密云水库上游水源保护林试验示范区土壤水分动态初步研究

通过定位观测和对比试验，对密云水库上游水源保护林试验示范区土壤水分的动态变化规律进行了初步研究．结果表明，试验区内土壤水分年动态变化主要决定于降雨量的大小和降雨的年内分配，与降水的年动态变化非常一致，与蒸发量的年动态变化相反．１９９６年土壤水分动态可分为：雨季前土壤水分缓慢蒸发期、雨季湿润期、雨季后逐渐降低稳定期；１９９７年的土壤水分动态可分为：雨季前土壤水分蒸发期、雨季湿润期、雨季后期干旱期、冬春土壤水分缓慢升高稳定期．下坡的土壤含水量显著大于上坡的土壤含水量，同一坡向的有林地比无林地的土壤含水量高．不同坡向土壤含水量由大到小的顺序是：有林地西坡、有林地东坡、无林地北坡、无林地南坡．林地涵养水源的效应非常明显

Preliminary Study on Soil Moisture Dynamics in the Experimental Area of Water Conservation Forest in the Upper Stream of Miyun Reservoir

By means of site measurement and comparison this paper presents the preliminary research advances on the soil moisture dynamics in the experimental area of water conservation forest in the watershed of Miyun reservoir. The results show that the yearly soil water dynamic patterns are well corresponded with that of rainfall distributions while contrasted with that of evaporation. In the year of 1996, soil moisture pattern can be divided into three periods: progressive evaporation before rainy season, wetting period in the rainy season, and progressive decrease approaching stability. In the year of 1997, it can be divided into four periods: evaporation stage before rainy season, wetting stage during rainy season, drying stage post rainy season, and slow increasing to the stability in the winter. Soil moisture content in the lower part of the slope is greater than that of the upper part. Soil moisture in the forested slope is much greater than that of no tree one with the same aspect. The soil moisture status of the monitored sites in the order of decreasing are as follows: forested west facing, forested east facing, no tree north facing, and no tree south facing slope. It is implied that forest has good potential of soil conservation.