青海云杉林冠截留特征研究

运用统计建模的方法，系统研究了青海云杉（Picea crassifolia）林冠截留与降水、林分郁闭度间的关系。构建包含林分郁闭度因子的改进模型，通过模拟认为，复合模型I=a（1－e^-PC）＋bPC模拟精度高，参数物理意义较明确，其中参数a（1.3627）代表了林冠吸附容量系数，b（0.1835）代表了区域的降雨蒸发系数，较好地解释了青海云杉林冠截留吸附、湿润与蒸发物理过程的机理。分析表明，青海云杉林冠截留率随降水的变化曲线可分为快变期（完满郁闭度截留率大于36.1％，降水小于5mm）、渐变期（完满郁闭度截留率36.1％～20.40％，降水5～25mm）和稳定期（完满郁闭度截留率小于20.4％，降水大于25mm）3个阶段，完满郁闭度林冠稳定截留率为20.4％，反映了青海云杉树冠几何形态特征与截留特征间的关系。观测期间青海云杉现实林分林冠截留率平均值为19.36％～23.96％，完满郁闭度林分截留率的平均值为25.67％。青海云杉树干次茎流率均低于0.1％，平均为0.0182％，树冠的几何形态结构（枝叶的分布与排列）不利于形成树干茎流。

Study on Forest Interception of Picea crassifolia

The relationships of forest interception with rainfall and canopy density have been studied by modeling.It was concluded that the forest interception of Picea crassifolia could be simulated precisely by the compound model of I=a(1-e~(-PC)) bPC which including canopy density factors. The parameter a(1.362 7)means rainfall adsorption capacity of canopy, and parameter b(0.183 5)means coefficient of evaporation of canopy regionally, all this explain the law of forest interception which composed of 3 physical courses:adsorption,soakage and evaporation. It was indicated too that the curve of forest interception with rainfall marked 3 phase such as descent quickly phase(interception rate of fall canopy density stands is more than 36.1% while rainfall is less than 25mm),descent gradually phase (interception rate is in 36.1 .4% while rainfall is in 5~25 mm)and stable phase(interception rate is less than 20.4% while rainfall is more than 25mm),which explain the relationships of interception with canopy geometry shapecharacteristics of Picea crassifolia. The mean interception rate of imperfect stands in periods of investigation is in 19.36%~23.96%,but that attend to 25.67% for perfect stands with fall canopy density. The stemflow is less than 0.1% and the mean value is less than 0.018 2% for the special geometry shape construction of canopy go against stemflow.