Abstract Understanding the patterns of vegetation establishment on rehabilitated mine tailings is critical in evaluating the effectiveness of rehabilitation programs, but is still largely unknown. The concept of formation of fertility islands and their effect on vegetation establishment on two rehabilitated nickel mine tailings of different ages (20 and 40 years) since last depositions in tropical Zimbabwe was investigated to compare: (1) the tailings physicochemical properties: nitrogen (N), phosphorus (P), potassium (K), organic matter (OM), calcium (Ca), pH, salinity, texture and bulk density between perceived fertility islands (tree-canopy sites) and off- canopy sites, (2) vegetation structural and compositional attributes of canopy and the adjacent off-canopy sites, on the two tailings dumps, and, (3) to identify substrate correlates to observed vegetation attributes. We hypothesized that: (1) total N, Mineral N, OM and available P were significantly higher on canopy than adjacent off- canopy sites, (2) vegetation cover and species richness were higher on canopy than on off-canopy sites, and, (3) dump age and tree species had significant effect on substrate and vegetation attributes. We sampled substrate and vegetation in 1 m2 quadrats laid under planted tree canopies and the adjacent off-canopy sites on tailings dumps that were rehabilitated by planting leguminous trees. The Factorial ANOVA test showed that dump age and tree species had no significant effect on substrate properties and vegetation attributes. Mineral N, total N, available P, OM, and clay content were significantly higher on canopy than on the adjacent off-canopy sites while bulk density was significantly lower on canopy than on off-canopy sites. All vegetation structural attributes (overall plant aerial cover, grass cover, forb cover, woody seedlings cover and tuft density), species richness were significantly higher on canopy than on off-canopy sites. Plant communities on canopy sites were distinct from those on off-canoppy sites, regardless of dump age. Results demonstrate the ecological engineering potential of the leguminous trees through creating fertility islands that influence understory vegetation establishment on mine tailings.

中文翻译：

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豆科树种造成肥力岛，影响不同年代镍矿尾矿的林下植被

摘要 了解已修复尾矿的植被建立模式对于评估修复计划的有效性至关重要，但在很大程度上仍是未知数。研究了自上次在津巴布韦热带地区沉积以来不同年龄（20 年和 40 年）的两个恢复镍矿尾矿的肥力岛形成概念及其对植被建立的影响，以比较：（1）尾矿理化性质：氮（N )、磷 (P)、钾 (K)、有机质 (OM)、钙 (Ca)、pH、盐度、质地和感知肥力岛（树冠地点）和冠层外地点之间的体积密度，（2）两个尾矿堆上冠层和邻近冠层外场地的植被结构和组成属性，以及，(3) 识别与观察到的植被属性相关的基质。我们假设：(1) 冠层上的总氮、矿物质 N、OM 和有效磷显着高于邻近冠层外的地点，(2) 冠层上的植被覆盖度和物种丰富度高于冠层外的地点，并且， (3)垃圾场龄和树种对基质和植被属性有显着影响。我们在种植的树冠下以及通过种植豆科植物修复的尾矿场附近的树冠外的 1 平方米样方中对基质和植被进行了采样。因子方差分析表明，垃圾场年龄和树种对基质特性和植被属性没有显着影响。矿物氮，总氮，有效磷，有机磷，冠层上的粘土含量显着高于冠层外相邻站点，而冠层上的容重显着低于冠层外站点。所有植被结构属性（整体植物空中覆盖、草覆盖、杂草覆盖、木本幼苗覆盖和簇丛密度）、物种丰富度在冠层上均显着高于冠层外。无论倾倒年龄如何，冠层上的植物群落都与冠层外的植物群落不同。结果通过创建影响尾矿下层植被建立的肥力岛来证明豆科植物的生态工程潜力。木本幼苗覆盖率和簇密度），冠层上的物种丰富度显着高于冠层外。无论倾倒年龄如何，冠层上的植物群落都与冠层外的植物群落不同。结果通过创建影响尾矿下层植被建立的肥力岛来证明豆科植物的生态工程潜力。木本幼苗覆盖率和簇密度），冠层上的物种丰富度显着高于冠层外。无论倾倒年龄如何，冠层上的植物群落都与冠层外的植物群落不同。结果通过创建影响尾矿下层植被建立的肥力岛来证明豆科植物的生态工程潜力。