兴安落叶松与白桦混交林合理经营密度研究

为确定兴安落叶松与白桦混交林的合理经营密度，运用半峰宽原理计算小、中、大不同径级的林分合理经营密度。结果表明:1）利用胸径与冠幅的相关关系，拟合发现白桦以线性函数效果最好，而兴安落叶松以二次函数效果最好。2）建立不同径级层林分的最大密度模型，通过拟合发现各径级胸径与最大林分密度以指数函数效果最佳。3）通过半峰宽公式计算出小、中、大径级层林分合理经营密度区间分别为0.434~1.336、0.725~2.057 N_max和0.645~1.469 N_max，最小到最大合理经营密度株数配比在5∶3∶2、6∶3∶1、7∶2∶1等比例之间变化。

Rational Operating Density of Mixed Forest of Larix gmelinii and Betula platyphlla

In order to determine the reasonable management density of mixed forest of Larix gmelinii and Betula platyphlla,the principle of peak width at half height was adopted to calculate the reasonable management densities of the stands with different diameter classes (small,medium,and large).The results showed that 1)by using the correlationship between the diameter at breast height (DBH) and crown width,linear function was suitable to simulate B.platyphlla,while quadratic function was the best choice to simulate L.gmelinii.2) The maximum density models for the stands with different diameter classes were established.It was found by simulation that exponential function was most suitable.3) The reasonable management densities of the stands with different diameter classes that were calculated by the formula of peak width at half height for small diameter class ranged from 0.403-1.336 N_max,0.725-2.057 N_max for medium diameter class,and 0.645-1.469 N_max for large diameter class.The proportions between the small-,medium-,and large-diameter trees varied among 7∶2∶1,6∶3∶1,and 5∶3∶2.