| Rice-crayfish farming mode is a new rice field ecological comprehensive cultivation mode combining the cultivation of crayfish and rice cultivation.This mode makes full use of the three-dimensional space of the rice field,the light,heat,water and biological resources,and the cultivation of crayfish can not only obtain high economic benefits,but also maintain the soil fertility,maintain the ecological balance,and form a mutually-beneficial symbiosis complex ecological agriculture system.In recent years,the rice-crayfish farming mode has been popularized throughout the country,and the area of rice-crayfish farming Area has been constantly increasing.The research related to the rice-crayfish farming mode mainly focuses on the cultivation technology and the impact on the soil environment.Few scholars have studied the application of agricultural remote sensing technology to efficiently,quickly and accurately identify large areas of rice-crayfish field.Using remote sensing technology to invert rice-crayfish field and obtain information such as area and spatial distribution can extend the application field of agricultural remote sensing,supplement the classification research of crop remote sensing and promote the development of precision agriculture.It is of great significance to analyze the temporal and spatial evolution of rice-crayfish farming area for farmers to choose rice-crayfish farming area,for enterprises to grasp the development trend of crayfish industry,and for the government to formulate corresponding management policies.The driving force of the evolution of rice-crayfish farming area can be deeply explored,and the main factors can be summarized to provide guidance and theoretical support for the promotion of rice-crayfish farming mode.Therefore,in this paper,the Yunliang Lake management area is used as the research area,and the Sentinel-2 satellite remote sensing data is used to construct the time series remote sensing data from 2016 to 2019.The law of annual spectral changes of rice-crayfish fields is obtained.Combine the features and texture features to generate a hybrid spectral image,use the random forest classification algorithm to identify the annual rice-crayfish field distribution area in the study area,reveal its temporal and spatial evolution rules,and combine the field farmer questionnaire results and socioeconomic and location data in the research area to explore the temporal and spatial evolution of the rice-crayfish field driving factors,the following research conclusions are drawn:(1)The use of Sentinel-2 time series of remote sensing image,extraction of remote sensing spectrum 2 characteristics of vegetation index,a index of soil features,1 water index and 10 texture feature,and the 13 original spectral fusion for 27 characteristic spectrum of mixed spectrum data,using the random forest algorithm,can effectively to the rice-crayfish fields in the study area,pure rice paddies,waters,buildings,rural roads/ridge,the other six main feature type interpretation classification.The overall accuracy of the classification results ranged from 78.06%to 95.61%,and the Kappa coefficients ranged from 0.71 to 0.94.Thus,the area and spatial and temporal distribution of rice-crayfish farming area were accurately extracted.(2)The spatial and temporal evolution characteristics of rice-crayfish field in the study area from 2016 to 2019 are as follows:the area and quantity of rice-crayfish fields increase year by year,and the growth rate is the fastest in 2018,with the area increasing by 22.39%compared with the previous year.The total area of rice-crayfish fields in 2019 accounts for 64.62%of the land area of the Grain Transport Lake management area.The spatial layout has changed significantly,expanding from northeast to southwest,gradually occupying the farmland except for the agricultural technology popularization center.Affected by the form of administrative region,rice-crayfish fields were mainly distributed in the north and east.(3)The spatial and temporal evolution characteristics of the five main feature types in the study area from 2016 to 2019,except the rice-crayfish fields,are as follows:The area of pure rice field gradually decreases,accounting for 1.97%of the total area of the management area by 2019.With the increase of rice-crayfish field,the space gradually decreases from northeast to southwest and is scattered around the rice-crayfish field.The water area first increases and then decreases.By 2019,the water area will account for 2.49%of the total area of the management area,and will always occupy the park pond.A few aquaculture ponds are distributed in the southeast corner.The building area increased steadily,accounting for 13.43%of the total area of the management area by 2019.It is mainly distributed in the town center of the management area.The area of rural road/field ridge decreases year by year,accounting for 15.06%of the total area of the management area in 2019.The area of other feature types increased first and then decreased,mainly distributed along the Grain Transport river and in the southeast of the management area.(4)The driving factors for the time evolution of the rice-crayfish farming area in the research area from 2016 to 2019 are as follows:From the aspect of market demand analysis,crayfish market demand,prospect and the formation of industrial chain promote the promotion of rice-crayfish farming mode;From the aspect of economic benefit analysis,on the micro level,farmers are driven by economic benefit to engage in rice-crayfish farming.The overall economic benefit of rice-crayfish farming and crayfish breeding industry in China drives farmers to choose rice-crayfish farming from the macro level.From the aspect of national policy support,the national policy of "targeted poverty alleviation" supports the development of rice-crayfish farming industry,the implementation of local government policies and the technical promotion of rice-crayfish farming mode also promote the development of rice-crayfish farming industry.From the analysis of natural factors,topographic conditions and water quality are the indispensable factors affecting the development of rice-crayfish field From the analysis of location factors,the external traffic location factors of rice-crayfish farming area directly affect the daily field management of rice-crayfish field and the sales and transportation of crayfish,and the land use location factors within the research area also indirectly affect the development of rice-crayfish field. |
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