A STUDY ON THE OPTIMAL VEGETATION COVERAGE FOR SANDY GRASSLAND IN NORTHERN CHINA BASED ON SOIL WATER BUDGET
基于土壤水分平衡的沙地草地最优植被覆盖率的研究

A simple simulation model is developed for soil water dynamics on a sandy slope with different soil physical properties, different geographical locations, different aspects and slopes and different vegetation types and coverage. The model is parameterized with recent colfeeted experiment data from the target area. Conclusions are: I ) the effect of resistance to penetration of precipitation to soil by the "shell" formed on the surface soil with organic mat ters and thus runoff in most cases are neglegible compared to the evapotranspiration, except with a very steep hill; 2) variation of yearly average soil water content is affected by all the factors listed above. The effect of plant coverage is complicated by other factors such as topography(slope and aspect) and root resistance to perculation. Simple conclusion can not be drawn without specifications of all these parameters.