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首页> 外文期刊>Biogeosciences >Edaphic, structural and physiological contrasts across Amazon Basin forest–savanna ecotones suggest a role for potassium as a key modulator of tropical woody vegetation structure and function
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Edaphic, structural and physiological contrasts across Amazon Basin forest–savanna ecotones suggest a role for potassium as a key modulator of tropical woody vegetation structure and function

机译：亚马逊盆地森林 - 大草原生态藻酮的助理，结构和生理对比表达了钾作为热带木质植被结构和功能的关键调制器的作用

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Sampling along a precipitation gradient in tropical South America extending from ca. 0.8 to 2.0 m a?1, savanna soils had consistently lower exchangeable cation concentrations and higherC / N ratios than nearby forest plots. These soil differences were also reflected in canopy averaged leaf traits with savanna trees typically having higher leaf mass per unit area but lower mass-based nitrogen (Nm) and potassium (Km). Both Nm and Km also increased with declining mean annual precipitation (PA), but most area-based leaf traits such as leaf photosynthetic capacity showed no systematic variation with PA or vegetation type. Despite this invariance, when taken in conjunction with other measures such as mean canopy height, area-based soil exchangeable potassium content, [K]sa , proved to be an excellent predictor of several photosynthetic properties (including 13C isotope discrimination). Moreover, when considered in a multivariate context with PA and soil plant available water storage capacity (θP) as covariates, [K]sa also proved to be an excellent predictor of stand-level canopy area, providing drastically improved fits as compared to models considering just PA and/or θP. Neither calcium, nor magnesium, nor soil pH could substitute for potassium when tested as alternative model predictors (ΔAIC > 10). Nor for any model could simple soil texture metrics such as sand or clay content substitute for either [K]sa or θP. Taken in conjunction with recent work in Africa and the forests of the Amazon Basin, this suggests – in combination with some newly conceptualised interacting effects of PA and θP also presented here – a critical role for potassium as a modulator of tropical vegetation structure and function.
机译：从加利福尼亚州的热带南美洲沿着降水梯度取样。 0.8至2.0米的？1 ，Savanna土壤始终较低的可交换阳离子浓度和比附近的森林图更低的阳离子浓度和uperc / n比率。这些土壤差异也反映在冠层平均叶状性状的叶状性状，其中大草原树木通常具有较高的叶片，单位面积较高，但基于低质量的氮气（n m ）和钾（k m ）。 n m 和k m 也随着平均年降水量下降而增加（ p a ），但大多数区域 - 基于叶片光合容量的叶状性状显示没有系统变化，具有 P 或或植被类型。尽管这种不变性，当与其他措施如平均冠层高度，面积的土壤可交换的钾含量相结合时，被证明是几种光合特性的优异预测因子（包括< sup> 13 c同位素辨别）。此外，当用 p a 和土壤储存容量（θ p ）作为协变量，[k] < SA SA 也被证明是架型冠层区域的优异预测因子，与考虑仅仅 p a 和/或θ p 。当作为替代模型预测器（ΔIC> 10）测试时，缺乏钙，也不是土壤pH可以替代钾的钾。对于任何模型，也可以简单的土壤纹理度量，例如砂或粘土含量替代[k] sa 或θ p 。这与近期工作以及亚马逊盆地的森林一起进行，这表明 - 与 p a 和θ p的一些新概念化相互作用效果相结合在此提出 - 钾作为热带植被结构和功能调制器的关键作用。

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