Abstract: This paper analyes the changing characteristics of species diversity during the process of desertification in Kerqin,Inner Mongolia.Based on the frequency of species occurrence and the life form composition of species at different stages of desertification,the characteristics of species colonization and extinction are discussed. The species diversity indices show that desertification is a process of biodiversity loss.In particular, specialized species are wipped out first, rare species vanish second, and common species begin to disappear.Change in life form composition indicates that perennial herbaceous and scrubby plants are severely affected by desertification,whereas annuals and semi shrub species occur at all stages of desertification.The extinction rate of plants in this area is higher than their colonization rate.

Key words: Species diversity, Species diversity index, Species richness, Desertification, Kerqin region of Inner Mongolia, Chinese fir plantation, height-diameter model, nonlinear mixed-effect model, stand variables