从土壤物理性质、土壤蓄水量、土壤入渗、地表径流和土壤侵蚀方面研究了北京山区密云水库上游油松等林分调节水分的效应。研究表明，油松等林分具有明显的改善土壤物理性质、增加林地蓄水量和入渗量、减少地表产流的作用，根据坡面和流域对比试验的观测资料可知，所研究的林分具有明显的调洪作用和减少土壤侵蚀等效益． The effects of Pinus tabulaeformis and other stands on water regulation in the upper reaches of Miyun Reservoir in Beijing mountainous areas were studied from the aspects of soil physical properties, soil water storage, soil infiltration, surface runoff and soil erosion. The results showed that Pinus tabulaeformis and other forest stands significantly improved the physical properties of the soil, increased water storage and infiltration capacity of forest land, and reduced the effect of surface runoff. Based on the observation data of the comparative experiments on slope surface and catchment, Has obvious flood control effect and reduce soil erosion and other benefits.