关键词: 草地植被, 沙漠化过程, 群落演替, 土壤理化特性, 呼伦贝尔沙地, 内蒙古

Abstract: A field investigation on vegetation difference and change properties among different kinds of sand lands was conducted in the Qingbarhu Banner, Hulunbeir Sandy Land of Inner Mongolia in 2009 to understand desertification process and its mechanism of steppe vegetation. The results are as follows: (1) With development of desertification, the vegetation coverage, height, aboveground and underground biomass and litter yield of the steppe were sharply decreased, and the species richness, Shannon-Wiener index, Pielou evenness index and plant density were decreased in a fluctuation way; (2) Vegetation coverage, height and biomass were the most sensitive to desertification, and the response of species richness, biodiversity index and plant density to desertification was slow and lagged; (3) In desertification process, the effect of perennial high-quality forage was decreased but that of annual forbs was increased gradually in the community, the succession was gradually shifted from the community dominated by perennial gramineous plant Agropyron cristatum to the community dominated by annual gramineous and Chenopodiaceae plants, Setaria viridis+Corispermum macrocarpum; (4) In desertification process, soil coarseness, loose degree increase and decrease of soil organic matter and nutrient contents were the primary factors to cause vegetation degeneration, soil temperature and moisture content also affected the vegetation degeneration of the steppe to a certain extent, but the impact of soil bulk density and pH value on vegetation degeneration was quite low.

Key words: steppe vegetation, desertification process, community succession, soil physical and chemical properties, Hulunbeir Sandy Land, Inner Mongolia