Soil moisture is the most important factor in the field of vegetation’s growth in arid and semi-arid regions. In regions where rainfall as the main source of soil water, precipitation, rainfall intensity, rainfall frequency and temperature are the main factors to affect the soil moisture. 

Soil moisture dynamics under the Salix gordejevii shrubs canopy on semi-fixed dune of Horqin in Sandy Land were monitored with Diviner 2000 after a rainfall (65.9mm). The result showed that during 0.5 day after the rainfall, the soil moisture at 0-90cm depth increased obviously, and the infiltration depth at shrub base (110cm) was deeper than that under shrub canopy (90cm) and the open space (100cm), the change rates of the water storage at 0-20cm and 0-80cm soil layer under shrubs were 0.88mm•d^-1 and 2.64mm•d^-1 respectively, which was slower than that in the open space (0.90mm•d^-1 and 2.88mm•d^-1, respectively), indicating that the water retention ability at these two soil layers were higher than that in the open space.  

The increase of soil water storage at 80-120cm layer at shrub base was 12.20mm, which was significantly higher than that under shrub canopy (8.79mm) and in the open space (7.29mm) during 7.5 d. With the shrubs canopy scaling up, the soil water retention ability at 0-80cm layer under shrub canopy increased, while the rainfall infiltration ability decreased. 

This program is financially supported by the National Natural Science Foundation of China (30970471), National Science Technology Support Project (2011SAC07B02), and Young Talents Foundation Program (Y251951001). This paper has been published on the Journal of Arid Land Resources and Environment, Vol. 27, No. 12, Dec. 2013.