Impact of Coal Mining Subsidence on Sandy Geomorphology and Vegetation Habitat in Sandy Area

[Objectives] To explore the problem of “secondary desertification” caused by coal mining subsidence in sandy area and its control countermeasures. [Methods] The collapse fissure changes, vegetation displacement and tilt, dry sand layer and wind erosion/aeolian deposit rate of the edge, middle and basin of subsidence area were studied in detail. [Results] The width and density of fissures at the edge of subsidence area were the smallest, followed by those in the center, and the width and density of fissures in the basin of the subsidence area were the greatest, while the staggering and surface damage showed the opposite trend. The average displacement length of vegetation in the subsidence area reached 60 cm, the slope was 5.67-28.63, and the maximum wind erosion/aeolian deposit at the trunk roots was -30.52 cm/+25.41 cm, most serious at the edge of subsidence. The changes in displacement length and slope of vegetation were positively linearly correlated with the height and surface damage of collapse fissures. The thickness of dry land layer at the edge of the subsidence area reached 14 cm, 4-6 cm greater than that of the control, and the thickness of dry land layer in the middle and basin of the subsidence area was both about 11 cm, 1-4 cm greater than that of non-subsidence area. The wind erosion rate at the edge of the subsidence area was up to 83.34%, followed by that (52.06%) in the middle. The aeolian deposit rate in the subsidence basin was 51.84%. [Conclusions] The subsidence edge has the strongest impact on the sandy geomorphology and vegetation habitat, and is a key area for ecological restoration. It is recommended that the coal mining subsidence should be treated in a timely manner to avoid the occurrence of “secondary desertification”.