水平结构及空间结构进行综合分析。结果表明:落叶松天然次生林种群类型较单一,伴生树种比例少,直径分布形状呈现左偏或右偏多峰山形,各样地Weibull形状参数由大到小为:样地3(2.324)、样地1(2.264)、样地5(2.059)、样地4(1.969)、样地2(1.925);各样地树种混交度较小,空间隔离程度较弱,由大到小为样地4(0.358 1)、样地5(0.242 9)、样地2(0.237)、样地3(0.173 1)、样地1(0.081);林木大小比数分布较为均匀,林分中优势、亚优势和中庸状态分布的个体比例相差不大,由大到小为样地2(0.526)、样地3(0.495 2)、样地1(0.491 9)、样地4(0.486 5)、样地5(0.471 4);5块样地角尺度平均值为0.515,林木聚集程度较低,整体分布格局属于随机分布。因此,大兴安岭地区落叶松天然次生林林分结构存在着一定的不合理性,树种组成过于简单,径阶分布较为集中,空间隔离程度偏低,为提高林区整体生态效益,应制定相应的补植改造、抚育间伐调整措施,使林分结构趋于合理。

Forest Structure Characteristics of Larix Natural Secondary Forest in Daxing'an Mountains

We studied the Daxing'an Mountains of natural secondary forest structure situation and made precise and reasonable evaluation on the survey data,with Larch natural forest of five typical plots of Xinlin Forestry Bureau and the comprehen-sive consideration of different forest types and species proportion.We used Weibull distribution function(Weibull)to ana-lyze the level of structure and space structure and angle scale,mixed degree,ratio of three stand spatial structure parame-ters of Larch forest.The Larix natural secondary forest group type was relatively single, the forest had small proportion of associated tree species and diameter distribution showed the shape of left or right side of peak,the Weibull shape parame-ters of various sample plots were:sample 3(3.09)>sample 1(2.846 1)>sample 4(2.251 6)>sample 5(2.083 2)>sam-ple 2(1.939).All of the mingling intensity were small and the degree of spatial segregation was weak,in particular:sam-ple 4(0.358 1)>sample 5(0.242 9)>sample 2(0.237)>sample 3(0.173 1)>sample 1(0.081).The neighborhood com-parison distributed evenly and the individual proportion of stability,advantages,advantages and the sub state distribution was not significant,in particular:sample 2(0.526)>sample 3(0.495 2)>sample 1(0.491 9)>sample 4(0.486 5)>sam-ple 5(0.471 4).The average neighborhood pattern of five plots was 0.515,indicating that the forest accumulation process, the aggregation degree of forest trees was low and the overall distribution pattern was random distribution.Therefore, the Larix natural secondary forest structure was certain unreasonable in Daxing'an Mountains Mountains,species composition was too simple,the diameter distribution was more concentrated,the isolation degree of space was low,to improve the effi-ciency of ecological forest,appropriate measures of replanting transformation and plantation thinning should be drawn up.