中文摘要：

森林对降水的影响，森林与流域年径流总量的关系是两个长期以来一直存有争议的问题。本文结合国内外几十年来在此领域的研究材料对上述问题做了重新探索、研究。研究结论指出：森林若处在迎风坡上降水起始高度与降水终止高度之间时，森林具备增雨功能，但是否表现出增流取决于降水贡献损耗平衡值；森林一般不会改变降水区域总的降水量，只是改变了降水在降雨区的雨量分布情况；研究尺度的大小因区域特殊性对研究结果产生重要影响等一系列新视角、全方位的分析结论。并提出降水贡献损耗平衡值，流域面积增流功能最佳显现区间T值（[a，b]），降水终止线，区域等降水量曲线等一系列表述水文现象的新概念。

英文摘要：

The impact of forest on precipitation and relationship between forest and annual rainfall have long been two disputable issues. Based on the reseaech both at home and abroad in recent decades ,this paper rediscusse the above problems in new visual angle and aspect. It showed that forest has the function of increasing rainfall if it is growing in a facing wing gradient between the height where rain begins and the height where rain disappears, however, whether fo：est can increase precipitation depends on the balance point between the forest＇s contribution and loss fcr the rainfall ;forest usually cannot change the total amount of rainfall in a raining region, while it just changes the spatial distribution of the rainfall in a raining region ;studying areas in different scales had also made different impacts on the results, and so on. The authors also put forward some new conceptions to describe phenomenon of hydrology, for example, the balance point between the dorest＇s contribution and loss for rainfall ,the best range T（[ a ,b ] ） to show the impact on increasing the amount of rainfall in different watershed areas ,the height of rainfall disappering,the curves of regional rainfall.