摘要:草原采矿活动疏排地下水导致区域地下水位下降，植被退化严重。明确草原采矿活动影响区域地下水位埋深的强度和范围，确定影响植被生长的地下水位埋深阈值，对草原矿区生态环境保护有着重要意义。以呼伦贝尔草原伊敏露天煤矿为例，利用遥感方法，建立采矿前后区域地下水埋深变化与NDVI的定量响应关系；通过样方调查，确定研究区植被群落随地下水位埋深变化的演替模式，分析草原矿区地下水位变化对草原植被类型、物种丰富度、植被覆盖度、地上生物量和综合优势比的影响；结合两种方法，确定维持研究区植被正常生长的地下水位埋深阈值。其结果如下：从柴达敏诺尔湖至采坑边缘，地下水位埋深从0 m逐渐下降至60 m，植被群落演替为盐化草地→典型草原→退化典型草原→退化草甸草原→盐化草甸草原；研究区最适宜植被生长的地下水位埋深约为1 m；1-30 m为维持研究区植被正常生长的阈值地下水位埋深。最后根据以上结论，将研究区划分为地下水开发的一级敏感区、二级敏感区和三级敏感区，针对不同敏感区提出了不同的地下水开发政策，以防止采矿活动疏排地下水引起草原退化。



Abstract:The drainage of groundwater caused by grassland mining activities leads to the decrease of groundwater level, which caused a dramatic degradation of grassland vegetation in surounding area. Understanding how grassland mining activities impact on the intensity and range of groundwater depth, determining threshold of depth to the groundwater table for vegetation growth would be a crucial prerequisite to protect the ecological environment of grassland mining area. In this study, Yimin open-pit coal mine in Hulun Buir grassland was investigated as an example. By introducing remote sensing method, the quantitative response relationship between depth to the groundwater table and Normalized Difference Vegetation Index (NDVI) before and after mining was established. How the composition of vegetation community change to the groundwater level and how the depth to the groundwater table influence the vegetation in terms of types, species richness, vegetation coverage, aboveground biomass and summed dominance ratio in grassland mining areas was determined by analyzing the data of sample survey. Further, combined with the results from two methods, the threshold of depth to the groundwater table for maintaining the normal growth of vegetation in the study area was determined.The results are as follows: From Chedaminol Lake to the edge of the mining pit, the depth to the groundwater table decreased gradually from 0 m to 60 m, and the vegetation community was successively from salinized grassland to typical grassland to degraded grassland to degraded meadow grassland to salinized meadow grassland. A depth to the groundwater table of about 1 m was most suitable for growing vegetation; A depth to the groundwater table of 1-30 m was the threshold to maintain the normal vegetation growth in the study area. Finally, according to the above conclusion, the study area is divided into the first sensitive area, the second sensitive area and the third sensitive area and corresponding policy recommendations were proposed for different sensitive areas.





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