Effects of underground mining on vegetation and environmental patterns in a semi-arid watershed with implications for resilience management

Abstract

A rapid increase in underground mining in a semi-arid area of China has led to serious concerns about the health of vegetation overlying these coal seams. However, there have been no empirical studies to illustrate the response and persistence of surface vegetation in these underground mining areas. A combination of field assessments with remote sensing was used to examine vegetation patterns and responses to underground mining, while laying a foundation for environmental protection. The study area lies in a vulnerable watershed exposed to hazards caused by underground coal mining, located on the southern edge of Inner Mongolia in China. The results demonstrate that hydrological factors and soil attributes, including groundwater levels, soil organic matter, and soil moisture, control the structure of the local vegetation community. After mining begins, the vegetation community index based on plant density, coverage, and biomass in areas affected by subsidence fractures decreases by 0–21.5%. Nevertheless, the average Normalized Differential Vegetation Index at the entire watershed scale increased by 15% from 2001 to 2016, although this change appeared to be primarily related to rainfall. This study confirmed that underground coal mining in the watershed has not caused extensive vegetation degradation as feared. Positive climatic trends, the maintenance of important mudstone strata below a phreatic aquifer and the adaptation of vegetation to drought, contributed to the persistence of surface vegetation in underground mining areas. Considering that mining activities usually last for several years, resilience management, including approaches such as protection of important variables, long-term monitoring, and adaptive management, should be adopted in support of conservation and sustainable mining in this watershed and at similar mine sites.