北京山杨、白桦次生林抚育间伐强度的确定方法

A Preliminary Report of Study on Thinning Strength for Secondary Forest of Aspen and Brich in Beijing

北京地区的山杨、桦木次生林,10～12年时已有明显分化,直径连年生长量9年开始下降,12年时与直径平均生长量相交,表明首次间伐应该开始。杨桦次生林的间伐强度,不宜用原始密度计算,我们用不同保留株数确定,间伐生产中保留株数,我们用改进的B.E.乌道特公式编表。

It is quite obvious that aspen and brich in the Beijing area become divided while they are 10-12 years old.The current annual increment of the tree diameter begins to decrease from the 9th year. In the 12th year the value of increment will be equal to the average increment. This means it is time for thinning. It is not reasonable to calaulate the thinning strength by original density, so it is determined by the different amounts of remaining trees. During production we check the number of remaining trees with a tabled on the improved B. E. Wodaut formula