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

机译：亚马逊河流域森林与热带稀树草原过渡带之间的粗化，结构和生理对比表明钾是热带木本植被结构和功能的关键调节剂

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pstrongAbstract./strong Sampling along a precipitation gradient in tropical South America extending from ca. 0.8 to 2.0 m asupa??1/sup, savanna soils had consistently lower exchangeable cation concentrations and higher C / 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 (Nsubm/sub) and potassium (Ksubm/sub). Both Nsubm/sub and Ksubm/sub also increased with declining mean annual precipitation (iP/isubA/sub), but most area-based leaf traits such as leaf photosynthetic capacity showed no systematic variation with iP/isubA/sub 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]subsa/sub , proved to be an excellent predictor of several photosynthetic properties (including sup13/supC isotope discrimination). Moreover, when considered in a multivariate context with iP/isubA/sub and soil plant available water storage capacity (θsubP/sub) as covariates, [K]subsa/sub also proved to be an excellent predictor of stand-level canopy area, providing drastically improved fits as compared to models considering just iP/isubA/sub and/or θsubP/sub. 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]subsa/sub or θsubP/sub. Taken in conjunction with recent work in Africa and the forests of the Amazon Basin, this suggests a?? in combination with some newly conceptualised interacting effects of iP/isubA/sub and θsubP/sub also presented here a?? a critical role for potassium as a modulator of tropical vegetation structure and function./p.
机译：> >摘要。沿热带降水的采样从南美洲热带地区开始。与附近的林地相比，从0.8到2.0 m a a ?? 1 ，稀树草原土壤的可交换阳离子浓度和C / N比值始终较低。这些土壤差异也反映在冠层平均叶片性状上，热带稀树草原通常具有较高的单位面积叶片质量，但基于质量的氮（N m ）和钾（K m ）。 N m 和K m 均随着年均降水量（ P A ）的减少而增加，但大多数地区-叶片的光合能力等基础性状随 P A 或植被类型无系统变化。尽管存在这种不变性，但与其他措施（例如平均冠层高度，基于区域的土壤可交换钾含量[K] sa ）结合使用时，仍然可以很好地预测几种光合特性（包括< sup> 13 C同位素判别）。此外，在多变量环境中以 P A 和土壤植物的可用水储水量（θ P ）作为协变量时，[K]与仅考虑 P A 和/的模型相比， sa 还被证明是站立水平林冠面积的极佳预测指标，与之相比，其拟合度得到了显着改善。或＆theta; P 。当作为替代模型预测指标进行测试时，钙，镁，土壤pH都不能替代钾（ΔAIC> 10）。对于任何模型而言，简单的土壤质地指标（例如沙子或粘土含量）都无法代替[K] sa 或＆theta; P 。结合非洲和亚马逊河流域森林的最新工作，这表明？结合 P A 和＆theta; P 的一些新概念化的相互作用，在此还提出了一个？钾在调节热带植被结构和功能中的重要作用。

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