Effects of continuous grazing and livestock exclusion on soil properties in a degraded Mu Us sandy grassland,Inner Mongolia,northern China

Overgrazing by domestic livestock has greatly degraded many arid and semiarid grassland ecosystems around the world,and it does in the Mu Us sandy grassland.Exclusion has been applied as a main measure for revegetation all over the world,which may be an effective,financially economical and natural way to restore.In this paper,we examined three grazing management treatments: continuous year-long livestock grazing(grazing),grazing excluded for 5 years(5-yr exclosure) and grazing excluded for 16 years(15-yr exclosure),analyzed the effects of grazing exclusion on soil physical and chemical properties.The results as follows: The 5-yr exclosure had no discernible influence on soil particle size distribution and bulk density in 0～30 cm soil layer as compared with continuous grazing.The 16-yr exclosure increased the proportion of very fine sand(0.1-0.05mm),silt(0.05-0.002mm) and clay( 0.002mm),and decreased bulk density in 0～10 cm.The 5-yr exclosure enhanced soil organic carbon concentration(SOC) in 0～5 cm,and had no effect on total nitrogen accumulation in 0～30 cm.SOC increased significantly by 231%,81% and 55%,respectively,in the 0-5,5-10 and 10-30cm soil layers in 16-yr exclosure as compared with grazing treatment.The 16-yr exclosure effects on total N followed the same trend as SOC.The results suggested that soil chemical and physical properties can be improved with the implementation of protecting from grazing.