Feeling the heat: understanding the impact of high temperatures on future tree functioning under elevated CO2

About the project

About the Project Photosynthesis is a process vital to plant growth and is highly sensitive to temperature (Crous et al. 2022). When CO 2 is high, plants close their leaf pores (stomata) to save water - but this traps heat and makes increases leaf temperatures (Fauset et al. 2019). Despite increasing air temperatures, very few studies have tested the impact of elevated CO 2 on leaf temperatures of mature trees with implications for carbon capture and hence creating a major gap in our climate models (Oliver et al 2025). Using the unique BIFoR-FACE site ( BIFoR FACE - University of Birmingham ), our previous research has shown that elevated CO 2 increases the canopy temperatures of the dominant mature oak ( Quercus robur ) trees, especially under heatwave conditions (Hagan Brown et al. 2025). This has significant implications for future tree functioning and carbon sequestration. How will the co-dominant and understory species leaf temperature respond to elevated CO 2 and does the shading from oaks allow these trees to sustain carbon capture under higher atmospheric temperatures? This project will test whether co-dominant and understory tree species, namely sycamore ( Acer pseudoplatanus ) and hazel ( Corylus avellana ) may sustain their carbon capture and resist significant leaf warming due to the shading effect of the dominant oak trees at BIFoR-FACE. The species selection is particularly important as sycamore trees have been observed to be vulnerable to hot droughts; this project will elucidate why. The project will use multiple approaches to investigate canopy temperatures, understand the mechanisms of variation in canopy temperature between dominant and sub-canopy species, and assess the impact of warming on mature tree leaf function. The studentship will address the following objectives: Objective 1: Assess species-specific differences in leaf and canopy temperatures of oak, sycamore and hazel. Objective 2: Determine the drivers of interspecific variation in canopy temperature due to canopy structure, exposure and functional traits. Objective 3: Assess the impacts of leaf warming on sycamore and hazel physiology using branch heating experiments. Objective 4: Use the data from objectives 1 to 3 to determine impacts for leaf warming and shading on photosynthesis and carbon capture to accurately simulate forest responses to climate extremes under elevated CO 2 Timeline: Year 1: Monitor leaf temperatures of multiple species at BIFoR-FACE using multiple methods including drone surveys to relate crown structure to canopy temperature. Year 2: Perform leaf warming experiments on Acer pseudoplatanus and Corylus avellana. Year 3: Perform simulations of leaf gas exchange of UK temperate forest species under climate change scenarios. Preparation of papers and thesis. For this project, we are looking for an enthusiastic student with a relevant degree (e.g. environmental science, ecology, biology, geography or related subjects). Experience of fieldwork and statistical analysis is beneficial. Some work at height may be required. This PhD is fully funded for UK students by RenEco ( RenEco News - Supporting BIFoR's forest CO2 experiment ). The project will be supervised by Dr Sophie Fauset and Dr Alice Gauthey. Please contact Dr Sophie Fauset ( s.fauset@bham.ac.uk ) if you have any questions or to discuss the project. The scholarship will begin from January 2027. To apply, please make a formal application via the University of Birmingham ( Apply for an advertised PhD - University of Birmingham ).

Research areas