Land Use/Cover Change And Its Eco-Environmental Effects In Kaxgar River Basin,Xinjiang

Land use/cover change is a core and hot issue of the current research on global change,and the eco-environmental effects involved in this process is considered a content that can not be ignored.With the rapid development of society and economy,the large-scale development of water and soil resources has changed the spatial and temporal pattern of oasis land types,and accordingly negatively affected the ecological environment.The Kaxgar River Basin in Xinjiang is located in the arid area of northwest China.The rapid development of society has led to the continuous expansion of arable land and the increasing scarcity of water resources.Consequently,the ecological environment of the Kaxgar River Basin has become progressively fragile.In this work,the Kaxgar River Basin in Xinjiang is selected as the research target.Subsequently,we include Landsat TM remote sensing images during the same period in 1990,2000,2010 and 2020 as the data source,and conducted in-depth discussions on the evolution of the temporal and spatial pattern of land use change in the region in the past 30 years and its eco-environmental effects through various methods,which will provide a meaningful reference for the rational development and utilization of water and soil resources in typical watersheds in arid regions and the management and protection of the ecological environment.The main conclusions are as follows:(1)During the period from 1990 to 2020,the land use structure of the Kaxgar River Basin changed significantly.Among them,the area of cultivated land expanded by 66.17%to the east,and the area of high coverage grassland and unused land increased by 1963.06 km~2and 2278.70 km~2respectively.In addition,the reduction of water area was the most significant.The area of low coverage grassland transferred frequently to cultivated land,and this change was most obvious in the eastern part of the study area.In the past 30 years,the transfer area of high coverage grassland was more than that of transfer area,which was largely transformed from medium coverage grassland.The information entropy and equilibrium degree increased at first and then decreased from 1990 to 2020,indicating that the land use system in the basin tended to be stable,but the equilibrium was weakening.,(2)The total net primary productivity of vegetation in Kaxgar River Basin showed an increasing trend from 2000 to 2020.The net primary productivity of vegetation in the watershed presented a spatial distribution pattern of high in oasis and low in mountainous and desert areas.During the study period,the net primary productivity of vegetation of all land use types in Kaxgar River basin changed significantly,of which,the cultivated land,forest land and high coverage grassland increased,while medium and low coverage grassland decreased.From 2000 to 2020,the center of gravity of vegetation net primary productivity of cultivated land,forest land and high coverage grassland was similar to that of land use type.The impact of land use change on the contribution rate of total net primary productivity reached 48.94%during 2010-2020.(3)The value of ecosystem services in Kaxgar River Basin increased at first and then decreased,among which the loss of regulatory service value was more obvious,and the change was basically affected by changes in grassland and water areas.Moreover,the service function of food production tended to increase due to the expansion of cultivated land.After 2000,the development of GDP and ecosystem service value in the watershed was negatively correlated,the degree of ecological economic coordination decreased year by year,and the ecological environment quality index decreased by-0.027 during the study period.The ecological environment of the basin showed a trend of improvement from 2000 to 2010,but after 2010,the stability of the ecological environment gradually decreased with the rapid expansion of cultivated land and the sharp decline of water area.It can be concluded that the land use/cover of Kaxgar River Basin changed significantly from 1990 to2020,causing changes in the ecological environment.Under the background of climate warming,the melting of ice and snow in mountainous areas provided sufficient water resources for the study area,so the vegetation NPP showed an increasing trend.However,due to the overexploitation of land resources,the area of water and grassland were gradually decreasing,and the indicators of eco-environmental effects were declining by degrees.Therefore,while developing society and economy and changing land use/cover,we should pay attention to the balance and stability of land-use structure to prevent from the negative effects of land use/cover changes on the ecological environment.