Extreme climate events and wet grasslands: plant traits for ecological resilience

Extreme climate events, including floods and droughts, represent disturbances that impact plant functioning, biodiversity and ecosystem processes. Wetlands can mediate climate change impacts through their multiple ecosystem services, and wet grasslands offer a fascinating wetland case because they are adapted to regular disturbance regimes typified by inundation, cutting and/or grazing. This review identifies key concepts for a better understanding of extreme climate impacts on wet grassland plant communities, focussing upon the use of functional traits for ecological resilience. It suggests that wet grasslands are underrepresented in extreme climate event experiments, despite some field studies that show floods have significant impacts upon community composition. Mechanisms for ecological stability and resilience are linked to functional diversity through plant traits, via niche complementarity or dominance. Facilitation may be important as climate stresses increase, while modified plant behaviour may promote recovery. However, plant community responses to extreme events are complex; the challenges for wet grassland researchers include: (i) identifying thresholds, tipping points and lag effects; (ii) monitoring key community components; (iii) using effective plant trait metrics; (iv) investigating beyond conservative norms; (v) combining multiple stressors and traits and (vi) extrapolating experimental results to field conditions.