| The Weigan-Kuqa River Basin is an important tributary of the Tarim River Basin.Due to the impact on human activities and natural factors,the land use of the basin changed significantly,and the pressure on water and land resources continued to increase,which seriously threatens the ecological environment security and social development in the river basin.This paper mainly studies the spatial-temporal pattern of land use and net primary productivity of vegetation in the Weigan-Kuqa River Basin,and focuses on the relationship between land use change and net primary productivity of vegetation in the watershed.Clarified the main factors affecting the land use change in the basin and the impact on land use change of the net primary productivity of vegetation.The main conclusions are as follows:(1)From 1990 to 2017,the land-use changed trend in the Weigan-Kuqa River Basin mainly showed the increase in the area of cultivated land and unused land,as well as the sharp decrease in the area of grassland.Among them,the area of cultivated land expanded by 66.17%.The area of unused land increased by 2190.08 km2,and the rate of rise was 81.11 km2/a.The area of grassland degraded to varying degrees,with a decline rate of 132.08 km2/a.and the overall decline was 24.69%.Both the information entropy and the equilibrium degree increased,indicating that the degree of systematization of regional land use disorder increased,and that the land use structure became more balanced.The conversion to grassland and unused land to cultivated land in the basin was concentrated in the middle reaches of the Weigan River and the lower reaches of the Kuqa River.(2)The main driving factors of land use change in the Weigan-Kuqa River Basin were natural factors and socioeconomic factors.The temperature and precipitation in the study area increased significantly,which accelerated the melting speed of mountain glaciers,resulting in an increase in the water area of the basin.Ecological problems such as frequent natural disasters and increased soil salinization.During this period,the population center of gravity shifted from the southwest to the northeast,and GDP was opposite to the direction of population migration,indicating that the spatial distribution of population and economy was uneven.Due to the rapid development of society,human beings' efforts to develop natural resources continued to increase,leading to the rapid expansion of cultivated land and the drastic reduction of grasslands,resulting in a decrease in biodiversity,thereby deepening the contradiction between human and land relations.(3)From 2000 to 2017,the overall change range of vegetation NPP in the river basin was between 144.97-101.70 g C·m-2·a-1,the overall decrease of vegetation NPP was as high as 29.85%.The annual average total NPP of the five counties in the river basin was ranked as Baicheng County>Kuqa County>Xinhe County>Wensu County>Shaya County.The NPP of grassland,woodland and construction land was in a downward trend,and the decline in grassland was as high as 42.97%,while the NPP of cultivated land increased significantly,an increase of 18.58%.The contribution rate of cultivated land change of vegetation NPP in the watershed was as high as 66.32%,followed by grassland was 31.15%.Land use change had a significant impact on vegetation NPP in the Weigan-Kuqa River Basin. |
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