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).