Fig. 2. Importance of plant functional groups 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 among different steady stages.

The niche breadths of Gramineae, Cyperaceae, Leguminosae, and forbs decreased as grazing intensity increased. This succession process could also be divided into three periods. The first period was represented by “A” and “B” meadow in which the niche breadths of Gramineae, Cyperaceae, Leguminosae, and forbs were highest among all of the steady stages. The second period was the first regime shift point in which the niche breadth of Gramineae was superseded by the niche breadth of Cyperaceae (see the “C” and “D” steady stages). The third stage was the “E” stage in which the niche breadths of Gramineae, Cyperaceae, Leguminosae, and forbs all greatly decreased. In this process we also found the shrub seemed to increase with grazing intensity increasing, that was not because the steady stage underwent to the shrub meadows, just because the shrub which always used as the summer pasture had more severe degree degeneration than the alpine meadow used as the winter pasture (Fig. 3).

Overall, our findings showed that the steady stage of alpine meadows maintained the highest plant community primary production relatively constantly under no grazing intensity and under light grazing intensity. When alpine meadows were disturbed by a high grazing intensity, their total yield remained stable but the coefficient of variation in yields increased, which may indicate that change the structure of the plant community changed under these conditions to maintain a steady total biomass.