Soil moisture of Robinia pseudoacacia stands in the Loess area in West of Shanxi Province

According to the location observation in two years,the change rule of soil water in Robinia pseudoacacia stands were studied,and influence factors to soil moisture were discussed.It was showed that Robinia pseudoacacia is the most resisting drought tree in Loess area.So Robinia pseudoacacia stands and its mixed stand can be planted on south of hill,top of mountain and eastern of hill.When the density of Robinia pseudoacacia stand is less than 2 250 trees per hectare,soil moisture of stands can be supplemented at the end of growth season.When the density of Robinia pseudoacacia stands are more than 2 250 trees per hectare,soil moisture of stands can not be supplement at the end of growth season,so growth of trees are limited.Furthermore by quantificational analysis of the influence factors of soil water,it was showed that rainfall of month,evaporation,humidity of month,density of stand,and biomass are the major meteorologic and vegetation factors.