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运用直径分布和空间结构参数混交度、大小比数和角尺度,分析了木兰围场4hm2天然杨-桦次生林的空间结构.结果表明:天然杨-桦次生林林分径级结构呈反“J”型曲线;林分平均混交度为0.4,其弱度和零度混交比例达51.6%,山杨、白桦的平均混交度分别为0.25和0.39;以胸径、树高为参数的大小比数基本一致,显示山杨、白桦处于亚优势向中庸的过渡状态;林分水平分布格局与树木起测直径密切相关,当起测直径为1cm≤DBH<6cm时,林分呈聚集分布,当起测直径DBH≥6cm时,林分呈随机分布.
The spatial structure of 4hm2 natural poplar-birch secondary forest in Mulan paddy field was analyzed by means of the diameter distribution and the spatial structure parameters of mixed degree, size ratio and angular scale.The results showed that the diameter structure of the natural poplar-birch secondary forest was inverse "J The average mixing degree of stand was 0.4, the ratio of weakness to zero mixed was 51.6%, and the average mixed degree of Populus simonii and Betula platyphylla was 0.25 and 0.39 respectively. The ratio of size to diameter was the same The results showed that Populus davidiana and Betula platyphylla are in the transition from subdominant to moderate. The distribution pattern of stand level is closely related to the measured diameter of trees. When the measured diameter is 1cm≤DBH <6cm, the stands are aggregated and distributed, DBH ≥ 6cm, the stands were randomly distributed.