Study On Landscape Pattern Evolution And Future Scenario Simulation Of Poyang Lake Area

Taking Poyang Lake as an example,this paper interpreted remote sensing images in 2000,2006,2012 and 2018,and extracted five landscape types: water area,forest and grass land,cultivated land,construction land and unused land.The landscape pattern changes of Poyang lake area from 2000 to 2018 were analyzed from two aspects: patch type level and landscape level.According to the development characteristics of Poyang lake,nine driving factors of landscape pattern change are selected from the aspects of nature and social economy.Markov model was used to calculate the land demand of Poyang lake area.Dyna-clue model was used to simulate the change of landscape pattern of Poyang lake area from 2012 to 2018,and the spatial distribution of landscape pattern of Poyang lake area in 2024 was predicted under four different scenarios: natural growth scenario,farmland protection scenario,ecological protection scenario and comprehensive protection scenario.The main conclusions are as follows:(1)The landscape dynamic change of Poyang lake area was analyzed with the combination of landscape index.In the research period,forest and grassland occupied a dominant position in Poyang lake area,with the largest patch type ratio,large area fluctuation and irregular shape.The construction land area is increasing;The water area,unused land and cultivated land area showed a decreasing trend and the degree of fragmentation increased.The decrease of cultivated land area and unused land area is mainly affected by the expansion of construction land area.(2)According to the driving factor selection principle and the actual situation of Poyang lake area,9 driving factors were selected.Logistic regression model was used to quantitatively analyze the distribution probability of landscape types.Grid resolution is very important in the simulation of landscape pattern.According to the ROC value comparison of five groups of different resolutions,the resolution of 30 meters is the best resolution for the simulation of landscape pattern change in poyang lake region.The ROC value of the five landscape types was the largest under the resolution of 30 meters,and the ROC value of the five landscape types was all greater than 0.7,indicating that the influence factor could well explain the simulation of the landscape pattern of Poyang lake region under this resolution.(3)The landscape pattern change of Poyang lake in 2018 was simulated based on Dyna-CLUE model,and Kappa value was simulated Up to 0.90,indicating that the model and related parameter setting are applicable to the simulation of landscape pattern change in Poyang lake area.The simulation results can well explain the spatial change of landscape pattern in Poyang lake area.(4)The landscape pattern changes in Poyang lake region under four different scenarios:natural growth,farmland protection,ecological protection and comprehensive protection.Under the natural growth scenario,the urban and rural construction land in each urban area of Poyang lake area increased,with different increases.The growth of construction land is mainly along the existing construction land center or along the Ganjiang river.Part of the area is filled along the city interior.The area of cultivated land decreased in Nanchang county,Xinjian county,Yongxiu county and Nanchang urban areas.Other landscape types decreased mainly in Nanchang county and Xinjian county.Under the protection of cultivated land,the cultivated land area occupied by the construction land in new areas is reduced,mainly converted from the unused land such as tidal flat.Farmland in various counties and districts has been protected.The increase of construction land decreased and the expansion direction was orderly,but it occupied part of the area of forest and grass land,resulting in the destruction of forest and grass land and other ecological land.In the context of ecological protection,the overall growth rate of forest and grassland is accelerated.The urban area of Nanchang,Jinxian county,Poyang lake and other waters are well protected.The expansion direction of construction land is orderly,but it occupies part of high-quality farmland.Compared with the previous three scenarios,the comprehensive protection scenario not only gives consideration to the development of social economy,but also considers the protection of ecological environment and cultivated land in the research area,which is conducive to the sustainable development of Poyang lake area.(5)Through the simulation of landscape pattern change in Poyang lake area,it can be seen that the landscape pattern change in Poyang lake area has some problems,such as unreasonable structure and unreasonable layout,etc.In the future,the increment and expansion direction of construction land should be controlled in the process of landscape pattern change in Poyang lake area,so as to protect high quality farmland,maintain wetland and protected land.