Screening of Suitable Ecological Restoration Species for Tailings Ponds Oriented towards the Construction of Ecological Security Barriers

Vegetation greening of tailings ponds and the construction of surrounding shelterbelt systems are essential components of building a regional ecological security barrier using a "point-line-plane" framework. However, due to the unique nature of industrial and mining land and harsh site conditions, research on selecting suitable plant species for tailings pond areas lags behind, hindering the efficient establishment of pollution- and dust-control forests and ecological restoration efforts. For many years, Hyperaccumulator plants have been believed to be capable of removing heavy metals from contaminated soils such as tailings wastelands and contaminated farmlands. However, how to carry out ecological restoration with suitable species as carriers at both the scale of tailings ponds and surrounding areas urgently needs further exploration based on the theory of "target positioning-technical efficiency-functional improvement" for the coordinated control of ecological restoration and pollution control in mining areas. This study takes an iron ore tailings pond in the Yangtze River Delta region as an example. Through vegetation community surveys and topographic factor measurements across four site types "pond surface, upper slope, middle slope, lower slope" the composition of plant species, changes in plant diversity, and the influence of microtopography in the vegetated areas were analyzed. The results show that: (1) A total of 69 plant species were found in the vegetated areas of the tailings pond, belonging to 20 families and 53 genera, primarily from the Fabaceae, Poaceae, Asteraceae, Rosaceae, and Polygonaceae families, accounting for 71% of the total. (2) Herbs and shrubs were the dominant plant types, while trees likely established naturally from seeds dispersed by wind from external sources. Representative dominant plants include Setaria viridis, Miscanthus sinensis, Themeda triandra, and Solidago canadensis. (3) Vegetation coverage in the tailings pond was negatively correlated with elevation (P < 0.01), with higher coverage observed on middle and lower slopes. Slope gradient showed a positive correlation with species richness, Shannon-Wiener index, Simpson diversity index, and Pielou evenness index (P < 0.01). (4) A multi-scale ecological barrier for tailings ponds should be constructed by integrating the "point-line-plane" approach. For vegetation configuration at the "point" scale (the tailings pond itself), priority should be given to hyperaccumulator plants and heavy metal-tolerant species with strong vitality and rapid growth, such as Poaceae and Asteraceae, on the pond surface. On slopes, taller Poaceae plants should be combined with perennial shrubs like Robinia pseudoacacia (Fabaceae) to enhance species richness. The findings of this study provide a germplasm resource reference for the ecological restoration of tailings ponds and offer a scientific basis for optimizing plant species configuration in the construction of ecological barriers in mining areas.