BACKGROUND AND AIMS The aim of this study was to test the frequency distributions of foliar elements from a large dataset from Kinabalu Park (Sabah, Malaysia) for departure from unimodality, indicative of a distinct ecophysiological response associated with hyperaccumulation. METHODS We collected foliar samples (n = 1533) comprising 90 families, 198 genera and 495 plant species from ultramafic soils, and foliar samples (n = 177) comprising 45 families, 80 genera and 120 species from non-ultramafic soils and corresponding soil samples (n = 393 from ultramafic soils and n = 66 from non-ultramafic soils) from Kinabalu Park (Sabah, Malaysia). The data were geographically- (Kinabalu Park) and edaphically- (ultramafic soils) constrained. The inclusion of a relatively high proportion (~14%) of samples from hyperaccumulator species (with foliar concentrations of Al, Ni >1000 μg g-1, Co, Cu, Cr, Zn >300 μg g-1 or Mn >10 mg g-1) allowed for hypothesis testing. KEY RESULTS Frequency distribution graphs for most elements (Ca, Mg, P) were unimodal, although some were skewed left (Mg, Mn). The Ni frequency distribution was bimodal and the separation point for the two modes was between 250-850 μg g-1. CONCLUSIONS Accounting for statistical probability, the established empirical threshold value (>1000 μg g-1) remains appropriate. The two discrete modes for Ni indicate ecophysiologically distinct behaviour in plants growing in similar soils. This response is in contrast with Mn, which forms the tail of a continuous (approximately log-normal) distribution, suggestive of an extension of normal physiological processes.

中文翻译：

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京那巴鲁公园（马来西亚沙巴）超镁铁质植物群中叶面镍的频率分布呈双峰分布


背景和目的本研究的目的是测试京那巴鲁公园（马来西亚沙巴）大型数据集中叶元素的频率分布是否偏离单峰，表明与超积累相关的独特生态生理反应。方法我们从超镁铁质土壤中采集了包含 90 科、198 属、495 种植物的叶样（n = 1533），以及从非超镁铁质土壤和相应土壤样品中采集了包含 45 科、80 属、120 种植物的叶样（n = 177）。 （n = 393 个来自超镁铁质土壤，n = 66 个来自非超镁铁质土壤）来自京那巴鲁公园（马来西亚沙巴）。数据受到地理（京那巴鲁公园）和土壤（超镁铁质土壤）的限制。包含相对较高比例 (~14%) 的超积累物种样品（Al、Ni 的叶面浓度 >1000 μg g-1，Co、Cu、Cr、Zn >300 μg g-1 或 Mn >10 mg g-1) 允许进行假设检验。主要结果 大多数元素（Ca、Mg、P）的频率分布图都是单峰的，尽管有些元素（Mg、Mn）是左偏的。 Ni 频率分布是双峰的，两种模式的分离点在 250-850 μg g-1 之间。结论 考虑到统计概率，建立的经验阈值（>1000 μg g-1）仍然是合适的。 Ni 的两种离散模式表明在相似土壤中生长的植物具有不同的生态生理行为。这种反应与 Mn 形成鲜明对比，Mn 形成连续（近似对数正态）分布的尾部，表明正常生理过程的延伸。