大辽河流域天然杨桦林空间结构分析

Spatial Structural Characteristics of Natural Populus davidiana-Betula Platyphylla Forest in the Great Liaohe River Basin

以辽宁老秃顶子国家自然保护区内天然杨桦林为研究对象,利用混交度、胸径和树高大小比数、角尺度3个林分空间结构参数分析了林分空间结构特征。结果表明:林分平均混交度为0.62,其强度和极强度混交比例达53.1%,黄桦、山杨的平均混交度分别为0.87和0.74,表明天然杨桦林混交程度较高;以胸径、树高为参数的大小比数基本一致,表明黄桦、山杨处于优势向亚优势的过渡状态,且优势木的比例都超过70%;林分平均角尺度为0.52,黄桦和山杨的平均角尺度分别为0.54、0.55,呈聚集分布。

Taking Natural Populus davidiana-Betula allegheniensis secondary forests in the Liaoning Laotudingzi National Nature Reserve as the research object,we used the mingling degree,breast height（DBH）and heigh neighborhood comparison and the uniform angle index to analyze the spatial structural characteristics of the mixed forest.The results showed that the average mingling degree was 0.62,with the individuals at high and extremely high mingling degree reached to 53.1%,and the average mingling degree of Betula allegheniensis and Populus davidiana was 0.87and 0.74,respectively,indicating that Natural Betulaallegheniensis Populusdavidianasecondary forests was mixed with high mingling degree.The neighborhood comparison based on the diameter at DBH and tree height was almost the same,suggesting that the Betula allegheniensis and Populus davidiana were in the transition state from dominant to subdominant,and the proportion of the dominant trees were more than 70%.The average uniform angle index of the whole stand,Betula allegheniensis and Populus davidiana was 0.52,0.54and 0.55,respectively.The forest plantation presented a gathering distribution pattern and the proportion of trees that had the mingling degree reached to 53.1%.