Ecological restoration effect evaluation of Zhangxuan iron tailings in Hebei Province of northern China under different vegetation patterns

  Objective  To explore the effects of different vegetation restoration patterns on ecological restoration effects in iron ore abandoned sites, suitable vegetation restoration patterns were selected to solve the problems of low soil nutrients, plant growth difficulties and serious soil and water loss in abandoned iron tailings land.

  Method  Fourteen types of vegetation restoration patterns of iron tailings ponds in Zhangxuan mining area of Hebei Province, northern China were studied. The vegetation growth characteristics, species composition and plant diversity characteristics, soil nutrients and other indicators were selected to compare their restoration effects in order to screen out suitable vegetation restoration patterns in the area.

  Result  The vegetation coverage of all patterns was generally at the middle and upper level, and Pinus tabuliformis, Hippophae rhamnoides, Phragmites communis and Artemisia lavandulaefolia were the dominant species of tree, shrub and herb in the study area, respectively. The diversity index of tree and tree + shrub patterns were generally higher than that of shrub and shrub + herb, but the richness index was generally poor. Different vegetation restoration patterns and soil depths all had significant effects on soil nutrients. The soil was rich in fast-acting potassium (K), but low in phosphorus (P), nitrogen (N) and organic matter in the area. According to CRITIC-GRA model, the top three patterns in the study area were Pinus tabuliformis, Pinus tabuliformis + Fraxinus pennsylvanica and Hippophae rhamnoides + Lespedeza bicolor, which were all evaluated as “excellent”; among all the restoration measures, only the natural restoration measures were evaluated as “poor”.

  Conclusion  It is suggested to adopt soil covering for seedling restoration, and give priority to Pinus tabuliformis + Hippophae rhamnoides or Lespedeza bicolor + Artemisia lavandulaefolia or Melilotus officinalis in plant species selection. In addition, appropriate amount of nitrogen and phosphate fertilizer or organic fertilizer can be applied to accelerate soil nutrient improvement of iron tailing pond.