Towards linking freshwater plants and ecosystems via functional biogeography

Functional biogeography has advanced the field of functional ecology into a more spatially-predictive science. However, freshwater plants are still underrepresented in these trait-based advancements. Here, we argue that there is a need for developing a functional biogeographical framework for freshwater plants and initiate global mapping efforts focusing on the form and function of freshwater plants. Specific attention should be given to (1) the placement of freshwater plants in the global plant trait space and show how this placement links to global trait-environment relationships; (2) the theoretical framework for major structural trait-trait correlations based on the physical constraints in aquatic ecosystems; (3) the evolutionary and environmental drivers underlying the global distribution of inter- and intra-specific variation in different life forms; and (4) the level of equilibrium between spatial and temporal trait-environment relationships in freshwater plants. By putting freshwater plants in the context of these spatial aspects, we could advance our understanding of freshwater plant adaptations and responses to environmental gradients, and thereby facilitate predicting the consequences of global changes for freshwater ecosystem functions and services.