Evolution and Ecology Research Centre, School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney, NSW 2052, Australia;
Department of Biological Sciences, Macquarie University, Sydney, NSW 2109, Australia.
Proc Natl Acad Sci U S A. 2018 Jul 17;115(29):E6789-E6798. doi: 10.1073/pnas.1714044115. Epub 2018 Jun 29.
Plant species differ in many functional traits that drive differences in rates of photosynthesis, biomass allocation, and tissue turnover. However, it remains unclear how-and even if-such traits influence whole-plant growth, with the simple linear relationships predicted by existing theory often lacking empirical support. Here, we present a theoretical framework for understanding the effect of diverse functional traits on plant growth and shade tolerance by extending a widely used model, linking growth rate in seedlings with a single leaf trait, to explicitly include influences of size, light environment, and five prominent traits: seed mass, height at maturation, leaf mass per unit leaf area, leaf nitrogen per unit leaf area, and wood density. Based on biomass growth and allocation, this framework explains why the influence of traits on growth rate and shade tolerance often varies with plant size and why the impact of size on growth varies among traits. Specifically, we demonstrate why for height growth the influence of: () leaf mass per unit leaf area is strong in small plants but weakens with size; () leaf nitrogen per unit leaf area does not change with size; () wood density is present across sizes; () height at maturation strengthens with size; and () seed mass decreases with size. Moreover, we show how traits moderate plant responses to light environment and also determine shade tolerance, supporting diverse empirical results.
植物物种在许多功能特征上存在差异，这些特征驱动着光合作用、生物量分配和组织周转率的差异。然而，目前尚不清楚这些特征如何——甚至是否——影响整个植物的生长，现有理论所预测的简单线性关系往往缺乏经验支持。在这里，我们通过扩展一个广泛使用的模型，将幼苗的生长速率与单个叶片特征联系起来，将其明确包括大小、光照环境以及五个突出特征（种子质量、成熟高度、单位叶面积的叶片质量、单位叶面积的叶片氮含量和木材密度）的影响，为理解不同功能特征对植物生长和耐荫性的影响提供了一个理论框架。基于生物量的生长和分配，该框架解释了为什么特征对生长速率和耐荫性的影响通常随植物大小而变化，以及为什么大小对生长的影响在特征之间存在差异。具体来说，我们展示了为什么对于高度生长：（）单位叶面积的叶片质量在小植株中影响较大，但随着大小的增加而减弱；（）单位叶面积的叶片氮含量不随大小而变化；（）木材密度在所有大小中都存在；（）成熟高度随大小而增加；（）种子质量随大小而减小。此外，我们还展示了特征如何调节植物对光照环境的反应，以及如何决定耐荫性，这与各种经验结果相支持。
