Analysis Of Spatial-temporal Changes Of Desert Vegetation And Causes In Wucaiwan Open-pit Mining Area

In the northwest of China,there is a vast desert area with poor ecological environment.With the vigorous development of natural resources such as coal in the west,the originally fragile ecological environment has been challenged like never before.Vegetation has the function of "indicator" when studying ecological environment changes,and the degree of change can reflect the ecological environment in a region.In order to study the impact of the vigorous development of coal resources on the ecological environment in the desert area,the vegetation NDVI was selected as the indicator of the ecological environment in the desert area.This article takes the Wucaiwan large open-pit coal mine located in the Zhundong desert area as a research object,integrates RS,GIS and other technical means,through long-term monitoring from 1990 to 2017,and combines precipitation,temperature,nitrogen deposition,and mining area development.Human factors,research on the temporal and spatial changes of vegetation in and around the mining area,and achieved the following results:On the time scale,the Landsat-NDVI sequence of nearly 30 years was used to realize the annual and monthly monitoring and analysis of the desert vegetation in the mining area and surrounding areas.The results show that the desert vegetation in the study area has obvious phenological characteristics of short-lived vegetation,and the vegetation has a tendency of "increasing first and then decreasing" with mineral development.Through correlation analysis of desert vegetation and meteorological factors in this area,it is found that vegetation NDVI has obvious correlation with climatic factors,and the response of vegetation to precipitation changes is more sensitive.At the same time,due to the ecological protection measures carried out in the mining area in recent years,the vegetation has improved significantly under the combined effects of increased precipitation and warming climate.On the spatial scale,by studying the changes in vegetation distribution in the “east-west” and “south-north” section directions,it is found that the change in the impact distance of the mining area on the surrounding vegetation has an obvious "increasing first and then decreasing" characteristic.The development of the mining area has less impact on the surrounding Karamayri Nature Reserve and the Jimusar Desert.Therefore,further analysis of the vegetation distribution and change heterogeneity in the mining area,it is found that after mining in the mining area,the spatial concentration of vegetation distribution in the mining area is strengthened,and the spatial vegetation variation coefficient is increased;The horizontal vegetation accumulation phenomenon mainly occurs around the mining area and shifts to the center of the mining area.As the vegetation recovers,a spatial pattern of high-level vegetation surrounding low-level vegetation is gradually formed.Desert vegetation in arid areas is sensitive to changes in nitrogen.The development of coal carbon resources will make the mining area a huge source of atmospheric nitrogen.This article uses OMI-NO2 data to invert the atmospheric nitrogen deposition.Through the analysis of the changes in atmospheric nitrogen deposition and the vegetation and precipitation in the mining area,the impact of changes in nitrogen deposition on the mining area and its surroundings on vegetation is analyzed.The results show that After mining in the mining area,the increase of nitrogen deposition has a certain promotion effect on vegetation change.