Does the leaf economic spectrum hold within local species pools across varying environmental conditions

Summary Understanding patterns of trait variation across environmental variability is necessary for development of ecological predictions. The leaf economic spectrum (LES) has demonstrated global trade-offs in leaf traits, but it is unclear whether such patterns are robust in local communities exposed to varying environments. We conducted separate greenhouse experiments to examine the effects of varying water-table depth and nitrogen availability on leaf-level trait values among a suite of co-occurring wetland species. We then assessed the effects of species-specific trait value responses on relationships predicted by LES and whether species responded similarly to variations in water-table depth and nitrogen availability. We found that both water-table depth and nitrogen availability had significant species by treatment interactions for specific leaf area, leaf nitrogen and photosynthetic rates, indicating species-specific responses to environmental variability. The responses of individual traits to different treatment levels were relatively consistent across species, but multivariate responses were more variable. We found that apart from significant relationships between specific leaf area and photosynthetic rate under some treatments, there was little support for the relationships predicted by the LES. These results suggest that, before trait-based ecology will be able to make progress towards using plant traits to predict responses of communities and ecosystems to changes in environmental drivers, considerable attention needs to be paid to the processes that control intraspecific trait variation.