Impacts of Underground Coal Mining on the Roots of Xeromorphic Plant: A Case Study

Abstract

The ground movement induced by underground mining operation affects or even damages the roots of land plants with resultant vegetation deterioration. The adaptability of land plant to mining disturbance is species dependent. In this study, several typical xeromorphic plants growing in Shendong Coalfield, an arid and semiarid area of northwestern China, were compared in terms of root distribution and lengths. Distinct element method-based models were established to investigate the evolution of stress and deformation of topsoil during underground coal excavation, indicating that incongruous dislocations associated with tensile or shear deformation of soil blocks contribute to the negative effects on the roots of land plant. Furthermore, in the same scenario of deep-seated coal seam extraction, numerical modeling with more sophisticated topsoil blocks and plant roots visually indicated that most parts of the vertical root cracked, while pivotal parts of horizontal roots remained almost intact. Field data of vegetation communities in unexploited and exploited areas at two coal mines of Shendong Coalfield in terms of the coverage, density, and frequency, which showed a good agreement with modeling results, reveal that plants with more developed horizontal roots have stronger adaptability to mining disturbance, and should be cultivated more to become the dominant species in coal mining areas.