Grant: Discovery Grants Program - Individual

Atmospheric carbon dioxide (CO2), air temperature, growing season length, and soil nutrient contents have all increased drastically in the Arctic under global change, and induced major shifts in tundra ecosystem functioning. Comparatively, the direction of change in radiation at the ground surface, with reports indicating both an increase in diffuse radiation and a decrease in direct and total radiation since 2000, as well as the related responses of tundra plant species, are largely unknown. Whereas early work has suggested that increasing diffuse radiation can increase tundra productivity, it remains to be understood how leaf-level photosynthesis and tundra productivity respond to variation in radiation over a long term and at larger scale, and how radiation modifies optimal strategies of carbon capture in plants that are already exposed to increases in other plant resources (CO2, nutrient, temperature). This project will aim at investigating the influence of direct, diffuse, and total radiation on the functioning of Arctic plant ecosystems, through two main objectives: (i) assessing the extent of interspecific variation in leaf-level photosynthesis in relation to direct and diffuse radiation; (ii) studying adaptation and acclimation of tundra ecosystem functioning to changes in radiation intensity and diffusivity. For the first objective, we will investigate tundra plant traits related to leaf-level photosynthesis, chemistry, and anatomy, in 5-7 species over a long latitudinal gradient, from alpine tundra (Chic-Choc mountains QC) to sub-arctic (Umiujaq, QC), low-arctic (Iqaluit, NU), and high-arctic tundra (Bylot Island, NU). Along this gradient, we will notably cover the south and north edges of the distribution ranges of two erect shrub species, Salix richardsonii and Betula glandulosa, which are involved in the greening of the Arctic. For the second objective, we will set up a long-term manipulative field experiment in Umiujaq (Nunavik), where plants will be subjected to four treatments of incoming radiation: ambient radiation (control), increased and decreased direct radiation, and increased diffuse radiation. This work will specifically focus on erect shrub species (Betula, Alnus, Salix spp.) over a 10 year-period, and will be based on a close partnership with the Umiujaq community. Central to this program, seven highly qualified personnel will be trained to functional plant biogeography and open-science framework, and get competencies in multiple high-skilled techniques in gas and radiation monitoring. Most importantly, they will benefit from the long-term collaboration with a First Nation community that will ensure community-based monitoring and knowledge co-production.