Stability of the alpine grassland vegetation ecosystem in open-pit mining area at the southern Qilian Mountains——A case study in Muli-Juhugeng mining area,Qinghai Province
The ecological security issues in alpine grassland mining areas have always been of great concern.Conducting research on the stability of vegetation ecosystems in alpine grassland mining areas can deeply reveal the impact of open-pit mining activities and ecological restoration projects on the vegetation ecosys-tems in alpine grassland mining areas.Taking the Qinghai Muli-Juhugeng mining area at the southern foot of the Qilian Mountains as the research area,a total of nine Landsat remote sensing images from 2002-2022 were analyzed from before coal mining to after restoration.Grid processing was based on normalized difference vegetation index(NDVI)data,with NDVI mean(μ)、mean square deviation(σ)and relative fluc-tuations(δ).Based on three vegetation stability indices,a study was conducted on the impact of open-pit coal mining and remediation processes on the stability of alpine grassland vegetation ecosystems in mining areas.The study revealed the variability and stability characteristics of alpine grassland vegetation ecosys-tems throughout the entire life cycle from coal mining to remediation,and compared the effectiveness of two ecological remediation processes.The higher the relative fluctuation value,the more unstable the vege-tation ecosystem is.If the relative fluctuation value continues to exceed the background threshold,the vege-tation ecosystem is unstable.The results are as follows:①The vegetation system in the natural grassland background area of the mining area is in a macro stable state,with the NDVI relative fluctuation value δ<0.45;②Compared with the background area,the relative fluctuation of NDVI in the mining area has signif-icantly increased after coal mining,with a difference of up to 0.97 compared to the background area,indica-ting the instability of the vegetation ecosystem in the mining area;③After the first restoration and control in 2015-2017,the relative fluctuation of NDVI in the mining area is not effectively reduced by 0.28<δ<1.10,and the restoration effect of soil covering and artificial planting in alpine grassland areas is not signifi-cant;④After the second restoration and control from 2020-2022,the stability of the vegetation ecosystem in the mining area has significantly improved,and the relative fluctuation value of the control area has de-creased to a level similar to that of the background area(δ=0.07-0.59),and the stability order of the veg-etation ecosystem in the mining area is:pit bottom>pit slope>slag mountain in the mining area;⑤Soil im-provement has significantly improved the stability of vegetation ecosystems under various terrain condi-tions,promoting positive vegetation succession.Terrain is the main factor affecting the ecological restora-tion of vegetation in mining areas.By optimizing the management measures of abandoned hills and shaded slopes,the restoration efficiency of damaged vegetation ecosystems in mining areas can be further im-proved.The results can provide a scientific basis for the rational development and ecological construction of alpine grassland mining areas in China.
alpine meadowstability of vegetation ecosystemanalysis of spatiotemporal data seriesnormal-ized difference vegetation indexrelative fluctuationMuli-Juhugeng mining area