Grasslands maintained with frequent fire promote cold‐tolerant species

Question: In temperate grasslands and savannas that were historically maintained by frequent, low-intensity fires, disturbance by fire may promote community resistance to winter climate change by favouring slow-growing, resource-conservative species that may also be more cold-tolerant. The lack of functional trait data for measuring cold tolerance, however, has prevented testing this idea. We ask, are slower growing, resource-conservative species more cold-tolerant than fast-growing species, and are plant responses to fire frequency and cold tolerance related?. Location: Prairies and savannas of south-central Wisconsin, USA. Methods: We measured leaf cold tolerance for 120 plant species from prairies and savannas and compared cold tolerance to fire affinity as well as other functional traits describing plant strategies. Results: As predicted, resource-conservative species are more cold-tolerant than fast-growing species in temperate grasslands and savannas. Cold tolerance is also associated with disturbance regime such that species found in frequently burned sites are more cold-tolerant. Conclusions: The ability to predict the degree of susceptibility of species and communities to winter climate change and extreme climate events, such as freezing, will provide insight into the conservation and management practices to promote species persistence into the future. Under climate change, communities composed of more stress-tolerant species may be more likely to persist. Our results demonstrate that cold-tolerant species are more common in temperate grasslands and savannas managed with frequent, low-intensity fire that simulate historic disturbance regimes. Identifying and maintaining ecosystems composed of stress-tolerant species may play a key role in preserving natural communities under environmental uncertainty.