| Farmland is the material basis of human survival.However,with the social and economic development of China,rapid industrialization and urbanization have threatened the quantity and quality of farmland.Moreover,with people's transition from food demand to spiritual demand,farmland has gradually evolved from a single production function to a synthesis of multi-function,including production,ecology,aesthetics and recreation etc.Therefore,in the context of rural revitalization and ecological civilization construction in China,it is urgent to fully grasp the current situation of farmland,comprehensively and deeply analyze its multi-function,and propose a scientific,effective and sustainable method of farmland protection.This paper takes Hangzhou City,a typical economic city with weak resources,in the southeast coast of China,as the study area.With the help of remote sensing and geographic information systems,we fully exploited the multi-source agricultural big data to analyze the spatiotemporal patterns of the production function,ecological function and landscape cultural function of farmland in Hangzhou during 2010-2014.Among them,this paper focused on evaluating the landscape cultural function of farmland with relatively high challenges.Then,we further explored the comprehensive information of multi-function of farmland,including the matching analysis between supply and demand,correlation analysis between synergy and trade-off.On the basis of comprehensive analysis,the demarcation plan of the farmland was formed and the spatial division of the farmland in Hangzhou was realized.Finally,we established the multi-functional collaborative optimization strategy and protection measures of the farmland in each sub-area under different development targets.The main research contents and conclusions are as follows:(1)Grasping the existing problems and proposing the necessity of differentiated management by analyzing the spatiotemporal characteristics of farmland.The results showed that,from the perspective of occupation and supplementation,the farmland in Hangzhou generally showed the spatial patterns of occupying paddy fields and supplementing dry land,as well as occupying the surrounding urban areas and supplementing areas far from the city.From the perspective of morphology,the farmland near the city was fragmented,with the core category decreasing and the islands increasing.In the remote areas,due to the supplementation of farmland,the core category increased.However,the marginal and perforated categories also increased year-on-year,and the shape regularity of farmland declined.It can be seen that the farmland with high quality in Hangzhou has been eroded due to the overlap with the economically developed areas.The process of farmland occupation and supplementation needs more scientific guidance and reference,and the differentiated management of farmland needs further improvement.(2)Analyzing the individual functions of farmland and understanding the basic information of these functions.a)Production function of farmlandThis study integrated the natural and social factors to construct a comprehensive evaluation index system for evaluating the production potential of farmland.Then,the distribution pattern of the comprehensive production potential of farmland in Hangzhou was obtained by amending the climate production potential.The results showed that the comprehensive production potential of farmland was mostly at the second level(44.68%),35.83% farmland with production potential at the first level,and farmland with production potential at the third level accounted for 19.49%.In terms of spatial distribution,the farmland with high production potential was mainly concentrated in Yuhang District,Fuyang District,Xiaoshan District and Tonglu County.These farmlands have the fertile soil,gentle terrain,rich water source,convenient transportation and regular plot with high connectivity.The farmland with low production potential was mainly interspersed in the hilly areas of the northwest and southern regions.These farmlands have relatively poorer soil fertility,lower connectivity,general infrastructure conditions,irregular shape of the plot and higher elevation.The overall production potential of farmland in Hangzhou City during 2010-2014 had not changed much,and the regional variation was mainly caused by the change of farmland area.b)Ecological function of farmlandAccording to the concept of ecosystem services,and considering the representativeness of function,the availability of data,as well as the scientificity of assessment methods,this study selected four sub-functions,including soil conservation,habitat maintenance,landscape connectivity and environmental health,to comprehensively characterize the spatiotemporal patterns of ecological function of farmland in Hangzhou.The results showed that the integrated ecological function of farmland in Hangzhou was weak,and the differences between regions were significant.Among them,the farmland with ecological function at the first level and the second level accounted for 7.82%,and 12.54% of farmland in Hangzhou,respectively.They were mainly distributed in the mountainous hilly areas such as Lin'an District,Jiande City and Tonglu County.These farmland were generally far away from the city and surrounded by forests.They had fewer human interference factors and the ecosystem tends to be stable,thereby the ecological function of these farmland was relatively strong.The farmland with ecological function at the lowest level accounted for 79.64%,and mainly distributed in the plain area of the northeastern part of Hangzhou,like Yuhang District and Xiaoshan District,etc.These regions had dense population and high-intensity construction,thereby the farmland within these areas had lower habitat quality and more general landscape conditions.In terms of temporal dynamics,the ecological function of farmland in Hangzhou decreased slightly during 2010-2014.The ecological protection task of farmland is still arduous.c)Landscape cultural function of farmland.This study explored the spatiotemporal patterns of the supply,demand and flow of landscape cultural function in farmland by integrating agricultural big data and the maximum entropy model and viewshed analysis etc.We observed that recreational farmland was highly dependent on human factors and primarily concentrated near the city center.In contrast,aesthetic farmland was closely related to natural attributes and mainly distributed in rural areas.The results also showed the more rapid growth of recreational supply than the aesthetic supply for farmland in Hangzhou.In terms of the demand and flow level,we found that high-demand farmland were mainly concentrated near the downtown area,and the flow patterns were greatly affected by surrounding famous scenic spots.Finally,strategies for sustainable utilization of farmland could be formulated based on guaranteeing the rational use of farmland in densely populated areas,creating more suitable farmland in potential areas,and raising awareness and public infrastructure for farmland with lower utilization.(3)Comprehensively evaluating the multi-function of farmland around the matching analysis between supply and demand,the correlation analysis between synergy and trade-off.Firstly,we used the resident population,rural tourism population,GDP and green space ratio index to represent the demand level of farmland functions.Then,the bivariate local Moran's I index was used to analyze the matching condition between supply and demand.In terms of the matching condition between supply and demand,it was relatively misplaced about the ecological function,and relatively high about the landscape recreational function,and the supply and demand area was flat for the production function of farmland.On the basis of matching analysis,we divided the farmland into four groups of C1,C2,C3 and C4 by the k-means clustering algorithm.Furthermore,this study also explored the synergy and trade-off relationships between the functions of farmland.Firstly,qualitative analysis was carried out by the spearman correlation analysis.The results showed that there was a strong synergistic relationship between production function and landscape recreational function.While the relationships between ecological function and the other functions were mainly trade-off.Then,through the calculation of coupling coordination degree,the spatial quantitative analysis was carried out.We found that the flat areas in the northern and central Hangzhou had higher coordinating degree between multi-functions,and farmlands with higher trade-off degree between multi-functions were mainly distributed in the western and southern mountains.(4)Zoning farmland based on the results of comprehensive multi-functional evaluation and proposing suggestions for differential optimization management.Firstly,the four groups obtained by the above clustering analysis were used as the basic zones.Then,the basic zones were superimposed with the multi-functional coupling degree of farmland to further obtain six functional zones of the farmland in Hangzhou as follows:a)Urban agricultural recreational region(accounting for 8.32%).These farmlands were mainly located around the city and had generally high demand level for various functions by the residents.It was recommended that the farmland be multi-functionalized and coordinated as the future development direction.b)Green agricultural sightseeing region(accounting for 10.23%).These farmlands were mainly distributed in the plain areas located in the suburbs of the city,like the Yuhang District,Xiaoshan District and Fuyang District etc.Production function was the dominant function of these farmlands.We encouraged convert these farmlands to green pastoral complex that was suitable for production,tourism,and ecological maintenance.c)High-efficient agricultural demonstrative region(accounting for 26.26%).These farmlands were mainly distributed in the suburbs of Hangzhou,such as the Xiaoshan District,Yuhang District and Fuyang District etc.Due to intensive agricultural production activities and excessive application of fertilizer and pesticide,the multi-functional coupling coordination degree of these farmland was general.We recommended to strengthen the environmental pollution control and supervision,and develop scientific,technological,ecological and labor-intensive agriculture.d)Aesthetic agricultural production region(accounting for 9.98%).These farmlands had relatively high-quality and located in rural areas,including the farmlands in valley plain and the terraces in mountainous areas.It was recommended to rely on its unique rural landscape and its surrounding scenic spots that were closely related to historical ancient villages and farming culture to promote the coordinated development of farmland.e)Special agricultural developing region(accounting for 21.56%).These farmlands were mainly distributed around the aesthetic agricultural production region with relatively fragmented landscape and lower coordination.It was suggested to improve the contiguous of farmland through land remediation,and strengthen the promotion of special agricultural products to create a rural agricultural brand.f)Ecological agricultural reserve region(accounting for 23.65%).These farmlands were mainly distributed in low hilly areas such as Lin'an District,Jiande City and Chun'an County.It was recommended that the isolated islands surrounded by forests should be appropriately returned to forests and grasslands,and improve the utilization level of farmland close to the other functional regions through land remediation and use them as the ecological farmland reserve. |
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