| As an important part of ecological construction,farmland ecosystem ensures the good operation of farmland ecosystem and is the basis for ensuring food security.The rapid urbanization of metropolitan areas has affected and destroyed the balance of farmland ecosystems in metropolitan areas,affected farmland production capacity and ecological service functions,and restricted regional food security and ecosystem construction.Therefore,the research on the function and service value of farmland ecosystem is of great significance to strengthen the production capacity and function of farmland ecosystem and build the pattern of farmland ecological security.Based on the principle of multi-dimensional and multi-angle analysis,this paper uses the analytic hierarchy method,ecological service value equivalent factor method,expert scoring method and other methods to carry out a comprehensive ecological evaluation of the farmland system from the aspects of ecological function,ecological service and farmland safety pattern,systematically analyzes the multifunctional characteristics and key influencing factors of the farmland ecosystem in the metropolitan area,and puts forward suggestions and measures for the sustainable development of the farmland ecosystem in Chengdu.The main results are as follows:(1)The primary productivity,water purification and regulation,carbon sequestration capacity,biodiversity and farmland nutrient supply function indices of Chengdu’s farmland system were 63.47～92.58,60.99～96.81,62.24～93.75,74.38～95.10 and 60.95～97.98,respectively,which were at the middle and upper levels,but the different needs of each function made the supply and demand of some functions unbalanced.The supply of water purification and regulation,biodiversity,and farmland nutrients in Chengdu’s farmland system basically meet the demand,while the supply function of primary productivity and carbon sequestration capacity has an imbalance between supply and demand.The areas with imbalance between supply and demand of primary productivity functions are mainly distributed in Jintang and Jianyang in the east;The imbalance between supply and demand of carbon sequestration capacity is mainly distributed in Pengzhou,Xindu,Jintang,Jianyang,Chongzhou and other regions.(2)The value of ecological services for hydrological regulation and control of farmland system in Chengdu was the highest,exceeding 1.04 million yuan;From the perspective of land type,the total ecological service value of paddy fields is higher than that of dry land and irrigated land,especially the total ecological service value and regulation service value of paddy fields.From the perspective of spatial distribution,the value of supply and support services of farmland ecosystem in Chengdu showed the characteristics of "high in the east and low in the west",and through the superposition of various ecological service values,the total ecological service value of Renmin Qu Irrigation Area,Chongda Irrigation Area,Qiongpu Hilly Agricultural Area,Bihe Qingbaijiang Agricultural Area and Eastern Hilly Agricultural Area was higher,and the total ecological service value of Dujiangyan Irrigation Area and Shuangliu-Xinjin Irrigation Area was low.(3)The analysis of the ecological security pattern of farmland system in Chengdu showed that there were differences in the type and level of non-tillage habitat landscapes of farmland ecosystems in different districts and counties of Chengdu,among which the non-tillage habitats of farmland ecosystems in Chongzhou,Dayi,Dujiangyan,Pengzhou,Qionglai,Wenjiang and other districts and counties were less disturbed by human beings.The number of non-tillage habitat landscape patches in the farmland ecosystems of Jintang,Jianyang and Shuangliu districts and counties was large,and the landscape shape was relatively complex.The distribution of non-tillage habitats in farmland ecosystems in Chenghua,Jinniu,Jinjiang,Shuangliu,Wuhou and Xindu counties was relatively balanced.Xindu,Jinniu and Qingyang have the highest comprehensive landscape index of farmland ecosystems.The western Wenpidu irrigation area and Shuangliu-Xinjin irrigation area of Chengdu farmland ecosystem have low ecological resistance and high ecological corridor density,which is conducive to the exchange and storage of species within the farmland ecosystem,improves the communication rate and frequency of species and genes,and enhances the anti-interference ability and stability of farmland ecosystem.The ecological resistance of Jintang County and the vicinity of Longquan Mountain in the eastern hilly area is high,the density of ecological corridors is low,the population resistance ability is weak,and the biodiversity supply capacity is weak,resulting in the imbalance between supply and demand of biodiversity supply functions in farmland ecosystems.(4)Based on the analysis of the characteristics of ecological functions,ecological services and ecological security patterns of Chengdu’s farmland system,it is suggested that Chengdu’s farmland system should strengthen the protection of cultivated land and prevent the "non-grainization" of cultivated land by establishing and improving evaluation systems,establishing supervision technology systems,and adhering to the priority of cultivated land planting and utilization in areas where there is an imbalance between supply and demand in primary productivity and carbon sequestration capacity.Second,the construction of ecological corridors in the east should be strengthened,the construction of ecological ditches should be strengthened,and the material circulation,energy flow and information exchange of various elements within the farmland system of Chengdu should be promoted.Third,in the areas where the ecological services of the farmland system in Chengdu urgently need to be improved,strengthen the construction of farmland infrastructure and cultivated land capacity,strengthen the quality improvement and transformation of high-standard farmland,pay attention to protecting the habitat of organisms in the agricultural production system,and avoid destroying the habitat of farmland organisms. |
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