Study On Land Use Change And Its Influence On Land Ecological Security In Yarkant River Basin Of Xinjiang

Land use change is a prominent manifestation of human social activities.The structure and function of land ecological security are closely related to land use change.With the rapid development of society and economy,people’s utilization of land has been increasing,and the contradiction between people and land has become more and more acute,which also increases the impact on the ecological environment.Therefore,it is of practical significance for the sustainable use of regional land resources to grasp the changes of regional land use and deeply study the relationship between land use and ecological security.Taking the Yarkant River Basin as the research target area and based on remote sensing images,this paper mainly analyzes the characteristics of land use change in the Yarkant River Basin from 1982 to 2017 from different perspectives.On this basis,PSR framework model is used to analyze and comprehensively evaluate the ecological security problems caused by land use change in the Yarkant River Basin,and the obstacle degree model is used to screen out the main obstacles to land ecological security in the evaluation index system.Finally,the gray series GM(1,1)model is used to quantitatively predict the change of land ecological security in the study area in the next 10 years.The following conclusions are drawn:(1)The main types of land use in the Yarkant River Basin are unused land,cultivated land and grassland.From 1982 to 2017,the area of cultivated land and construction land increased,while the area of forest land,grassland,water area,wetland and unused land decreased,among which the area of water and wetland fluctuated less.In the past 35 years,the cultivated land area increased the most(165.46%),and the forest land area decreased the most(43.49%).The dynamic attitude analysis of land use shows that different types of land use in the research area have drastic internal transformation and complex structure.From the perspective of the change of land use degree,the land use degree remains between 125.25 and139.75,and is still in the state of development.From the perspective of land use structure change,the difference between different types of land use structure and the total land area in the Yarkant River Basin is gradually decreasing,the diversity of land use structure is increasing,the degree of order is gradually decreasing,and the land use structure is in an unstable state.From the perspective of the transfer trend of land use types,the main transformation direction among land use types is grassland,forest land and water area are into cultivated land and unused land,and unused land into cultivated land,grassland and forest land.(2)From 1982 to 2017,the level of land ecological security in the Yarkant River Basin continued to improve,with the comprehensive index of land ecological security rising from 0.2784 to 0.6072,indicating that the level of security experienced a development process of “deterioration level—risk level—sensitivity level”.During this period,the composite index increased by 0.3288.Although the land ecological security index kept increasing,the security degree was still in a sensitive state,and the importance of ecological environmental protection still needed to be further enhanced.The pressure index of land ecological security is generally on the decline,while the state and response index are on the rise.From1982 to 2017,the main obstacles to land ecological security include pesticide application per unit of cultivated land,natural population growth rate,grassland area proportion,forest area proportion,water area proportion,fertilizer application per unit of cultivated land and plastic film application per unit of cultivated land.In the long run,the pressure layer is the dominant factor affecting the ecological security of land.(3)2020-2030 Yarkant River Basin watershed land ecological security level is obviously growth trend,its security level by level "sensitive" into "security level",security levels will also be changed from “Ⅲ” to “Ⅴ”,but the land ecological safety pressure index is on the decline,pesticide application per unit of cultivated land,the natural population growth rate,grassland area proportion,forest area proportion,water area proportion,fertilizer application per unit of cultivated land and plastic film application per unit of cultivated land index will remain,such as the key to improve the level of land ecological safety factor.