Abstract: To reveal the variation of vegetation characteristics during the enclosure restoration of degraded vegetation in Horqin Sandy Land, we investigated the vegetation characteristics in mobile dune, semi-fixed dune, fixed dune, and sandy grassland after grazing exclusion, in midAugust of 2011, 2013 and 2015. The results showed that during 2011-2015, the dominance of dominant species Agriophyllum squarrosum in mobile dunes was gradually decreased, while that of the dominant species Artemisia halodendrom in semi-fixed dunes undulately decreased and that of therophytes increased. The dominance of therophytes was decreased and the perennials increased in fixed dunes and grasslands. Along with enclosure restoration, vegetation cover, species richness, litter biomass, aboveground biomass and belowground biomass were significantly increased. During 2011-2015, the mean litter biomass in the four habitats and the vegetation coverage in semi-fixed dunes were significantly increased, while species richness and aboveground biomass were changed undulately and there was no significant difference in the belowground biomass among the three years. Vegetaion coverage, aboveground biomass, litter biomass, belowground biomass and total plant biomass were positively related to species richness during the enclosure restoration. Changes of plant community composition and dominant species reflected a positive succession of plant community and complication of community structure, which could be predicted by a positive linear model between species diversity and biomass.

Key words: ecological risk, landslide disaster, risk, ecosystem service, vulnerability