Photic barriers in a warming world: the crucial role of photoperiod in shaping plant responses to climate change

Martina Tarascio ¹, Anna Cazzavillan ², Lisa Brancaleoni ², Renato Gerdol ², Maurizio Cutini ³, Thomas Abeli ¹

University of Pavia ¹, University of Ferrara ², Roma Tre University ³

Photoperiod (the daily duration of light and dark) is a key seasonal signal for plants, influencing physiological and phenological processes such as photosynthetic efficiency, bud burst, flowering, growth cessation, senescence and dormancy. Photoperiod will not change as the climate warms, leading to potential asynchrony in these functionally paired cues. Global mean air temperature increases of up to 4.5 °C are predicted by the year 2100, but even greater warming is projected for middle to high northern latitudes. Despite its importance, there is a lack of extensive literature regarding the role of photoperiod on the response of plant species and communities to the ongoing climate crisis. In this study we reviewed 85 studies addressing the combined effects of photoperiod and climate change on plant distribution, plant traits, plant phenology, plant physiology, evolutionary potential and ecological interactions. Recently, climate change attributable to human influence has been recognized as among the most important contemporary forces driving species’ distribution ranges. Our review highlights that plant communities are shifting their ranges northward or to higher elevations in response to climate warming, but photoperiodicity and other non-climatic factors may limit the success of these migrations, as species with highly photoperiod-dependent responses may encounter "photic" barriers to their movement. Species adapted to different latitudes show variable responses to photoperiod, influencing their migration potential. Different photoperiodic sensitivity of species within a community may alter the competitive ability across species and latitudes in a warmer climate. For example, short-day species that may reach high latitudes through long-distance dispersal events may survive in the new environment but may be unable to flower and reproduce. Changes in flowering time might have negative implications for the survival of these species, as a mismatch between time of flowering and pollinator activity might also occur. Moreover, species that rely on shorter days in autumn for the induction of senescence, might not benefit from improved climatic conditions and a longer growing season at mid latitude. Changes in phenological traits are among the most obvious responses to global warming, yet photoperiod and temperature influence these events in complex ways, with strong variations based on species and latitude. A clear example is represented by the time of bud burst, which represents a compromise between a spring frost avoidance and a sufficiently long growing season. Understanding the role of both photoperiodic and temperature cues on different physiological/phenological traits is therefore crucial to understand how different plant communities and species will be affected by climate change in the near future. This review highlights the importance of disentangling these factors to predict and mitigate the impacts on ecosystems and species as well as underlying the many implications that these have on assisted and natural migrations, the competitive potential of invasive species, agriculture, prediction models, ecosystemic services and biogeochemical cycles.

Main author career stage: Postdoc / Fellow

Contribution type: Talk

First choice session: 2. Ecology

Second choice session: 3. Biodiversity and global change