- Ecophysiology research in an area of rapidly increasing societal importance
- Experimental work and field data collection
- Join an expanding team of urban tree and ecology research
The importance of urban vegetation, or ‘green infrastructure’, is now well recognised for the multitude of ecological, societal, health and climate benefits it brings to the urban environment and residents. Trees are a key component of green infrastructure, and therefore understanding the ecological and physiological characteristics of urban trees in a changing environment is essential, particularly because urban environments differ from non-urban environments, where most of our knowledge on tree ecophysiology has been derived. Urban soil properties differ, water infiltration varies with surface cover and planting approach, and species composition is influenced by cultural and economic factors, and it is unsure whether the species that have been used historically are appropriate for a warming and drying future.
Urban trees are at the nexus of climate change feedbacks. Urban environments are ahead of non-urban environments with respect to global change: temperatures tend to be higher in urban environments due to the urban heat island (UHI) effect, due to heat absorption and release by the built infrastructure. At the same time, atmospheric CO2 concentrations also tend to be higher in urban environments, with implications for stomatal responses and water use, as plants may reduce stomatal conductance and their water loss while maintaining similar carbon assimilation under the elevated CO2. In this way, urban trees can provide us insight into how non-urban trees will respond to future climate conditions. Urban trees also have an important role in mitigating climate change impacts of urban environments through their carbon sequestration and cooling properties. Cooling comes from shading, which depends on canopy extent and configuration, and transpiration, which depends on stomatal responses and soil water access. Therefore, the water use efficiency response to elevated CO2 may reduce the cooling effectiveness of some species.
This project will investigate the physiology and water use efficiency of urban tree species within the context of climate change feedbacks and future-proofing climate-smart cities. It will take advantage of a range of infrastructure at the Open University as part of an expanding urban tree and ecology group.
Figure 1: A majestic London plane tree in an urban park providing shade, habitat and amenity value.
HostThe Open University
- Climate and Environmental Sustainability
- Organisms and Ecosystems
Depending on the interests of the student, a range of approaches are available. Controlled outdoor experiments on large potted trees will be conducted using our ‘treecosm’ system where soil water content can be manipulated, and water use monitored, to investigate the effects of different water availability. Different tree species will be investigated, including common urban tree species and native and introduced species. In situ urban woodland measurements on campus include sapflow across different species, microclimate conditions and canopy light transmittance. Physiological responses can be investigated using leaf gas exchange and fluorescence, hyperspectral reflectance and solar induced fluorescence, and pigment content analysis. Integrated water use efficiency responses can be investigated using stable carbon isotope analysis. Species distribution datasets are available through the OU-run Treezilla citizen science platform (the largest UK dataset of urban trees).
Training and skills
Students will be awarded CENTA2 Training Credits (CTCs) for participation in CENTA2-provided and ‘free choice’ external training. One CTC equates to 1⁄2 day session and students must accrue 100 CTCs across the three years of their PhD.
The student will receive training plant ecophysiological measurements, field spectroscopy, and hyperspectral data cube analysis. You will also be supported in the development of your skills in experimental planning and project management, including liaising with external organisations where applicable (such as local authorities). Those with an interest in citizen science will have the chance to develop this through Treezilla and other platforms at the OU. A rich and varied training programme is available to OU PG students which includes sessions on academic writing, research design and data management, career development communicating your research, as well as opportunities to get involved in public engagement, media and remote digital teaching.
We invite applications from students with a strong background in plant, ecosystem or forest/tree ecology or physiology, an interest in urban ecosystems and global change processes and an enthusiasm for field work and independent research. A clean driving licence for accessing field sites is desirable.
The successful student will join well-established teams researching environmental and ecosystem processes and a vibrant postgraduate community at the Open University.
If you wish to apply to the project, applications should include:
- A CENTA application form, downloadable from: CENTA application
- A CV with the names of at least two referees (preferably three and who can comment on your academic abilities)
- An Open University application form, downloadable from: Home OU application form (if you are resident in the UK) or an Overseas OU application form (if you are an international applicant). Please quote CENTA23_OU10 when completing the application form.
- Please send your completed application to: [email protected]
Applications to be received by the end of the day on Wednesday 11th January 2023.
Literature review, experimental set-up, first season of measurements.
Data analysis and second season of measurements. Local conference presentation.
Data analysis and writing up. International conference presentation.
The student will be encouraged to join national and international network programmes such as COST Actions and develop their own networks through the course the PhD.
Kagotani, Y., Fujino, K., Kazama, T. et al. (2013) Leaf carbon isotope ratio and water use efficiency of urban roadside trees in summer in Kyoto city. Ecological Research 28, pp. 725–734. doi: 10.1007/s11284-013-1056-7.
Rahman, M.A., Armson, D., Ennos, A.R. (2015) A comparison of the growth and cooling effectiveness of five commonly planted urban tree species. Urban Ecosystems 18, pp. 371–389. doi: 10.1007/s11252-014-0407-7.
Roy S., Byrne J., Pickering C. (2012) A systematic quantitative review of urban tree benefits, costs, and assessment methods across cities in different climatic zones. Urban Forestry & Urban Greening 11(4), pp. 351-363. doi: 10.1016/j.ufug.2012.06.006.
Most of the data collection is outdoors, minimising infection risk, or involves desk-based data analysis that can be done in low occupancy offices or at home. Where lab work is involved, a low dependence on time-critical analysis (samples can be stored frozen or dried) means this can be flexibly incorporated into lab booking schedules.