Abstract:

The study was conducted at Inner Mongolia Grassland Ecosystem Research Station of the Chinese Academy of Sciences in Xilingol Region, 43°20′-44°00′N，116°06′ -117°05′E. The goal of the study was to provide some scientificbasis for the restoration of degenerated grassland. Many statistical methods were used to study the succession laws of degenerated steppe of Leymus chinensis after shallow ploughing. After the data over a period of 18 years were analyzed, the results showed that the method of shallow ploughing could improve community density in degenerated steppe of L. chinensis due to overgrazing. The index of diversity and homogeneity of plant species resulted in a open-up parabola for 18 years. The relative density reached maximum at the fifth year, then gradually decreased. It tended to horizon since the fifteenth year. The important value of L. chinensis appeared open-down parabola. The process of community succession can be divided into four stages. The first stage was a community of L. chinensis+annual and biennial synusia (1-3 years after shallow ploughing). The constructive synusia was rhizome grass. Dominant synusia were annual and biennial synusia. The second stage was a community of L. chinensis(4-9 years after shallow ploughing). The constructive synusia was rhizome grass. Dominant synusia were thick grass and rhizome Carex. The third stage was a transition community of L. chinensis+Agropyron michnoi+rosette grasses(10-13 years after shallow ploughing). The constructive synusia was rhizome grass. Dominant synusia were short thick grass and rosette grass. The fourth stage was a community of L. chinensis+A. michnoi, thick grasses, rosette grasses (14-18 years after shallow ploughing). The constructive synusia was rhizome grass. Dominant synusia were thick grass and rosette grass. Through 18 years of restoration, the degenerated steppe was different from the primary communities of L. chinensis. Therefore, it is predicted that succession will continue until a stable community establishes.