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Background and Aims While trait-based approaches have provided critical insights into general plant functioning, we lack a comprehensive quantitative view on plant strategies in flooded conditions. Plants adapted to flooded conditions have specific traits (e.g. root porosity, low root/shoot ratio and shoot elongation) to cope with the environmental stressors including anoxic sediments, and the subsequent presence of phytotoxic compounds. In flooded habitats, plants also respond to potential nutrient and light limitations, e.g. through the expression of leaf economics traits and size-related traits, respectively. However, we do not know whether and how these trait dimensions are connected. Methods Based on a trait dataset compiled on 131 plant species from 141 studies in flooded habitats, we quantitatively analysed how flooding-induced traits are positioned in relation to the other two dominant trait dimensions: leaf economics traits and size-related traits. We evaluated how these key trait components are expressed along wetness gradients, across habitat types and among plant life forms. Key Results We found that flooding-induced traits constitute a trait dimension independent from leaf economics traits and size-related traits, indicating that there is no generic trade-off associated with flooding adaptations. Moreover, individual flooding-induced traits themselves are to a large extent decoupled from each other. These results suggest that adaptation to stressful environments, such as flooding, can be stressor specific without generic adverse effects on plant functioning (e.g. causing trade-offs on leaf economics traits). Conclusions The trait expression across multiple dimensions promotes plant adaptations and coexistence across multifaceted flooded environments. The decoupled trait dimensions, as related to different environmental drivers, also explain why ecosystem functioning (including, for example, methane emissions) are species and habitat specific. Thus, our results provide a backbone for applying trait-based approaches in wetland ecology by considering flooding-induced traits as an independent trait dimension. [ABSTRACT FROM AUTHOR]

Wetland plants live in habitats which are distinguished from terrestrial ecosystems by their unique characteristics including anoxic conditions, frequent flooding and submergence. To understand how/why they deviate from terrestrial plants, a comprehensive quantitative knowledge of trait selection in wetlands is needed. We built a global database of wetland plant functional traits which includes >8000 observations of >1200 species from >200 references (containing both published and unpublished sources), encompassing leaf economics traits, eco-physiological adaptation traits and also associated environmental data from a variety of wetland habitats around the world. Our database is unique in aiming only at plants living in wetland habitats, and it has not been included in the TRY database yet.Based on our database, we analysed the principal driving factors for wetland adaptation traits. We showed that different drivers affect adaptation traits differently. This suggests that seemingly similar wetland stresses (anoxia, flooding) across a variety of wetland habitats still select for a distinct set of wetland adaptation traits. We also noticed that some of the wetland adaptation traits were statistically decoupled from leaf economics spectrum (LES) traits, which suggests that wetland adaptation traits may not be constrained by the habitat resources/nutrient limitation. This allows wetland plants to survive in complex wetland ecosystems under varied hydrological regimes and fertility status. We also found trade-offs between some of the adaptation traits and LES traits, which suggests that plants need to optimize the allocation of resources between survival and growth for certain environmental stresses. The fact that no clear leading dimension was detected for wetland adaption traits emphasizes the complex character of wetland ecosystems.Our database will provide the backbone for quantitatively understanding the wetland plant species' adaptation strategy, distribution and their link to ecosystem functioning such as the carbon and nitrogen cycles for future studies at a global scale. [ABSTRACT FROM AUTHOR]

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. [Display omitted] • Freshwater plants have been underexamined in the context of functional biogeography. • Global mapping efforts focusing on their form and function are needed. • This will help advance our understanding of freshwater plant unique adaptations. • Such an exercise will be accomplished by the MAP Project (www.lifeinmud.com/map). • We are recruiting collaborators from around the world, starting in late 2021. [ABSTRACT FROM AUTHOR]