A study on the effect of soil moisture of different vegetations in Loess Hilly Region

Based on data collected by system soil moisture survey and random survey in Loess Hilly Region,in this paper,authors had analyzed systemically soil moisture status of different vegetation land in many sits with rainfall ranges from 400~580 mm.The research showed that the soil moisture profile was different.The order was that farm landpasture landshrub community landarboreal forest.Sometimes,the soil moisture of arboreal forest may be higher than that of shrub land because of the lower productivity and plant density of the community.In extreme drought period,soil water extracted,and then decreased to a low degree,therefore gap in the soil moisture of different type vegetations reduced,even vanished.The vegetations exempt crop could bring a dry soil layer in the soil profile.The soil moisture in more rainfall region where acacia could grow normally was better than that of lower rainfall regions where arboreal forests growing were restricted by soil water supply.So some water protection methods need to be put in to practice in order to prompt plantgrowing.