关键词: 草原, 沙漠化, 植被演替

Abstract: The middle east part of Ningxia Hui Autonomous Region is located in the transitional zone between warm steppe and desert steppe on loess plateau,Under the influences of dry and windy climate,loose sandy surface and improper economic activities of mankind,the area has become one of the most serious desertified land in Ningxia.Although the succession stage of desertified steppe vegetation is of ten difficult to judge,we successfully distinguished the vegetation into two groups and four phases by means of cluster analytical methcds. The vegetational succession of desertified steppe was different from those of sandy land vegetation and abandoned field vegetation. Cynanchum komarovii and Peganum nigellastrum are indicator plants in the beginning and the development phases of desertified steppe vegetational succession. The key step to turn the disertified vegetation into steppe vegetation is to strictly control human activities.

Key words: Steppe desertification, Vegetation succession