密云水库集水区防护林不同树种林冠截留研究

在充分考虑林冠结构特征与降雨特性的条件下，采用机械布样的方法，对密云集水区4种主要的防护林树种生长季的降雨再分配特点进行研究，并对4种防护林树种进行林冠截留模拟。结果表明：林内降雨量与林外降雨量呈线性相关关系，其回归系数可用来估计林冠蓄水蒸发系数，而截距可用来估计林冠蓄水容量；不同树种生长季场降雨的截留量，都表现出随降雨量的增大而增大，截留率随降雨量的增大而减少，在降雨初期，下降梯度最大，以后趋于平稳，直到饱和，各树种的理论饱和截留率在24.38％-38.42％之间；采用林冠截留模型进行模拟，林冠截留的实测值与预测值的误差均小于0.8，模型能够准确地模拟密云水库集水区防护林树种的林冠对季节性或长期降雨的总体截留能力。

Forest canopy interception of different tree species of protection forest in Miyun Reservoir watershed

Canopy structure and precipitation features,canopy rainfall redistribution during growth period of four major tree species of protection forests in Miyun watershed were studied using fixed square arrangement method.Results show that rain throughfall is linearly correlated to rainfall outside of stands,and the regression coefficient can be used to assess evaporation ability of water stored on canopy;The interceptions amount increased with rainfall amount,and the interception percentage decreased with it,dropping down quickly during initial rainfall period and then slowly and finally reaching the canopy-saturated state.The saturated interception percentage was estimated 24.38% to 38.42% by models;Simulated four stands of protection forests by interception model,the relative error between the estimation value of this model and the measured value is below 0.8.This model can forecast seasonal and long term rainfall interception of stands.