Towards a trait‐based ecology of wetland vegetation

Functional traits mechanistically capture plant responses to environmental gradients as well as plant effects on ecosystem functioning. Yet most trait‐based theory stems from terrestrial systems and extension to other habitats can provide new insights. Wetlands differ from terrestrial systems in conditions (e.g. soil water saturation, anoxia, pH extremes), plant adaptations (e.g. aerenchyma, clonality, ubiquity of bryophytes) and important processes (e.g. denitrification, peat accumulation, methane emission). Wetland plant adaptations and trait (co‐)variation can be situated along major plant trait trade‐off axes (e.g. the resource economics spectrum), but soil saturation represents a complex stress gradient beyond a simple extension of commonly studied water availability gradients. Traits that affect ecosystem functioning overlap with patterns in terrestrial systems. But wetland‐specific traits that mediate plant effects on soil redox conditions, microbial communities and on water flow, as well as trait spectra of mosses, vary among wetland types. Synthesis. With increasing availability of quantitative plant traits a trait‐based ecology of wetlands is emerging, with the potential to advance process‐based understanding and prediction. We provide an interactive cause‐and‐effect framework that may guide research efforts to disentangle the multiple interacting processes involved in scaling from environmental conditions to ecosystem functioning via plant communities.