Changes in Soil Particles Fraction and Its Spatial Variation Characteristics in Restoration Processes of Sandy Desertification Land

Soil on 6 communities in different restoration stage were sampled in a sandy desertified region,and the soil particles fraction were determined.The results showed that,soil in severely sandy desertified land is mainly constituted by 0.25~0.10 mm fine sand and 0.50~0.25 mm middle sand,the contents of which are 77.62% and 19.02%,respectively,while the 0.10~0.05 mm very fine sand and 0.05 mm silt and clay are low with contents of 1.65% and 1.67%,respectively.This characteristics indicated that soil particles were strongly divided and selected by wind in sandy desertification,making soil more and more coarse.Changes of soil particles fraction in restoration process are mainly that,the contents of very fine sand,silt and clay are increasing,while the fine sand and middle sand decreasing prominently,with the restoration degree increasing.With the effects that enhancing soil agglomeration,making the ability of soil to endure wind erosion strong,and making soil as substrate more stable,very fine sand,silt and clay are the indicator of favorable development of soil-vegetation system in restoration process of sandy desertification land.