Allocation of soil organic carbon in physical fractions was measured in mobile sand dune,and stabilized sand dune usingPinus sylvestris var.Mongolica(22year forest land)andCaragana microphylla(24year shrub land)in Horqin sandy land.Results show that(1)the contents of coarse sand,very fine sand andclay+silt,and electric conductivity increased while fine sand content and soil bulk density decre-ased in woodland, compared with mobile sand dune,(2)the whole SOC storage increased by 729% with an increment of 357g/m² in forest land,and by 1050% with an increment 514g/m² in shrub land,(3)dry organic mattersin light fractions account for 0.08%,1.24% and 1.14% of the total soil weights,while carbon storages inlight fractions are 9.7,182.5 and 185.9g/m²,accounting for 20%,45%and 33% of whole SOCs in themobile sand dune,forest land, and shrub land,respectively,(4)the allocations of SOC in particle-size fractions were in orders as fine sand>coarse sand>very fine sand>clay+ silt for the mobile sand dune,coarsesand>fine sand>very fine sand>clay+silt for the forest land,and coarse sand>very fine sand>fine sand> clay+silt for the shrub land,and(5)the variations of light fraction carbon were more sensitive than thewhole SOC after sand dune stabilization.Also,the increase of unprotected organic matter within coarse sandfraction played an important role in the change of whole SOC.