## 5 Discussion
### Prospect of Grassland Management Model in the Agro-Pastoral Ecotone  
According to the 2017 report of the Food and Agriculture organization of the United Nations on the global food crises, 108 million people faced serious food security problems in 2016 [34]. With the progress of human technology and the adjustment of dietary structure (the growing demand for meat), biofuels and livestock consumed half of the global grain. Therefore, mankind would be confronted with a new form of grain \"famine\". Grassland ecosystem was an open system. If it was artificially delineated as a closed-systems, and the entry of an external negative entropy flow was restricted, it would be unfavorable to the cycle renewal and restoration of grassland ecology. In a word, based on the above social and ecological background, the GPP urgently need to adjust the management mode, time limitation, and space category according to the vegetation restoration. [PERSON] et al. selected 2003-2015 as the reference period and used the system dynamics model to simulate the possible scenarios of grassland social-ecological systems under different ecological compensation standards in the next decade. This result showed that the GPP significantly promoted the resilience of social-ecological system. With the improvement of the compensation standard, the grassland society system became more stable, but the ecosystem resilience decreased. The compensation standard of $17.31/ha was relatively reasonable, which had the best effect on promoting the restoration of grassland social-ecosystem in the following 10 years [23]. This conclusion differed from the willingness of the LGMs who recommend higher compensation standards. The eco-compensation had nothing to do with the herdsmen's behavior and the effect of grassland protection. Therefore, the protection of grassland ecology can not only rely on the government's considerable eco-compensation, but we need to explore a more reasonable and feasible grassland management system. Is it feasible that the GPP be lifted? What will happen if the GPP stops? The survey of grazing experiments conducted by [PERSON] et al. in Dashuikeng Town in 2012 can answer the above question. This town, as the integrated pilot scheme for animal load balancing and rangeland management, implemented the grazing trial (limiting livestock based on grassland carrying capacity and seasonal grazing) in 2006. This trial covered 4146 herdsmen and 6.37 \(\times\) 10\({}^{4}\) ha land. After grazing, the whole farming scale decreased, and the difference of the grazing scale between herdsmen increased. The grazing time was shorter than the traditional free grazing. Sixty percent of the herdsmen who participated in the trial adopted the combination of pen feeding and free-grazing. The overloading phenomenon was significantly reduced, and the net income of sheep increased by 18.9%. After two years of the experiment, 48.3% of the herdsmen thought that the quality of herbage after grazing was better. At the same time, the right to the grassland contract management began to flow [35]. The pilot scheme restored the use of grazing land rights, and enhanced community participation and autonomy. It provided new ideas and experiences for the solution to the rangeland management and the dilemma of GPP. The conclusions of the grazing experiment for grassland management are: (1) Policy makers should focus on both the rangeland conservation and herdsmen's livelihoods; (2) flexible management plans and community participation mechanism, including property rights system, collective selection rules, trust and moral growth, and supervision punishment,should be developed. Therefore, the individual commitment and community management should be introduced to the market system, rather than simply the supervision and eco-compensation from governments [35]. In conclusion, the appropriate adjustment of the GPP by local authorities is correct and has a certain rationality and adaptability.