Within-species patterns challenge our understanding of the Leaf Economics Spectrum

The utility of plant functional traits for predictive ecology relies on our ability to interpret trait variation across multiple taxonomic and ecological scales. Using extensive datasets of trait variation within species, across species, and across communities, we analyzed whether and at what scales ‘leaf economics spectrum’ (LES) traits show predicted trait-trait covariation. We found that most variation in LES traits is often, but not universally, at high taxonomic levels (between families, between genera in a family). However, we found that trait covariation shows distinct taxonomic scale-dependence, with some trait correlations showing opposite signs within versus across species. LES traits responded independently to environmental gradients within species, with few shared environmental responses across traits or across scales. We conclude that, at small taxonomic scales, plasticity may obscure or reverse the broad evolutionary linkages between leaf traits, meaning that variation in LES traits cannot always be interpreted as differences in resource use strategy.