| The agro-pastoral ecotone of North China is mainly distributed in the southern margin of Inner Mongolia Plateau and the area along the Great Wall,with an annual precipitation of 200-400 mm and a dryness of 1-2.It belongs to semi-arid ecologically fragile area.In the context that the international community pays high attention to ecologically fragile areas and China's economy enters a new normal,the agro-pastoral ecotone of North China,which shoulders important missions such as ecological barriers and balanced regional development,has ushered in historical development opportunities.However,in the agro-pastoral ecotone of North China as a typical semi-arid and dry-water-poor region,surface water resources have been basically exhausted,in the context of global climate warming.The disorderly use of water resources in the agricultural production of the agro-pastoral ecotone in North China has exacerbated the water crisis in the ecotone.Ecological problems such as grassland degradation,soil desertification,and land salinization have seriously endangered regional economic,social,and ecological sustainable development.Therefore,it is essential to discuss the path,model and layout for the sustainable development of agriculture in the ecotone from the perspective of water resource limits and realize sustainable development of economy,society and ecology in the ecotone with the premise of “zero growth” of water resources.This research was conducted through a combination of theoretical research and practical exploration.Based on a review of existing literature on the agro-pastoral ecotone in North China and field investigations of the agro-pastoral ecotone,Tongliao,as a typical representative in the agro-pastoral ecotone of North China,was selected for a case study.By analyzing characteristics of social and economic development in the agro-pastoral ecotone of North China,this research concluded that the sustainable development of agriculture determines the key point in the sustainable development of agro-pastoral ecotone in North China,and pointed out that in essence,problems in the sustainable development of the agro-pastoral ecotone in North China refer to the lack of water resources,contradictions in the production development triggered by the unreasonable water resource allocation among different regions caused by the traditional agricultural overexploitation,and ecological environment deterioration caused by the overexploitation of limited water resources in traditional agriculture.In view of this,this research took water resources as a conditional constraint,adopts the system dynamics method,and made a comprehensive simulation of 3 paths including the traditional agricultural development path,the returning-grain plots-to-forestry agricultural development path and the circular agriculture economic development path,to explore the optimal path for the sustainable development of agriculture in the agro-pastoral ecotone of North China.According to the optimal path for circular agricultural economic development,3 kinds of circular agricultural economic development models for the agriculture,husbandry and animal husbandry were built.Moreover,based on an analysis on the value and benefits of each model and in consideration of technical difficulty,economic input,development stage and other factors,the 3 kinds of circular agricultural economic development models were further divided into 6 sub-models,which are available for the selection of the agro-pastoral ecotone to develop its circular agricultural economy.To better guide the practice of regional circular agricultural development,this research took townships as the administrative unit and discussed the functional zoning of agro-pastoral space based on 3 development states(the current state,general development state and water resource constraints).Meanwhile,the circular agricultural economic development model was applied to analyzing the comprehensive layout of the circular agricultural economic model from 2 dimensions: space and time.The following conclusions were drawn in this research.First of all,the development of circular agricultural economy is the optimal path for sustainable development of agriculture in the agro-pastoral ecotone of North China.By establishing the system dynamics and analyzing the results of its operation,it can be seen that the total GDP of the circular economy at the end of the simulation period is 1.08 times and 1.95 times the traditional agricultural path and the return farmland,and the water use efficiency is 1.41 times and 1.82 times.System dynamics-based simulation research on the returning-grain plots-to-forestry economic development path and the circular economic development path showed that the circular economic development path can extend the industrial chain,achieve better economic benefits,a higher water-using efficiency,significant improvement of the ecological environment and larger absorption of the transforming rural labor,and better promote the sustainable development of the agro-pastoral ecotone of North China.Secondly,the establishment of a circular agricultural economic development model system injects new vitality into the development of circular agricultural economy in the agro-pastoral ecotone of North China.The circular agricultural economic development model system is built to change the situation that the agro-pastoral ecotone of North China has long been receiving no guidance of the circular agricultural development model and effectively promote the circular agricultural economy to exploit its advantages and values.The research shows that the per capita income of the recycling agriculture development model is 47.44% higher than the traditional agricultural development model system,the water use efficiency is increased by 80.75%,the average land use efficiency is increased by 80.96%,the total water consumption is saved by 18.43%,and the total occupied land area is saved.18.53%;both the cyclic animal husbandry and circular agriculture development models have correspondingly improved.In accordance with the principle gradual advances in the development stage and continuous enrichment of system-building contents,the circular agricultural economic development model system is further designed into several sub-models,which not only provides sufficient choices for the development of circular agricultural economy in the agro-pastoral ecotone of North China,but also adds new vitality to achieve the diverse development of the circular agricultural economy in the agro-pastoral ecotone.Thirdly,the scientific functional zoning of the agro-pastoral space is the basis for the rational distribution of the circular agricultural development model.In view of the fact of the over-developed agriculture in the agro-pastoral ecotone of North China,3 principles for evaluating the functional zoning of the agro-pastoral space,which reflect the current functional distribution of the agro-pastoral space,priority for production development and priority for ecological development,are put forward.The 3 principles are: current status,development priorities and water resource constraints.Research shows that compared with the development of priority agro-pastoral and eco-priority spatial divisions,16 and 26 townships have overexploited agriculture in the current state,accounting for 21% and 33% of the total number of townships.Under the guidance of the evaluation principles,a comprehensive study is conducted on the functional zoning of the agro-pastoral ecotone in Tongliao,to point out that agriculture of Tongliao is currently over-exploited,so it is quite essential to reverse this trend by changing the current development path.Fourthly,the comprehensive layout of the circular agricultural development model provides the endogenous driving force for the sustainable development of the agro-pastoral ecotone in North China.4 principles and methods for the comprehensive layout the circular agricultural development model are identified.And in accordance with the principles,the integrated layout method is adopted to achieve a multi-scale dynamic layout for the spatial and temporal integration of the circular agricultural development model in Tongliao and help Tongliao to achieve regional steady development with the promotion of circular economy and realize long-term development for its regional circular agricultural economy.This has provided sustained endogenous driving force for the sustainable development of the agro-pastoral ecotone in North China.Lastly,policies and suggestions for promoting the sustainable development of the agro-pastoral ecotone in North China are presented.Based on the comprehensive layout of the mode of use of circular agricultural economy and technology,this paper proposes policies and suggestions for promoting agricultural production organizations to effectively promote the sustainable development of circular agriculture.To implement circular agricultural economy,we must combine the circular economy's technological development mode with the agricultural production organization mode,use the circular economy's technical model to enrich the content of the organizational model,and use the organizational model to promote the development of the technical model and support each other.This study proposes four organizational models that are suitable for the northern agricultural and pastoral ecotones,namely family farms,cooperatives,“leading enterprises + farmer households” and ecological parks,and four kinds of organizational models. |
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