Abstract: Heaving grazing is regarded as one of the main reasons of soil degradation and desertification in the semiarid Horqin sandy grassland of northeastern China. Exclosure can control the destruction of livestock to vegetation-soil system effectively and contribute to improve the restoration of degraded ecological system. Desertified grassland, which was overgrazing, was taken as control for objection. Soil physicochemical properties were examined and analyzed the effect of exclosure on carbon sequestration potential under continuous grazing and exclusion of livestock for 13 years in desertified grassland. It was found that, after exclosure for 13 years, it had lower sand contents and higher silt and clay contents at all depths, especially for silt, which increased by 123%. The soil bulk density was lower at all five depths. Mean soil organic matter, total nitrogen, available N, available K contents increased by 102%, 97%, 123% and 24%, respectively, while available P and slowly available K went down. Soil pH increased significantly. Cation exchange capacity (CEC) went up. Except for available Fe, the mean available Cu, Mn and Zn increased by 44%, 30% and 82%, respectively. Soil organic matter was significantly positively correlated with total N, pH, CEC, available N, K, Cu, Mn, Zn (P<0.05). To a depth of 100 cm, soil carbon stock increased 393.45 g·m^-2 and carbon sequestration rate was 30.27 g C·m^-2·a^-1 after exclosure of desertified grassland for 13 years. The research shows that livestock exclusion can improve soil organic matter, nutrients and microelements and the change of soil texture and carbon sequestration potential. While the recovery of serious desertified grassland needs a long process to be raised, carbon stock is needed to restore the non-desertified grassland standard at least centenary temporal scale.

Key words: Horqin Sandy Land, grazing exclosure, sandy grassland, soil physicochemical properties, carbon sequestration potential