| The Loess Plateau is an ecologically fragile area and a vegetation restoration area in China.The coordinated and sustainable development of the ecological,economic and social systems of the region is not only an objective requirement for the implementation of the concept of green water and green mountains being the silver mountain of gold,but also a realistic demand for the construction of ecological civilisation and high-quality development.After decades of vegetation restoration,the vegetation cover of the area has reached its water-bearing limit,and the recovery of vegetation and ecological functions has entered a relatively slow stage,so the restoration of ecosystem development trends and scientific management has become a major question that needs to be answered.Moderate disturbance can,to a certain extent,reconcile the ecological environment with socio-economic conflicts and promote the coordinated and sustainable development of ecological,economic and social systems.Therefore,this study addresses the development of fallow land on the Loess Plateau,the realistic demand for sustainable management of restored ecosystems and the scientific issue of the impact of grazing disturbance on fallow restored ecosystems,takes fallow grassland as the research object,based on the theory of moderate disturbance,through field surveys and interviews with 276 farmers in 55sample plots in four types of areas,namely Ansai,Dingbian and Shenmu in Shaanxi and Guyuan in Ningxia.The research method of subjective and objective assignment method,energy value analysis and ecological-economic-social system coupling and coordination model were used to systematically study the evolution characteristics of ecological functions of fallow grassland under different grazing intensities and their trade-offs,reveal the response mechanism of farmers’livelihood capital and its sustainability to grazing intensity,assess the comprehensive effect of fallow grassland ecological-economic system under different grazing intensities,and improve the ecological-economic-social system of fallow grassland as the basis for the study.The objective is to improve the synergistic development of the ecological-economic-social system in the fallow grasslands of the Loess Plateau,and to clarify the grazing threshold for the synergistic and sustainable development of the ecological-economic-social system in the fallow grasslands of the Loess Plateau.The main conclusions are as follows:(1)Grazing intensity had a significant effect on the vegetation community characteristics of the fallow grassland,with vegetation height,cover and biomass all decreasing significantly with increasing grazing intensity.The response of ecological functions of fallow grasslands to grazing intensity showed some variability,with heavy grazing significantly reducing the multifunctionality of fallow grassland ecosystems,while light and medium grazing did not cause significant changes in ecosystem multifunctionality.The trade-offs between ecological functions of fallow grasslands under different grazing intensities are highly complex,with different grazing intensities leading to differences in the trade-offs between ecological functions.Overall,grazing can weaken the trade-offs between multiple ecological functions of fallow grassland to different degrees,and a comparison of the optimum grazing intensity from the perspective of multiple ecological function trade-offs shows that the trade-offs between multiple ecological functions of fallow grassland are the lowest and the best synergistic relationship under moderate grazing intensity(3～6.7 sheep/hm~2).(2)Grazing can increase the stock of livelihood capital of farmers,optimise the livelihood structure of farmers and enhance the sustainability of farmers’livelihoods.Overall,the natural,human,physical,financial,social,environmental and psychological capital of grazing farmers are on average 2.91%,21.51%,41.11%,86.33%,24.22%,2.12%and 43.55%higher than that of grazing farmers,respectively,and the degree of livelihood capital coupling and coordination is on average 13.35%higher.This positive effect was more pronounced at moderate grazing intensity.Grazing intensity had a significant positive effect on natural,physical and financial capital and a significant negative effect on environmental capital,while the effect on livelihood sustainability was not significant,but had a positive relationship and there may be some threshold effect.However,whether or not grazing has a significant positive effect on the livelihood sustainability of farm households,indicating that grazing can enhance the livelihood sustainability of farm households.Therefore,it is realistic and feasible to increase the livelihood capital stock of farming households,optimise their livelihood structure and improve their earning capacity through moderate grazing.(3)Under different grazing intensities,the proportion of auxiliary energy inputs is much larger than that of environmental resources,and all of them are mainly electricity and fertiliser inputs,while renewable organic energy inputs are mainly labour inputs.Of the total energy inputs,42.82%of the energy value of non-renewable resources is greater for the no-grazing farmers than for the grazing farmers,indicating that the no-grazing farmers are more dependent on non-renewable resources than the grazing farmers’development system.In terms of system energy output,the highest energy output for crops and livestock was found under heavy grazing intensity,while the highest energy output for ecosystem service functions was found under light grazing intensity.The energy value indicators of the different grazing intensity systems show that the production and management model under light grazing intensity(<3 sheep/hm~2)is better than the other grazing intensities in terms of labour productivity and sustainability due to the rational use of ecological resources and labour.(4)Under different grazing intensities,the development of the ecological,economic and social systems of the fallow grassland differed significantly,with the overall development index of the fallow grassland ecosystem being on average 20.55%lower than that of the grazing ban,while the overall index of the economic and social systems was on average 70.85%and 2.24%higher,respectively.The coupling coordination tends to increase and then decrease with increasing grazing intensity,with light and moderate grazing intensity increasing by 11.15%and 8.12%respectively compared to grazing prohibition,while heavy grazing intensity decreases by 5.18%.On the whole,the type of coupled coordination of the ecological-economic-social system of fallow grasslands with different grazing intensities has gone through a progression from barely coordinated development to intermediate coordinated development and then to primary coordinated development and on the verge of dysfunctional decline.The barrier factor of coupled coordination increases with grazing intensity,and changes from economic and social factors to ecological factors.The light grazing intensity is the most suitable grazing intensity to achieve the ecological-economic-social coupled sustainable development of the fallow grassland on the Loess Plateau.This study systematically investigates the effects of grazing disturbance on the evolution of ecological functions,livelihoods and sustainability of farmers and the ecological and economic effects of restored ecosystems on the Loess Plateau,and,based on the perspective of coupled ecological-economic-social systems and with the objective of improving the synergy of ecological-economic-social systems of restored ecosystems,defines grazing thresholds for the synergistic and sustainable development of the ecological-economic-social systems of fallow grasslands on the Loess Plateau.This study provides a theoretical basis and practical reference for the appropriate use of retired grassland resources,the sustainable management of restored ecosystems and the integrated development of“ecological-production-living”in the region. |
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