Data from: Functional traits as predictors of vital rates across the life cycle of tropical trees

The ‘functional traits’ of species have been heralded as promising predictors for species’ demographic rates and life history. Multiple studies have linked plant species’ demographic rates to commonly measured traits. However, predictive power is usually low – raising questions about the practical usefulness of traits – and analyses have been limited to size-independent univariate approaches restricted to a particular life stage. Here we directly evaluated the predictive power of multiple traits simultaneously across the entire life cycle of 136 tropical tree species from central Panama. Using a model-averaging approach, we related wood density, seed mass, leaf mass per area and adult stature (maximum diameter) to onset of reproduction, seed production, seedling establishment, and growth and survival at seedling, sapling and adult stages. Three of the four traits analysed here (wood density, seed mass and adult stature) typically explained 20–60% of interspecific variation at a given vital rate and life stage. There were strong shifts in the importance of different traits throughout the life cycle of trees, with seed mass and adult stature being most important early in life, and wood density becoming most important after establishment. Every trait had opposing effects on different vital rates or at different life stages; for example, seed mass was associated with higher seedling establishment and lower initial survival, wood density with higher survival and lower growth, and adult stature with decreased juvenile but increased adult growth and survival. Forest dynamics are driven by the combined effects of all demographic processes across the full life cycle. Application of a multitrait and full-life cycle approach revealed the full role of key traits, and illuminated how trait effects on demography change through the life cycle. The effects of traits on one life stage or vital rate were sometimes offset by opposing effects at another stage, revealing the danger of drawing broad conclusions about functional trait–demography relationships from analysis of a single life stage or vital rate. Robust ecological and evolutionary conclusions about the roles of functional traits rely on an understanding of the relationships of traits to vital rates across all life stages.

物种的“功能性状（functional traits）”长期以来被视为预测物种种群动态速率与生活史的极具潜力的预测因子。已有多项研究将植物物种种群动态速率与常规测定的功能性状建立关联。然而，这类关联的预测能力通常较低——这引发了关于性状实际应用价值的质疑——且现有分析多局限于特定生活史阶段下、与体型无关的单变量方法。本研究针对巴拿马中部136种热带树种，在其完整生活史周期内同时评估了多性状的预测能力。本研究采用模型平均法，将木材密度、种子质量、比叶面积（leaf mass per area）以及成年株高（最大直径）与繁殖起始、种子生产、幼苗建成，以及幼苗、幼树和成树阶段的生长与存活建立关联。本研究分析的4个性状中，有3个（木材密度、种子质量与成年株高）通常能在特定生命速率与生活史阶段解释20%至60%的种间变异。在树木完整生活史中，不同性状的重要性会发生显著转变：种子质量与成年株重在生命早期占据主导地位，而木材密度则在幼苗建成后成为关键影响因子。每个性状对不同的种群动态速率或不同生活史阶段均存在相反的作用效应：例如，种子质量与更高的幼苗建成率相关，却与更低的初始存活率相关；木材密度与更高的存活率相关，却与更低的生长速率相关；而成年株高则会降低幼体的生长与存活，但提升成体的生长与存活。森林动态由完整生活史周期内所有种群动态过程的综合效应所驱动。采用多性状与完整生活史周期的分析方法，能够揭示关键性状的完整作用机制，并阐明性状对种群动态的效应如何随生活史进程发生变化。性状对某一生活史阶段或种群动态速率的效应，有时会被另一阶段的相反效应所抵消，这也揭示了仅通过单一生活史阶段或种群动态速率的分析，就得出功能性状与种群动态间关联的普遍性结论所存在的风险。要得出关于功能性状作用机制的可靠生态学与进化学结论，必须先明确性状在所有生活史阶段与种群动态速率之间的关联。