Research On The Trade-off And Synergy Of Agricultural Ecosystem Services In Taiyuan City

Resource-based cities,as important energy bases in China,have brought serious pollution to the ecological environment in the process of resource utilization and industrial development.Agro-ecosystem services can not only provide human beings with material products,but also play a role in regulating climate and purifying the environment,which is an important asset for human survival and development.With the development of urbanization and the improvement of people's quality of life,the demand for agricultural products has increased dramatically.However,in the process of land resource utilization,human usually pay much attention to the quantity of agricultural products that land can supply,regardless of the damage caused to agro-ecosystems,which threatening the sustainable development of agro-ecosystems.In addition,In the process of agricultural production,agro-ecosystem supply service can be easily evaluated,while regulatory services and support services are usually underestimated or ignored due to slow and undetectable changes,leading to changes in trade-offs and synergies among agro-ecosystem services.Excessive fertilization and flood irrigation for agriculture have also brought serious negative impacts on agro-ecosystems,resulting in the generation of some disservice,such as soil pollution,waste of water resources and so on.Incorporating negative services of agro-ecosystem into the study of ecosystem service trade-offs and synergies,an in-depth understanding of the trade-off mechanism between the positive and negative service functions of ecosystems is an important scientific issue in current research.Furthermore,the changes of trade-offs and synergies between agro-ecosystem services are also affected by various factors,such as human interaction,natural and socio-economic factors and so on,while the research in this area is quite few,so the research on the influence mechanism of agro-ecosystem service trade-offs and synergies changes is of great importance for promoting the comprehensive assessment and effective management of agro-ecosystem services.In this thesis,taking Taiyuan,a heavy industrial city with rapid urbanization development in central China,as a research area.Firstly,on the basis of field investigation,the calculation model of ecosystem service value and the relevant theories in geography,landscape ecology,economics,etc.,the agro-ecosystem service value of Taiyuan in 2000 and 2018 were measured.Then,the trade-offs and synergies between positive and negative services were explored by means of the correlation analysis and cold hot spot analysis methods,which is of great importance on reasonable allocation of agricultural land types,promoting agricultural planting patterns and guiding famer's behaviors,avoiding or reducing the impact of agro-ecosystem negative services on the entire agro-ecosystems and promoting the sustainable development of agro-ecosystem.Finally,the drivers of trade-offs and synergies between positive and disservice functions in agro-ecosystems were explored and discussed,which is of great importance to deeply understand the trade-offs and synergies between agro-ecosystem services and the influencing factors in heavy industrial cities in central China.In conclusion,the results are as follows:(1)The total agro-ecosystem service value of Taiyuan in 2018 increased 72.01%compared with that in 2000,the growth of production function and tourism and leisure function are greater than the others,which are 575.81%?56.38%respectively.Water conservation function and carbon sequestration and oxygen release function present a downward trend,which decreased 42.85%?39.45%respectively.As for negative services,environmental pollution and water consumption services generated by agro-ecosystems have increased 293.07%and 250%.(2)The total ecosystem service value of Taiyuan is higher in the southwest and lower in the northeast,which is mainly related to the types of land utilization and the kinds of crops planted.In the east and north of the Fenhe River in Taiyuan,human interference has greater impacts on agro-ecosystems,leading to serious landscape fragmentation and relatively lower ecosystem service value,while the ecosystem service value is much higher in the western region,which is widely covered with forest and grassland and rich in biodiversity.When it comes to southern region,the ecosystem service value increases relatively fast for the development of fruit industry and vegetable planting.(3)The relationship between agricultural production function,water conservation,carbon sequestration and oxygen release remains synergistic in Taiyuan from 2000 to 2018,but their synergistic relationship has weakened.Production function and environmental purification function have always maintained a trade-off relationship.The relationship between production function,environmental pollution and water consumption function is synergistic,and the agricultural non-point source pollution and water consumption costs will aggravate with the increase of production function.The relationship between production function and tourism and leisure is transformed into a synergistic relationship.(4)The hot spot region of multiple agro-ecosystem services mainly distributed in the north and south of the urban built-up space;Secondary hot spot is mainly distributed in Loufan and Gujiao.It has an important impact on the various service functions of the agro-ecosystem with the urban expansion,transformation of agricultural structure and transformation of agricultural planting patterns,etc.,making the trade-off relationship between the functions of ecosystem services more prominent and the hot spot areas greatly reduced correspondingly.(5)The kind of land that people interfere the most is construction land,followed by cultivated land,woodland,grassland and water regions.The farther away from the city center,the smaller the influence of human interference.In addition,the degree of interference of human activity to ecosystems is closely related to terrain,economic development level,population density and national policies.(6)The changes in trade-offs and synergies of agro-ecosystem services is mainly affected by population density,primary industry output value,pesticide usage amount,grain and vegetable planting areas in heavy industrial cities in China.Among them,the increase in population has led to an increase in demand for agricultural products and tourism and leisure,so,it has shown a clear synergistic relationship between production function and tourism and leisure function for the increase in population.The output value of the primary industry and the amount of pesticides used can promote the synergistic development of carbon sequestration and oxygen release functions and water conservation functions.At the same time,excessive use of pesticides will inhibit the increase of the purification function of the agro-ecosystem environment.The increase of population density and vegetable area will lead to the expansion of agricultural pollution area and the increase of water consumption cost.