面向生态安全屏障构建的尾矿库适宜生态修复物种筛选

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

  • 摘要: 尾矿库植被绿化与周边防护林体系建设是"点-线-面"构建区域生态安全屏障的重要内容。然而, 由于工矿用地性质特殊及立地条件恶劣, 尾矿库区适宜植物种筛选研究相对滞后, 制约了防污滞尘林的高效营建与生态修复进程。多年来, 富集植物被认为可移除尾矿废弃地、受污染耕地等污染土壤的重金属, 但如何面向尾矿库和周边区域两个尺度进行生态修复, 亦亟待基于"目标定位-技术高效-功能提升"的矿区生态修复与污染治理协同控制理论进行进一步探究。为此, 本文以长三角地区某铁矿尾矿库为例, 通过库面、上坡、中坡、下坡4个立地类型恢复植被的群落调查与地形因子测定, 分析了植被绿化区植物种组成和植物多样性变化及微地形的影响。结果表明: (1)尾矿库植被绿化区共发现植物69种, 隶属于20科53属, 以豆科、禾本科、菊科、蔷薇科和蓼科为主, 植物种数占比达71%。(2)草本和灌木是主要植物种, 乔木可能是种子在风媒作用下由外部传播而自然定居, 狗尾草、芒、阿拉伯黄背草、加拿大一枝黄花是具有代表性的优势植物。(3)尾矿库植被盖度与高程呈负相关(P < 0.01), 中下坡的植被盖度较高。坡度与物种丰富度、Shannon-Wiener指数、Simpson多样性指数、Pielou均匀度指数均呈正相关(P < 0.01)。(4)综合运用"点-线-面"相结合的思路构建多尺度尾矿库生态屏障, 在尾矿库"点"上进行植被配置时, 库面应优先考虑生命力强且生长迅速的禾本科、菊科等超富集植物和重金属耐性植物, 边坡上应种植较高大的禾本科植物并搭配刺槐等豆科多年生灌木用以提升边坡的物种丰富度。研究结果为尾矿库生态修复提供了种质资源参考, 为矿区生态屏障建设的植物种优化配置提供了科学依据。

     

    Abstract: 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.

     

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