The temporal and spatial changes of soil moisture in different density of Caragana korshinskii in sandy land of Yanchi,Ningxia

The temporal and spatial features of soil moisture of the Caragana korshinskii shrubs were analyzed.The results showed that:(1)The soil volumetric moisture in the different densities of the Caragana korshinskii shrubs changed as the soil depth changed,and the surface soil moisture was the lowest.With the increase of the soil depth,the soil moisture firstly increased and then decreased,and the variation coefficient of soil moisture gradually decreased.The vertical distribution of the soil moisture could be divided into three layers: variable speed-layer,active-layer and relatively stable-layer.(2)There were three stages for the seasonal changes of soil moisture: the accumulation stage(from April to May),the consumption stage(from June to September) and the stable stage(from October to next April).(3)The soil moisture decreased with the increase of density of Caragana korshinskii shrubs,the 2490 strains/hm2and 1665 strains/hm2 can be considered as the reference criterion to control the stand density in this area.