Species-level responses to environmental change depend on the collective responses of their constituent populations and the degree to which these populations are specialized to local conditions. Thermal tolerance limits in ferns remain poorly understood, and even less is known about these limits at the population level. Being the second most diverse group of vascular land plants, this leaves a large gap in our understanding of how contemporary plant species will respond to elevated temperatures that will be occurring in the future.

In a recent Editor’s Choice article published in AoBP, Chambers & Emery focus on thermal tolerance of the fern species Vittaria appalachiana, endemic to rockshelters of the Appalachian Mountains of North America. Populations of V. appalachiana occupy rockshelters from northern Alabama to south-western New York, spanning a total of 9° in latitude, and while rockshelters can buffer these populations from fluctuations in temperature, the latitudinal distribution exposes populations to different average thermal conditions. In this study, Chambers & Emery tested the hypothesis that previously detected population differentiation in a fern species is due to differentiation in thermal performance curves among populations. Plants from six populations spanning the species’ geographic range were collected and exposed to 10 temperature treatments. Plant survival, lifespan and the change in photosynthetic area were analysed as a function of temperature, source population and their interaction. Results indicated that thermal limits across all populations are relatively conserved and correspond highly to those experienced in the field, leaving little room for adaptation and tolerance in light of elevated temperatures in the future. Management to conserve this species, and others that are dispersal limited, asexual and physiologically sensitive to climate, will likely require assisted migration techniques, which would facilitate the colonisation of suitable habitat that becomes available with climate change.

Researcher highlight

Sally Chambers obtained a PhD in Ecology and Evolutionary Biology from Purdue University under the direction of Dr. Nancy Emery in 2014. She then worked for three years as a postdoctoral researcher at the University of Florida in the lab of Dr. Emily Sessa. In 2017, Sally was hired as a Research Botanist at Marie Selby Botanical Gardens in Sarasota, Florida, where she currently works.

Sally is interested in plant species’ distribution patterns and responses to global climate change. She utilizes a variety of tools to address her research questions, including modern molecular and modelling techniques, and classic field and manipulative experiments. Most of her research focuses on the enigmatic, and often under studied, vascular plants, the ferns.