Biological stoichiometry of plant production: metabolism, scaling and ecological response to global change

Summary Biological stoichiometry theory considers the balance of multiple chemical elements in living systems, whereas metabolic scaling theory considers how size affects metabolic properties from cells to ecosystems. We review recent developments integrating biological stoichiometry and metabolic scaling theories in the context of plant ecology and global change. Although vascular plants exhibit wide variation in foliar carbon : nitrogen : phosphorus ratios, they exhibit a higher degree of ‘stoichiometric homeostasis’ than previously appreciated. Thus, terrestrial carbon : nitrogen : phosphorus stoichiometry will reflect the effects of adjustment to local growth conditions as well as species’ replacements. Plant stoichiometry exhibits size scaling, as foliar nutrient concentration decreases with increasing plant size, especially for phosphorus. Thus, small plants have lower nitrogen : phosphorus ratios. Furthermore, foliar nutrient concentration is reflected in other tissues (root, reproductive, support), permitting the development of empirical models of production that scale from tissue to whole‐plant levels. Plant stoichiometry exhibits large‐scale macroecological patterns, including stronger latitudinal trends and environmental correlations for phosphorus concentration (relative to nitrogen) and a positive correlation between nutrient concentrations and geographic range size. Given this emerging knowledge of how plant nutrients respond to environmental variables and are connected to size, the effects of global change factors (such as carbon dioxide, temperature, nitrogen deposition) can be better understood. Contents Summary 593 I. Introduction 594 II. Variation in plant C : N : ratios: how much and what are the sources? 595 III. The growth rate hypothesis in terrestrial plants and the scaling of whole‐plant N : P stoichiometry and production 597 IV. Scaling from tissues to whole plants 599 V. Applications: large‐scale patterns and processes associated with plant stoichiometry 601 VI. Global change and plants: a stoichiometric scaling perspective 603 VII. Synthesis and summary 604 Acknowledgements 605 References 605