Land Use Change And Ecological Security Evaluation In Chaohu Basin

Land use change is the most intuitive manifestation of land surface changes under the influence of various factors.When land is used rationally,land ecosystem is in a safe state.When the land is destroyed,the land ecosystem is out of balance,which directly threatens the present and future of human beings.Compared with other ecosystems,watershed has always been an important place for human production activities due to its excellent natural conditions.With the increase of human activities,the land use and landscape pattern of watershed have changed significantly,and the land ecological security has been significantly affected.Therefore,the protection and utilization of land resources in the basin need to be solved urgently.This thesis takes Chaohu Basin as the research object,and uses RS and GIS to obtain the land use data of Chaohu Basin in 2000,2005,2010,2015 and 2020.On this basis,it grasps the spatial-temporal characteristics of land use changes from the perspective of land use structure,dynamic attitude and landscape pattern changes.PSR model was selected to determine 21 indicators to reflect the change of land ecological security.AHP and entropy weight method were used to determine the weight of each index.The comprehensive index of land ecological security was calculated by the comprehensive index method.The main research results are as follows:(1)The land use structure and dynamic attitude changed obviously.The area of cultivated land and grassland decreased as a whole,while the area of woodland,construction land,water area and unused land increased as a whole.The area of cultivated land and construction land changed most significantly.There were mainly 16 types of land use transfer in the study area.The single dynamic attitude of cultivated land and grassland decreased the fastest,the single dynamic attitude of construction land increased the fastest,the unused land and the single dynamic attitude of woodland and water area increased continuously with a small increase range,and the overall dynamic attitude of comprehensive land use showed a trend of first rising and then declining.(2)At the patch type scale of land use landscape pattern,the landscape dominance of cultivated land and grassland decreased,the landscape dominance of construction land increased,and the landscape dominance of woodland and water area had little fluctuation,and the landscape dominance of unused land was always the lowest.The landscape fragmentation of grassland,cultivated land,woodland and unused land increased significantly.On the landscape scale,landscape diversity and evenness are on the rise as a whole,landscape shape characteristics and spread degree become more complex,landscape patch shape becomes zigzag and staggered,and the degree of aggregation and extension decreases.(3)The overall land ecological security in Chaohu Basin has experienced three processes of ascending,descending and ascending,and the security level has changed from less security to more security.The overall land ecological security index of the pressure system showed a downward trend,and the security level changed from safe to more safe and finally to less safe.The land ecological security of state system can be divided into three stages: ascending,descending and ascending,and the security level changes from less security to more security.The overall land ecological security of the response system showed an upward trend,and the security level changed from unsafe to critical and finally to safe.(4)From the three subsystems of land ecological security pressure,state and response,the pressure system obstacle degree showed an upward trend,state system obstacle degree first decreased and then increased,and response system obstacle degree showed a downward trend.From the point of view of the obstacle degree of the main obstacle factors in the index layer,there are great differences in the main obstacle factors affecting Chaohu Basin in the past 20 years.In the first ten years,environmental factors are the main obstacle factors.In the last decade,land factor and landscape factor were the main obstacle factors.(5)Through the research on the changes of land use and ecological security in Chaohu Basin,in order to further improve the level of land ecological security,combined with the development plan of the basin,the countermeasures and suggestions were put forward,such as strict control of construction land,strict protection of cultivated land,strengthening environmental protection,constructing landscape ecological security pattern,and coordinating the relationship between economic development and ecological protection.