三峡库区典型森林植被对降雨再分配的影响

Effect of typical forest vegetation on rainfall redistribution in the Three Gorges Reservoir

为探讨三峡库区不同森林植被对降雨再分配的影响,选择位于湖北库区中上段的巴东县、重庆库区下段的四面山、缙云山的针阔混交林和常绿阔叶林为研究对象,利用重庆市缙云山2012年4—9月期间测得的52场降雨、林内穿透雨、树干径流观测资料,建立林冠截留模型,对降雨再分配特征进行综合分析,并与巴东县和四面山的降雨再分配特征进行对比分析。结果表明:1)缙云山、四面山、巴东县的针阔混交林、常绿阔叶林林内穿透雨量与降雨量呈显著的线性关系,林冠截留量与降雨量呈显著的幂函数关系;2)缙云山、四面山、巴东县针阔混交林出现林内穿透雨所需要的最小降雨量分别为1.0、1.8和2.6 mm,常绿阔叶林出现林内穿透雨所需要的最小降雨量分别为1.1、3.0和1.1 mm;3)3个地点的针阔混交林的平均林冠截留率均大于常绿阔叶林的平均林冠截留率;4)在相同降雨条件下,林冠截留能力因地域不同,具有差异,即针阔混交林的林冠截留率从大到小的排列顺序为重庆市缙云山(46.00%)、重庆市四面山(41.42%),湖北省巴东县(22.30%),常绿阔叶林的林冠截留率由大到小的排列顺序为重庆市四面山(28.78%),重庆市缙云山(23.09%),湖北省巴东县(21.69%)。

In order to explore the effect of different forest vegetation types on rainfall redistribution in Three Gorges Reservoir area,we choose evergreen broadleaf forests and conifer-broadleaf mixed forests in the reservoir area as research objects,which are located near Badong County in the upper section of the reservoir of Hubei Province,Simian Mountain and Jinyun Mountain in the lower section of the reservoir in Chongqing.Using the observation data of rainfall,throughfall and stemflow for the 52 measured rain events in Jinyun Mountain of Chongqing from June to September in 2012,the canopy interception model was built up.Then we analyzed the characteristics of rainfall redistribution and compared the precipitation redistribution characteristics in Badong County with that in Simian Mountain.The result shows that the throughfall has a significant linear relationship with rainfall in the evergreen broadleaf forests and coniferbroadleaf mixed areas of Jinyun Mountain,Simian Mountain and Badong County.What is more,the amount of canopy interception has a significant exponential relationship with rainfall.According to the equation,the required minimum rainfalls to create throughfall in these areas for broadleaf forests are 1.0 mm,1.8 mm and 2.6 mm separately; on the other hand,it requires 1.1 mm,3.0 mm and 1.1 mm for conifer-broadleaf mixed forests in the same areas.The average interception rate of conifer-broadleat mixed forests is greater than the average entrapment rate of evergreen broadleaf forests at these locations.Under the same rainfall condition,the canopy interception rate of conifer-broadleaf mixed forests descends in the order of Jinyun Mountain in Chongqing （46.00％）,Simian Mountain （41.42％） and Badong County in Hubei Province （22.30％） ; such ranking for broadleaf forests is Simian Mountain （28.78％）,Jinyun Mountain in Chongqing （23.09％） and Badong County in Hubei Province （21.69％）.