| Ecological restoration of surface coal mines is key to meet global ecosystem restoration target.Simultaneous monitoring of the restoration process of multiple surface coal mines on a large scale can help assess the overall restoration status of mines in the region and understand the regularity of ecological restoration.With the improvement of data accessibility and the development of data processing capabilities,it has become possible to extend the monitoring of mine ecological restoration from a single mine site to multiple mine sites on a large scale.Based on the MODIS global disturbance index(MGDI),this study proposed the mine landscape restoration index(MLRI),by coupling Land surface temperature(LST)and Enhanced vegetation index(EVI).And the MLRI has been applied to monitor ecological restoration in multiple mine sites on a large scale.The restoration process was analyzed by Mann-Kendall test and Sen’s slope,and the areas with significant increase in MLRI values were identified as restoration areas.The future trend of MLRI time series was analyzed by Hurst index analysis,and the areas with significant consistent increase in MLRI and significant anti-consistence increase in MLRI were considered as consistent restoration areas and anti-consistence restoration areas.Based on 3675 Landsat images on the Google earth engine platform,this study monitored the restoration process of 46 surface mine sites located in north China from 2000 to 2019.The restoration effects of mine sites were characterized by the proportion of consistent restoration areas and anti-consistence restoration areas of mine sites,the climatic influences on the restoration effect were explored,and mine restoration strategies were proposed.The main results are as follows.(1)The specific process of MLRI time series construction,restoration area identification and classification are demonstrated for the Antaibao&Anjialing and Shenglixi III surface mine sites.The overall recognition accuracy was 0.94 for the Antaibao&Anjialing mine site and 0.95 for the Shenglixi III mine site,and the kappa coefficients were 0.88 and 0.81 for the two mine sites,respectively.The MLRI time series analysis can effectively identify the restoration areas and characterize the restoration effect of the mine sites.(2)From the restoration effects of the 46 mining areas,the duration of mining and precipitation were positively correlated with the restoration effects,and the dryness was negatively correlated with the restoration effects,and the proportion of the total area of the restored area was significantly higher in the mining areas that started mining before 2000 than in the mining areas after 2000.Based on the proportion of the area of sustained restoration area and anti-sustained restoration area to the area of the mine,this study divided 46 mining areas into three clusters of high,medium,and low restoration area percentages.The three clusters contained 13,11 and 22 mining areas,respectively.In terms of spatial distribution,the mining areas with high restoration percentages were mainly distributed in the six open-pit coal mining agglomerations in the Shengli&Holinghe and Jin&Shaan&Meng regions.The mines with medium and low restoration ratios were mainly distributed in the Hailar,Shengli&Holinghe,Yuanbaoshan,Jin&Shaan&Meng,and Zhuozishan&Luoshan regions,while the restoration ratios of the mines in the Zhunnan region were all low.This study provides a new method for restoration monitoring of multiple mine sites on a large scale and evaluates the ecological restoration effects of 46 surface mine sites in north China from2000-2019,providing a reference for decision makers to develop regional mine restoration programs and sustainable mining development plans. |
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