Abstract: In this paper,the change and mechanism of vegetation in sandy grassland in Horqin Sandy Land during the natural regeneration process was studied.The study was carried out at Ulan'aodu in Horqin Sandy Land.The results are as follows:(1) Vegetation density and species richness in the fenced grassland were obviously improved,and the dominant species of plant community were changed obviously.The indexes of Simpson and ShannonWiener species diversity were decreased with the increase of fenced time,whereas the Pielou evenness was increased at firstly,and then decreased with the increase of fenced period; (2) Nutrient content in topsoil (0-10 cm) in the fenced grassland was increased,but the electric conductivity was decreased at firstly,and then increased with the vegetation regeneration process.Soil moisture content was decreased with fenced time; (3) Effects of topsoil factors on the plant species diversity were different.There was a significant negative correlation (P<0.05) between total N and the pH value and Pielou diversity index,but a positive one between total N and richness index.The correlations between soil factors and diversity indices were not so significant.Therefore,fencing in sandy grassland was disadvantageous for maintaining the species diversity but advantageous for accumulating soil nutrient.

Key words: fencing, sandy grassland, floristic community, soil property, soil moisture content, Horqin Sandy Land