Project Highlights:

  • Opportunity to investigate how trees will use water in the future using unique forest experimental facility
  • Opportunity to use a wide variety of field and analytical tools (including isotopes) cutting across forestry and water science disciplines
  • Wide scope of international collaboration and research opportunities

The earth’s atmosphere is changing, with increasing CO2 concentrations changing the way the planet looks through its impact on vegetation. The earth is getting greener in some places (refs), and trees all over the earth appear to be changing the way they use water (refs). These changes will impact forests and water resources globally, but until now we have not had a way to test how trees will actually respond to higher CO2 in the future. This project will help fill this important gap by using a globally unique experimental facility that is artificially enhancing the CO2 concentrations of an old growth oak forest in central UK (BIFoR FACE).

In terms of changes to tree water use, this may decrease because stomata will open less frequently, or alternatively the canopy leaf area may increase (‘CO2 fertilization effect’), creating higher overall transpiration rates. These questions over “how much” are important, but there is also the critical, and as yet overlooked, question of “which” water is being taken up and used by trees. This project will utilise δ2H and δ18O stable isotopes as a method to trace the water being used by trees over the growing season at the BIFoR CO2 enrichment experiment (FACE) to gain the first mechanistic insights into which water the forest of the future will use.

This work will have important implications that will directly inform how we think about forests and catchments of the future. Forest regeneration efforts are expanding globally and are widely recognised as providing many beneficial ecosystem services, but how resilient these forests of the future will be with changing water and climate dynamics is highly uncertain. This project will provide critical insights into how they might respond to water stress, how we might think about their planting and management. Finally, this work will also inform catchment water management by examining whether how the results might apply at larger scales, specifically how the water being used by trees in turn changes the water available for soils and rivers and hence the supply of water resources downstream. These forest and water resource implications will be worked on directly with project partners and collaborators in the Environment Agency, as well as other partners in the forestry sector, allowing the student to also translate research into policy practice.

A possible future forest water – carbon scenario that this project would help test, disentangling what water trees are using, and how this might change in the future. This project will test these dynamics using stable water isotopes as a tracer, at the globally unique experimental BIFoR FACE experiment in the UK midlands (inset photo).


The student will use water and vegetation monitoring and sampling techniques to determine changes in water use and ecophysiology at the BIFOR experimental forest facility in collaboration with other researchers. Water samples from rain, soil, and vegetation will be analysed for stable water isotopes over the growing season at the facility. Importantly, the student will be able to compare which water is used by trees at different times under controlled (ambient CO2) and elevated CO2 conditions, providing a robust measure of changing water use and source patters due to climate change. This may also include the use of gas chromatography so that processes rates can be examined.

Training and Skills

This project will offer unique training at the interface of physical and biological sciences, including ecophysiology, forestry, biogeochemical cycling, and water transport between soils, trees, and the atmosphere. In addition, it will provide unique training in geochemical tracers such as stable isotopes of water (δ2H and δ18O), and how these can be used to infer both water source and transport dynamics. The project will involve extensive training in field, laboratory, and statistical / mathematical data analysis. The student will also work within a large experimental forestry site (BIFoR), gaining exposure to large scale experimental work, and forestry research. Finally, the student will work closely with partners, especially the Environment Agency, to learn how research can be translated into policy practice.


Year 1: Establish monitoring and sampling setup and program for plant-water dynamics and stable isotopes.

Year 2: Begin data analysis and work closely with international collaborators to investigate the water use dynamics being revealed. Continue field monitoring and sampling.

Year 3: Possibility for overseas travel to work with international collaborators on finalising results. Work closely with project partners in the UK (Environment Agency) to summarise policy implications and ways forward for the future of forest and catchment management

Partners and collaboration (including CASE)

The Environment Agency will be a CASE partner in this project, with co-supervision of the project from Dr Glenn Watts. The project also offers the opportunity for extensive international collaboration and learning, especially from the University of Saskatchewan with co-supervisor Jeff McDonnell, and the large water security research groups working there. In addition, the student will have the opportunity to work with Prof Melanie Leng, who runs the stable isotope component of National Environmental Isotope Facility, based at the British Geological Survey (BGS) near Nottingham.

Further Details

This project has been selected as a CENTA Flagship project. This is based on the projects fulfilment of specific characteristics e.g., NERC CASE support, collaboration with our CENTA high-level end-users, diversity of the supervisory team, career development of the supervisory team, collaboration with one of our Research Centre Partners (BGS, CEH, NCEO, NCAS), or a potential applicant co-development of the project.

For more information on the project, please do not hesitate to contact Josh Larsen j.larsen@bham.ac.uk

More information on the Birmingham CO2 enrichment experiment can be found here:


More information on the National Environment Isotope Facility at BGS can be found here: