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Cambridge NERC Doctoral Training Partnerships

Graduate Research Opportunities

Lead supervisor: Andrew D. Friend, Geography

Co-supervisor: Ulf Buntgen, Geography

Brief summary: 
This project will investigate the mechanisms responsible for the formation of tree rings in seasonal climates, with implications for our understanding of carbon sequestration, tree ecology, and dendroclimatology.
Importance of the area of research concerned: 
Future climate change will be largely determined by the rate of increase in atmospheric CO2. The current rate of increase is strongly moderated by the activity of carbon sinks on land and in the oceans. On land, the major sink is the formation of wood, and it has been estimated that the equivalent of ca. 18% of emitted fossil fuel carbon is sequestered in wood each year. Despite the importance of this sink, our understanding of its drivers and controls is poor. Improvements in such knowledge would allow us to represent growth processes directly in global vegetation models, interpret tree ring anatomy in terms of climate conditions, and support efforts to improve wood quality and carbon sequestration.
Project summary : 
We have developed a computer model which simulates the daily production and maturation of cells in response to signals controlling the rate and duration of different stages. It successfully reproduces the observed anatomical features of tree rings in seasonal climates, such as the sequence of low density earlywood followed by high density latewood (which gives rise to the characteristic tree-ring pattern of light and dark wood) and the sensitivity of ring width and latewood density to temperature (which are used to estimate previous climates in dendroclimatology). This model therefore provides the theoretical basis to study the impacts of environmental factors on tree growth, and the implications of different species-specific physiologies on carbon sequestration and responses to climate change. This project will test, extend, and apply this model.
What will the student do?: 
The student will explore the behaviour of the wood formation model under different conditions utilising a range of datasets. These will include ring width and latewood density from various locations around the world and data obtained by experiments in collaboration with the University of Cambridge Sainsbury Laboratory and the Umeå Plant Science Centre, Sweden. These comparisons will suggest model improvements that might be required, and species-specific parameterisations. These will be developed and the model extended to a range of species and anatomies. The model will be used to simulate historical trends in tree growth and carbon sequestration, with results compared to tree datasets and other measures of carbon uptake, such as from flux towers and atmospheric records. It will also be used to predict future carbon sequestration given scenarios of atmospheric CO2 and climate change. The outcome of the project will be a breakthrough in our ability approach to simulating tree growth, from a mechanistic perspective, with major implications for our understanding of the global carbon cycle, plant growth, and the interpretation of tree ring data.
References - references should provide further reading about the project: 
Friend, A.D., Eckes-Shephard, A.H. and Tupker, Q., 2022. Wood structure explained by complex spatial source-sink interactions. Nature Communications, doi:10.1038/s41467-022-35451-7.
A.D. Friend, Eckes-Shephard, A., Fonti, P., Rademacher, T.T., Rathgeber, C., Richardson, A.D. and Turton, R.H., 2019. On the need to consider wood formation processes in global vegetation models and a suggested approach. Annals of Forest Science, doi:10.1007/s13595-019-0819-x
S. Fatichi, Leuzinger S, Körner C. 2014. Moving beyond photosynthesis: from carbon source to sink-driven vegetation modeling. New Phytologist 201: 1086– 1095.
You can find out about applying for this project on the Department of Geography page.