论文部分内容阅读
以冀北山地杨桦次生林为对象，以参照树与周围最近4株相邻木为空间结构单元，以林木年轮宽度确定直径生长，研究大小比数与直径生长的关系。结果表明：该林分林木间在10～20a竞争最为激烈，是对林分进行森林经营管理、调整林分密度的最佳时期。林木大小比数的形成主要取决于林木最初生长状况以及林木的竞争能力；3个大小比数木生长优势比较，优势木生长优势明显，中庸木对劣态木无明显的生长优势；林木优势度越低，其直径生长与外界环境条件的相关性越低。“,”Taking the secondary poplar-birch forest in the mountains of north Hebei as test objects,the ref-erence tree and 4 closest neighboring trees as the spatial structure unit,the width of the tree ring is used for determining the diameter growth to study the relationship between neighborhood comparison and diam-eter growth.The results show that the most competitive time of the forest trees is 10 ~20a,which is the best time to manage the forest stand and readjust the density.The reason for formation of Betula platyphyl-la neighborhood comparison mainly depends on the conditions of the forest growth at its early stage and their competitive ability.Compared with the three neighborhood comparisons,the dominant trees grow bet-ter,the middle trees have no obvious growth advantage to the bad state trees.The lower the advantage of the trees is,the lower the relationship between diameter growth and external environment condition is.