Impact of CO2 rise on root, leaf and wood production: The future of tree C allocation

Globally, trees absorb CO2 in photosynthesis and allocate carbon (C) into leaves, wood, and roots where it can then remain within biomass and soil for decades. Therefore, C uptake by terrestrial vegetation is vital in the global C sink, absorbing around 1/3 of anthropogenic CO2 emissions. The question remains however, whether, and to what extent, forests will continue to contribute to the global C sink under elevated CO2 concentrations.
Research suggests that trees can carry out increased levels of photosynthesis under elevated CO2, but growth cannot increase indefinitely due to other limiting factors such as nutrient availability. Trees may be able to combat this to an extent by allocating this extra C belowground to obtain more nutrients.
This project aims to unravel the effect of CO2 fumigation on belowground processes of mature forests. Previous studies which have found greater C capture, notably by increasing root growth, have often been focussed on younger forests and plantations; so-called 'first generation' FACE (Free Air CO2 Enrichment) facilities, and do not necessarily produce an accurate representation of the impact of elevated CO2 on mature forests. This project will be carried out at the Birmingham Institute of Forestry Research (BIFoR), only the second running 'second generation' FACE facility in the world in collaboration with Forest Research and the Met Office.
Root production will be measured through the collection and vectorization of images using a minirhizotron camera, a cutting edge, non-destructive technique. This project will attempt to apply artificial intelligence (AI) to automate root image segmentation. Minirhizotrons will be used alongside more traditional soil cores. Data on root production will then be considered alongside other, previously collected C storage data, such as leaf area, to further understand where trees will allocate extra C under elevated CO2 and provide vital information to understand the future of the global C sink.