Comprehensive Evaluation Of Agroecological Index In Hainan Island And Remote Sensing Monitoring Of Key Indicators

Hainan Island as China’s largest tropical island,has the unique conditions for the development of tropical agriculture.Hainan Island arable land planting system is mostly multi-year system,but arable land abandonment phenomenon is more common;Hainan Island abundant precipitation,but there are also uneven seasonal distribution,seasonal drought and even agricultural disasters frequently.Therefore,there is an urgent need to carry out the research of agroecological monitoring and comprehensive assessment methods in Hainan Island.In this paper,using remote sensing technology and GIS spatial analysis method,on the basis of comprehensive consideration of Hainan Island’s agroecological monitoring needs and regional characteristics,the remote sensingbased Hainan Island agroecological monitoring index system and assessment methods are constructed,and the agroecological conditions of Hainan Island in different periods are evaluated and analyzed.The main research results and conclusions are as follows.(1)For the problem of monitoring the cultivated land replant index of Hainan Island,the long time series Sentinel-2 satellite image data and Savitzky-Golay filter method were used to monitor the multiple cropping index of Hainan Island.The results show that the overall accuracy of the multiple cropping index extraction method of Hainan Island reaches 91.94%,and the Kappa coefficient is 0.88.The multiple cropping index of Hainan Island is improved from 1.53 in 2016 to 1.66 in 2020,and the multiple cropping index in each city and county of Hainan Island ranges from 1.28 to 1.96.(2)For the problem of remote sensing monitoring and comprehensive assessment of agroecology on Hainan Island,eight indicators,including multiple cropping index,vegetation growth index,vegetation health index,surface temperature,precipitation,Fraction of photosynthetically Active Radiation(FPAR),topography index,and crop disaster index,were selected,and a comprehensive assessment model of agroecology on Hainan Island was constructed by combining Delphi and hierarchical analysis with the assignment method.The results show that the island-wide agroecological index of Hainan Island in 2020 ranges from 0.34-0.97,with a mean value of 0.73;the change of agroecological index of each city and county in Hainan Island in 2020 ranges from 0.68-0.78.(3)For the issue of the driving factors affecting the spatial and temporal changes of the agroecological index of Hainan Island,the driving factors of the spatial and temporal changes of the agroecological index of Hainan Island were analyzed by using the geographically weighted regression method.The results show that surface temperature has the greatest influence,followed by vegetation growth index,FPAR,precipitation,cropland replanting index,topography index and other indices.In addition,surface temperature and multiple cropping index showed negative correlations,while all other factors showed positive correlations.