Ailanthus altissima is one of the major invasive trees at a global scale. Despite numerous reports about its invasiveness in different habitats, so far it was not observed on harsh ultramafic soils and to colonize the vegetation of these outcrops. In this paper we show that the species can also spread in these habitats in the Mediterranean region and is able to cope with the severe anomalies of ultramafic soils. We sampled A. altissima in four ultramafic outcrops of central Italy and in control sites to unravel the behavior of this species toward the typically high soil concentrations of trace metals, such as Ni, Cr and Co, as well the imbalance of the Ca:Mg quotient. A similar sampling was performed for the native Fraxinus ornus that occurs naturally on a broad range of soils, including those from ultramafic rocks. Trace metal concentrations in leaves of both species were below toxicity thresholds, but A. altissima showed lower translocation and bioaccumulation factors (TF and BF, respectively) for Ni. Compared with F. ornus, the invasive species displayed higher leaf concentrations of Mg, thus suggesting a higher tolerance of potentially toxic levels of this element. Moreover, the higher TF and BF values for Ca in both control and serpentine populations suggested that A. altissima was more able to extract and accumulate this macronutrient in leaves in respect to F. ornus. Given the inherent deficiency of this element in ultramafic soils, efficient use of Ca could be a key trait contributing to the invasiveness of A. altissima on these soils.

中文翻译：

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超镁铁质土壤上入侵臭椿与原生水曲柳中的金属浓度：镍排除和调整镁和钙失衡效率更高的证据

臭椿是全球范围内主要的入侵树木之一。尽管有大量关于其在不同栖息地的入侵的报道，但到目前为止，尚未在恶劣的超镁铁质土壤上观察到它并在这些露头的植被上定居。在本文中，我们表明该物种也可以在地中海地区的这些栖息地中传播，并且能够应对超镁铁质土壤的严重异常。我们采样了臭椿在意大利中部的四个超镁铁质露头和对照地点，以揭示该物种对微量金属（例如镍、铬和钴）典型高土壤浓度以及钙镁商不平衡的影响的行为。对本地人进行了类似的抽样白蜡树它自然发生在多种土壤中，包括来自超镁铁岩的土壤。两个物种叶子中的痕量金属浓度均低于毒性阈值，但臭椿显示出较低的 Ni 易位和生物累积因子（分别为 TF 和 BF）。和....相比奥努斯，入侵物种的叶子中镁浓度较高，因此表明对该元素的潜在毒性水平具有更高的耐受性。此外，对照和蛇纹石种群中 Ca 的 TF 和 BF 值较高，表明臭椿能够在叶子中提取和积累这种常量营养素奥努斯。鉴于超镁铁质土壤中这种元素的固有缺乏，钙的有效利用可能是导致铁性土壤入侵的一个关键特征。臭椿在这些土壤上。