No abstract

Kobresia meadows are the main pastures for animal husbandry on the Qinghai–Tibet Plateau, and may represent alternative steady states associated with different grazing intensities. The ability of other plant communities to succeed these meadows remains unclear. In this study, the historical data of plant communities were analyzed in terms of the soil profile, and the present characteristics were identified by investigating their plant communities. Four types of steady states were identified, corresponding to grazing intensities of >11, 8–11, 5.5–8, and < 5.5 sheep/ha. Drought alpine swamp meadows and shrub meadows could succeed to K. pygmaea meadows and K. humilis meadows under overgrazing, and their total biomass and edible biomass (estimated by Gramineae and Cyperaceae) decreased with increasing grazing intensity. The regime shift of the states occurred at a grazing intensity of 8–11 sheep/ha. This value thus represented the threshold of significant change in the production and ecological service function in the Kobresia meadow succession process. In general, increasing grazing intensities can adversely affect the service ability of meadows for livestock production and ecosystem stabilization. This study revealed the potential degraded succession process of the alpine Kobresia meadow and the succession direction in the restoration process of degraded meadows. Additionally, this study provided a theoretical basis for evaluating the fitness between the livestock bearing capacity and carrying capacity in steady states and academic reference for policy setting pertaining to the utilization of Kobresia meadows in a sustainable development framework.

Mini-patches are considered indicators of an ecosystem’s response to interference, particularly those in alpine meadow ecosystems. Thus, monitoring the characteristics of mini-patches can elucidate the organization of an ecosystem’s components, the strategies it employs to survive interference, and the mechanisms whereby it maintains stability. In this research, we used multivariate statistical analysis methods to investigate the characteristics of the plant community and the micro-topography of mini-patches in alpine meadows on the Qinghai-Tibet Plateau from August 2012 to August 2013. Our findings show that (1) mini-patches were distributed in alpine meadows with different levels of degradation and the effects of meteorological characteristics (accumulated temperature above 0°C and accumulation of precipitation) and geographical characteristics (altitude, longitude, and latitude) contributed less than 20% to their distribution and characteristics; (2) alpine meadows maintained aboveground biomass within a certain range under a relative larger range of grazing intensity, illustrating their ability to regulate community structure and components under various intensities of disturbance and showing that alpine degradation could itself counteract grazing disturbance; and (3) overgrazing is the main driver of multi-steady stage coexistence in alpine meadows, as the mini-patches that remain involved in plant community succession function, and as a source of germplasm in the plant community regime shift under different grazing intensities damaged alpine meadows.