Background and aims

Ultramafic soils have high metal concentrations, offering a key opportunity to understand if such metals are strong predictors of leaf stoichiometry. This is particularly relevant for tropical forests where large knowledge gaps exist.

Methods

On the tropical island of Sulawesi, Indonesia, we sampled forests on sand, limestone, mafic and ultramafic soils that present a range of soil metal concentrations. We asked how variation in 12 soil elements (metals and macronutrients) influenced leaf stoichiometry and whether stoichiometric distinctiveness (the average difference between a species and all others in a multivariate space, the axes of which are the concentrations of each leaf element) is influenced by increasing soil metal concentrations.

Results

Positive correlations between corresponding elements in soils and leaves were only found for Ca and P. Noticeably, soil Cr had a negative effect upon leaf P. Whilst most species had low stoichiometric distinctiveness, some species had greater distinctiveness on stressful metal-rich ultramafic soils, generally caused by the accumulation of Al, Co, Cr or Ni.

Conclusions

Our observation of increased stoichiometric distinctiveness in tropical forests on ultramafic soils indicates greater niche differentiation, and contrasts with the assumption that stressful environments remove species with extreme phenotypes.

中文翻译：

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富含金属的土壤增加了热带树木化学计量的独特性

背景和目标

超镁铁质土壤中的金属含量很高，这为了解此类金属是否是叶片化​​学计量的强预测指标提供了重要机会。这对于存在大量知识缺口的热带森林尤其重要。

方法

在印度尼西亚苏拉威西岛的热带岛屿上，我们在沙滩，石灰石，镁铁矿和超镁铁矿土壤上取样了森林，这些土壤表现出各种土壤金属浓度。我们询问了12种土壤元素（金属和大量营养素）的变化如何影响叶片的化学计量，以及化学计量的独特性（物种与所有其他物种在多元空间中的平均差异，其轴是每个叶片元素的浓度）是否受到以下因素的影响：增加土壤金属浓度。

结果

土壤和叶片中相应元素之间的正相关仅针对钙和磷。值得注意的是，土壤铬对叶片P产生负面影响。虽然大多数物种的化学计量特征低，但某些物种在富金属的超镁铁质土壤中具有较大的特征，通常由Al，Co，Cr或Ni的积累引起。

结论

我们在超镁铁质土壤上热带森林中化学计量比独特性增加的观察结果表明，生态位分化更大，并且与压力环境去除具有极端表型物种的假设形成对比。