Fig. 1. Aboveground biomass of plant functional groups (PFGs) in mini-patches at various steady stages
Note: A, B, C, D, and E represent Gramineae–Kobresia meadow and Gramineae–K. humilis to K. pygmaea transitional meadow; healthy and thickening mattic epipedon in K. pygmaeameadow; cracking mattic epipedon in K. pygmaea meadow; eroded mattic epipedon in K. pygmaea meadow and black-soil beach meadow, respectively; a, b, c, d represent significance of each biomass of PFG among different steady stages.
The importance of plant functional groups in mini-patches could reflect their ability of resource obtaining positions in the plant community. The importence of Gramineae, Cyperaceae and Leguminosae gradually decreased, that of forbs gradually increased, and shrub kept in a relative stabilization under increasing grazing intensity. The trends in plant functional groups differed and could be divided into three successional periods by estimating the importance in each mini-patch. In the first period, which was under zero or light grazing intensity, Gramineae dominated and the structure of the alpine meadows was that of a grazing climax community. The second period was a transition period in which Cyperaceae was dominance. The third stage was the black-soil beach stage in which Gramineae and Cyperaceae were minor groups and forbs became the dominant group in the plant community, and during this process the Leguminosae had the analogous reaction to Gramineae (Fig. 2).