| The rice-crayfish co-cultivation model is a kind of cultivation of Procambarus clarkii while planting rice in the paddy field.It is an efficient ecological agricultural planting model that organically combines the aquaculture industry with the agricultural planting industry.At present,the rice-crayfish co-cultivation model in my country is mainly distributed in the middle and lower reaches of the Yangtze River,including Hubei,Hunan,Jiangxi,Zhejiang,Anhui,and Jiangsu,with Qianjiang City in Hubei Province as a model.The rice-crayfish co-cultivation model makes full use of the light,heat,water and biological resources of the rice field environment to grow rice and crayfish s,which can not only increase the utilization rate of farmland resources,but also obtain higher economic benefits,but also increase biodiversity and soil Fertility and promote the stability of the rice field ecological environment system.In recent years,with the maturity of rice-crayfish co-cultivation technology and the continuous promotion of rice-crayfish co-cropping technology,as well as the high-efficiency income brought by rice-crayfish co-cropping,the rice-crayfish co-cropping area has been expanding and the area has been growing,and its spatial distribution It is complicated,which has attracted a large number of scholars’ in-depth research.Related research mainly focuses on rice-crayfish co-cultivation technology,rice-crayfish co-cropping risk management,impact of rice-crayfish co-cropping on soil environment,and sustainable development of rice-crayfish co-cropping.Few scholars have set foot in using agricultural remote sensing technology to identify rice-crayfish co-cultivation areas and their impact on the ecological environment.Agricultural remote sensing technology can not only identify the area and spatial distribution information of rice-crayfish co-cultivation efficiently,quickly,accurately,and on a large scale,but also measure and monitor the ecological environment.The use of agricultural remote sensing technology to identify rice-crayfish co-cultivation areas can expand the capabilities of agricultural remote sensing.In the research field,improve the research on the recognition,extraction and classification of crop spatial information.Exploring the temporal and spatial evolution of rice and crayfish co-cultivation areas is of great significance for ensuring the safe production of rice and crayfish co-cultivation,the social supply of rice and crayfish,and government departments formulating corresponding management and planning policies for rice and crayfish cultivation.Analyzing the impact of the temporal and spatial evolution of rice and crayfish fields on the ecological environment is an important measure to prevent the decline of soil fertility,reduce environmental pollution,and maintain ecological balance in the rice and crayfish co-cultivation areas.In this study,Qianjiang City,a national model of rice and crayfish co-cultivation,was used as the research area.With the help of the Google Earth Engine cloud platform,Landsat-8 and Sentinel-2 remote sensing images were used as data sources to construct time-series remote sensing image data for the whole year of 2015～2020.Obtained the inter-annual spectral change law of the crayfish rice field,the original spectral characteristics and the spectral index were combined,and the rice and crayfish field extraction method based on the seasonal difference of the water body was used to identify the spatial distribution area of the annual rice and crayfish field in Qianjiang City,reveal its temporal and spatial evolution,and extract the remote sensing ecology The index reflects its image of the ecological environment,and the following conclusions are obtained:(1)Based on the Google Earth Engine data processing platform,construct Sentinel-2 and Landsat-8 time series remote sensing image data,extract the seasonal spectral characteristics and water index of the rice and crayfish fields,and extract the rice and crayfish fields by using the rice and crayfish co-cropping extraction method based on seasonal differences in water,The overall extraction accuracy is between 86.56%～90.21%,and the Kappa coefficient is between 0.71～0.89,achieving the expected extraction effect;using remote sensing images to extract the vegetation index(NDVI),soil structure-bare soil index(NDBSI),humidity Index(WET)and land surface temperature(LST),using principal component analysis to determine the weight of each index,and establishing a remote sensing ecological index model.The calculation model shows that the ecological environment of Qianjiang City is "excellent,good,fair,poor,and poor".Levels.(2)The characteristics of the spatial and temporal evolution of rice and crayfish fields in Qianjiang City from 2015 to 2020 are:the overall spatial distribution pattern is "dense in the west and southwest,sparse in the east and northeast",and the distribution is gradually decreasing from southwest to northeast.The density takes the township as the core and the rural sporadic distribution pattern.In 2015,the rice and crayfish fields in Qianjiang City were mainly distributed in the southern,central and western regions;in 2016,the rice and crayfish fields in Qianjiang City were mainly distributed in the southwest;in 2017,the rice and crayfish fields in Qianjiang City were mainly distributed in the western and southern regions;2018 The rice and crayfish fields in Qianjiang City are concentrated in the western region in the year;in 2019 and 2020,the spatial distribution of rice and crayfish fields in Qianjiang City is larger in the western region than in the eastern region,and the southern region is larger than that in the northern region.(3)Characteristics of spatial changes in rice and crayfish fields in Qianjiang City from 2015 to 2020:In 2016,the spatial number of rice and crayfish fields in Qianjiang City changed significantly in the southwest;in 2017,the spatial amount of rice and crayfish fields in Qianjiang City changed in the southwest and southern regions.The changes are obvious;in 2018,the spatial number of rice and crayfish fields in Qianjiang City changed in the western region and showed a large-scale,concentrated and contiguous distribution;the spatial number of rice and crayfish fields from 2019 to 2020 did not change significantly,mainly showing sporadic and scattered changes.(4)The characteristics of the quantity change of rice and crayfish field area in Qianjiang City from 2015 to 2020:The spatial distribution area of rice and crayfish field in Qianjiang City from 2015 to 2020 is 6870.33hm2,16040.35hm2,17437.74hm2,31496.09hm2,35565.07hm2,and 38138.08hm2,respectively,with a growth rate They were 133.43%,8.71%,80.62%,12.92%,14.83%.Among them,2016 was the starting point for the increase in the area of rice and crayfish fields,and the growth rate showed a fluctuating downward trend and gradually stabilized.(5)The spatial evolution trend of rice and crayfish fields in Qianjiang City from 2015 to 2020:The elliptical distribution direction of the standard deviation of rice and crayfish fields from 2015 to 2020 is southeast-northwest,showing a "one" shape change,and the area is increasing in the east-west direction.The overall distribution direction is from southeast to northwest.It can be concluded that the spatial distribution of rice and crayfish fields in Qianjiang City has a tendency to evolve to the northwest and northern regions.(6)The characteristics of the spatial and temporal distribution of Qianjiang’s ecological environment quality from 2015 to 2020 in Qianjiang City:The overall ecological environment in the west and southwest is better than that in the east,north and northeast;areas with poor and poor ecological environment are mainly distributed in Qianjiang The northern and northeastern regions of the city;those with a general ecological environment grade are mainly located in the central region;those with a good and good ecological environment grade are mainly distributed in the western and southern regions.Changes in the ecological environment of Qianjiang City are mainly in a fluctuating optimization pattern.The ecological environment in most areas has been improved and improved,while some areas have shown a deteriorating trend.The overall ecological environment has tended to be stable and has been continuously optimized.(7)The impact of rice and crayfish fields on the ecological environment:The correlation analysis shows that the rice and crayfish fields have a significant impact on the ecological environment.The impact of rice and crayfish fields on the ecological environment in a single year is not significant.With the increase in the area of rice and crayfish fields and the expansion of the distribution area,as well as the long-term series of rice and crayfish co-cultivation,the rice and crayfish fields have the function of optimizing the ecological environment,making rice and crayfish co-cultivation areas The quality of the ecological environment has been continuously improved;long-term rice and crayfish co-cultivation has the functions of reducing environmental pollution,purifying water sources,increasing biodiversity,improving soil fertility,and maintaining ecological balance. |
PDF Full Text Request