燕山北部白桦华北落叶松次生林种群结构与动态研究

为了阐明白桦华北落叶松次生林的动态变化规律，对燕山北部白桦华北落叶松次生林种群进行了系统研究，分析了白桦和华北落叶松种群的径级结构、静态生命表、存活曲线。结果表明，燕山北部白桦和华北落叶松种群，中径级个体多，大小径级个体少，呈现衰退型趋势。从期望寿命来看，白桦种群和华北落叶松种群在Ⅱ径级时，期望寿命达到最大，表明此阶段种群生理活动达到旺盛期。随着径级的增加，白桦和华北落叶松死亡率和消失率基本呈现相同的趋势，即先降低后增加的趋势，在小径级和大径级时，其死亡率高，表明这两个种群有衰退的趋势。适当间伐白桦和华北落叶松对其次生林天然更新和恢复具有重要意义。

Study on the population structure and dynamics of Betula platyphylla and Larix principis-rupprechtii in secondary forest in the north region of Yanshan mountain

The age class,life table,survival curves and dynamics of Betula platyphylla and Larix principis-rupprechtii in secondary forest in north region of Yanshan mountain were researched systematically,The results showed that Betula platyphylla and Larix principis-rupprechtii in secondary forest in north region of Yanshan mountain reveal a declining trend with less young and less old individuals.Mean life expectancy of Betula platyphylla and Larix principis-rupprechtii populations was the highest in Ⅱ age class,indicating that the physiology activity was vigorous time.Mortality and vanishing rate of Betula platyphylla and Larix principis-rupprechtii were increased and thereafter decreased with the increase of age class and the highest mortality appears in smaller and bigger age class,which indicates that the Betula platyphylla and Larix principis-rupprechtii population would decline.Therefore,it is important to the natural renew and recovery of secondary forest to make proper intermediate cutting of Betula platyphylla and Larix principis-rupprechtii trees.