祁连山林区大气降水特征与森林对降水的截留作用

Precipitation Characteristic and Interception of Forest in Qilian Mountain

通过对祁连山寺大隆林区定位站 1 975— 2 0 0 0年的降水特征与森林对降水的再分配分析 ,建立了祁连山寺大隆林区降水与温度、降水与湿度、林冠截留的关系式。该区多年平均降水量为 433 .5mm ,年变幅在 32 6 .4～ 539.7mm之间 ;降水量最大出现在夏季 ,占全年降水量的 65 .70 % ;海拔高度每升高 1 0 0m ,年降水量平均递增 4 .55 %。林区温度和湿度均与降水有较好的拟合关系。青海云杉林与祁连圆柏林林冠对大气降水的平均截留率分别为 37.5 %、 31 .7% ,灌木林的截留率平均高达 66 .5 %。青海云杉林林冠层平均截留率随着降雨量的增大逐渐减小 ,当降雨量为 1 8.67mm时 ,林冠截留量达到最大 ,为 1 4 .72mm ;青海云杉树干径流量占降水量的 0 .51 % ;当降雨量超过 1 2 .0mm时 ,才开始产生树干径流。青海云杉林枯枝落叶层对降雨的截留量随降雨量级增加而增大 ,截留率则随降雨量减小而增大 ,枯枝落叶层所具有的截留降雨和调蓄降雨作用使祁连山林区基本不发生地表径流。分析结果表明 ,祁连山林区对水源涵养和水流出山的时间调控有重要意义。

The long term precipitation characteristic and forest entrapment were studied at Sidalong station,Qilian Mountains. The annual average precipitation is 433.6 mm(from 1972 to 2000), and varied from 326.4 mm to 539.7 mm, annual precipitation falls in summer is 65.70%. Precipitation is altered in different altitudes, its tendency increase 4.45% of the amount with altitude arising per 100 m.The average entrapmentrates are 37.5%, 31.7% on canopy entrapping precipitation of Picea crassifolia forest and Sabina Przewalsskii forest,the average entrapmentrate of brush forest even is as high as 66.5%. When the rainfall is intensive, its average entrapmentrate gradually diminished in Picea Crassifolia forest. When the amount of precipitation is 18.67 mm, the amount of canopy entrapment of Picea Crassifolia forest is 14.72 mm. The trunk runoff of Picea crassifolia is 0.51% of the amount of precipitation and its trunk runoff began when the amount of precipitation is over 12.0 mm. The litter entrapment precipitation gradually increased when amount of rainfall increased, the entrapment rate increased when the amount of rainfall diminished.