Analysis On Land Use Change And Landscape Ecological Risk In Gansu Section Of The Mainstream Of The Yellow River

Land is the basis of human activities and social development.Human activities have caused the change of land use.Meanwhile,the change of land use has a subtle impact on human life and ecological environment.In recent years,urbanization and socioeconomic development in Gansu section of the Yellow River main flow have caused land use changes,which have threatened ecological security to a certain extent.To ensure the integrity and stability of the ecosystem and its healthy development is the basis and guarantee of human survival and development.Therefore,it is particularly important to explore the changes of land use caused by human activities and the risks faced by ecological security to improve the ecological environment in Gansu section of the Yellow River main stream.Based on the above background,in this paper,based on ARCGIS and FRAGSTATS,a quantitative analysis of land use data evolution attitude analysis,land use transfer matrix and landscape pattern calculation in Gansu section of the Yellow River main stream from1990 to 2020 was carried out to reveal the spatio-temporal change characteristics of land use in the study area,and a landscape ecological risk assessment model was built based on landscape index.ARCGIS was used for spatial visualization of ecological risk values to explore the spatial distribution characteristics of ecological risks in the study area.Geo Da was used for spatial correlation analysis of ecological risk areas.Finally,GM(1,1)grey model was built by MATLAB to predict the status of land use change in 2030 and the distribution characteristics of ecological risks.The main research conclusions are as follows:(1)The area change of land use types in Gansu section of the Yellow River main stream showed a trend of decreasing grassland,cultivated land,unused land and forest land,while increasing construction land and water area.The change of cultivated land area in Gannan showed an increasing trend,the unused land area in Linxia showed an increasing trend,and the water area showed a decreasing trend,the unused land in Lanzhou showed an increasing trend,and the unused land and forest land in Baiyin showed an increasing trend.In addition,the other change trends of each city and state were consistent with the overall change trend.The transfer area of land use type was 2008.45km~2,398.76km~2,1562.22km~2,2279.95km~2,respectively,and the rate of change was from high to low in Lanzhou,Baiyin,Gannan and Linxia.With the evolution of time,the landscape fragmentation in the study area increased,the shape area became complicated,the connectivity became poor,the stability decreased,the landscape diversity in the region increased,the dominance degree decreased,and the distribution of land use types became uniform.(2)From 1990 to 2020,the overall ecological risk in Gansu section of the Yellow River main stream showed a rising trend,in which the areas of high ecological risk,high ecological risk and medium ecological risk showed a shrinking trend,while the areas of low ecological risk and low ecological risk continued to expand.In a certain region,the increase of the proportion of unused land,water area and construction land will lead to the improvement of ecological risk,and the increase of the proportion of cultivated land will also lead to the improvement of landscape ecological risk,but the impact is lower than that of unused land,water area and construction land.Grassland and woodland are the main land use types to reduce landscape ecological risk.(3)Without external interference,the land use type structure of Gansu section of the Yellow River main stream will not change in 2030.Grassland,cultivated land and forest land are still large land use types,and they account for more than 90%of the total land use area in the study area.However,compared with 2020,In the study area,the area of grassland and cultivated land decreased,while the proportion of woodland area increased.Compared with the above three land types,the land area of the other three land types was relatively small,and the proportion of unused land,construction land and water area increased.There were differences in the area changes among cities and states.(4)Without external interference,the overall ecological risk of Gansu section of the Yellow River main stream will be further improved in 2030.The overall ecological risk level of the study area increased from 0.0135 to 0.141.The low ecological risk area,middle ecological risk area and high ecological risk area showed an expanding trend,while the low ecological risk area and high ecological risk area showed a shrinking trend.The ecological risk level of Gannan and Baiyin showed a downward trend,while Linxia and Lanzhou showed an upward trend.From the grid evaluation units,from 2020 to 2030,the grid with rising ecological risk occupies a small proportion and mainly distributes in the area with more cultivated land and construction land,while the grid with declining ecological risk occupies a large proportion and mainly distributes in the area with more grassland and forest land.