Data from: Are leaf functional traits “invariant” with plant size, and what is “invariance” anyway?

Studies of size-related plant traits have established a suite of mathematical functions describing whole plant investment and allocation. In parallel, studies of plant “economic spectra” have measured the scaling and variance composition of traits related to the major dimensions of both structure and function. Here we explore the intersection of these two broad areas by exploring the notion that many leaf economic traits are invariant with species differences in adult plant size. Invariant traits are those that do not change with plant size and are invoked as a key simplifying assumption of prominent models that purport to explain the scaling of plant size and metabolism. Unfortunately, leaf trait invariance is neither well defined nor understood, and has never been critically evaluated. Using a global plant trait dataset, we evaluated whether nine key traits can be considered as effectively invariant as a function of the maximum height of plant species, within and across plant growth forms, and within and across broad taxonomic groups. We also examine the influence of habitat, biome and global spatial scales on the size-relative variance in plant functional traits. We suggest that while invariance is an intuitive concept, an objective statistical definition is elusive. Expanding on ideas drawn from the study of life history invariants, we propose five criteria to identify traits that are effectively invariant, depending on the research question. We show that all studied “leaf economic spectrum” (LES) traits approach invariance within and between herbaceous and woody plant groups; angiosperms and gymnosperms; and within most biome and habitat types. Individual leaf area, however, shows a modest increase with plant size, and there are significant shifts in the average LES trait values at a given plant maximum height, among the plant growth forms and taxonomic groups. Our results demonstrate that generally, LES traits show little interspecific variation with maximum plant height, which provides some support for attempts to model plants with “average” leaf properties. Our work also highlights the need for a better understanding of the drivers of leaf size variation within and across individuals, functional groups, clades, biomes and habitats.

Usage Notes
Price et al Data for DryadLeaf functional trait data, plant and leaf size, habitat and biome classifications for 540 plant species.

关于植物大小相关性状的研究，已确立了一系列数学函数，用以描述整个植株的投资与分配。与此同时，关于植物“经济光谱”的研究，已测量了与结构及功能主要维度相关的性状的尺度和变异性组成。在本研究中，我们通过探讨许多叶片经济性状与成年植株大小物种差异无关的观念，来探索这两个广泛领域的交汇点。不变性状是指不随植株大小变化的性状，这些性状被视为众多旨在解释植株大小和代谢尺度的显著模型的关键简化假设。遗憾的是，叶片性状的不变性既没有得到明确的定义，也未得到充分的理解，且从未被批判性地评估。利用全球植物性状数据集，我们评估了九个关键性状能否被视为与植物物种最大高度相关的有效不变性状，无论是在植物生长形态内部和之间，还是在广泛分类群内部和之间。我们还考察了生境、生物群落和全球空间尺度对植物功能性状大小相关变异性的影响。我们认为，虽然不变性是一个直观的概念，但客观的统计定义却难以捉摸。在借鉴生命史不变性研究中的观点的基础上，我们提出了五个标准，以识别有效不变性状，这取决于研究问题。我们发现，所有研究的“叶片经济光谱”（LES）性状在草本和木本植物组之间以及之内，在被子植物和裸子植物之间，以及在大多数生物群落和生境类型中，都趋向于不变性。然而，单个叶片面积随植株大小的增加而适度增加，而在给定的植株最大高度上，不同植物生长形态和分类群之间的平均LES性状值发生了显著变化。我们的结果表明，一般而言，LES性状在最大植株高度方面显示出较小的种间变异性，这为用“平均”叶片性质来模拟植物的努力提供了一定的支持。我们的研究还突出了更好地理解个体、功能群、分支、生物群落和生境中叶片大小变异驱动因素的需求。

使用说明
Price 等人 Dryad 数据
叶片功能性状数据、植株和叶片大小、生境和生物群落分类数据，适用于 540 种植物。