Understanding the carbon budget of nursery-grown trees, shrubs and herbaceous plants, for cultivated green spaces

Gardens provide important environmental and socio-cultural benefits to people, both to individuals managing their own gardens and on a larger scale across cities and towns. A key ecosystem service benefit supported by gardens is the sequestration and storage of carbon in plants and soils, with typically greater carbon stocks per unit area than the agricultural landscape surrounding urban areas. However, residential urban greenspaces are multi-faceted; involving a large range of stakeholders and a diverse variety of plant species and cultivars, making them difficult to manage to maximise these benefits. The competing pressure for land coupled with the UK government commitment to build more than 1 million new homes this parliament offers both the opportunity and the necessity to maximise the ecosystem services delivered by plants and soils in new residential greenspace. Providing evidence-based decision making to nurseries and landscaping on the most environmentally suitable species and cultivars, both now and under future climate change, offers the opportunity to shape the resilience of residential green spaces in urban areas at scale. However, there is uncertainty in both the carbon sequestration rates of nursery grown trees, shrubs and herbaceous plants at a species and cultivar level, and how that is translated into carbon storage both above and below ground. This uncertainty limits the ability of developers and gardeners to make informed choices about vegetation structure and species / cultivar selection in gardens.

This PhD will address the following objectives:

1. Demonstrate the Ecosystem Service potential (carbon sequestration and storage) of nursery-grown trees, shrubs and herbaceous plants, for real-world application in cultivated green spaces (e.g. gardens, housing and other developments) by quantifying photosynthetic rates and the above/below ground biomass of a range of species / cultivars within those plant groups.

2. Refine UK-based allometric relationships (e.g. root/shoot ratios) for typical nursery-grown plant groups.

3. Quantify differences in plant growth rates according to species and planting location using traditional destructive techniques and novel remote sensing-based approaches (e.g. Terrestrial laser scanning).

4. Create understanding of the importance of different species / cultivars (per plant group) for carbon storage and sequestration potential to sign-post gardeners and developers towards informed decision making.

This exciting project will give the PhD student the opportunity to work with the RHS, the UKs largest gardening charity and with an industrial partner, Greenwood Plants. The PhD candidate will be based at the University of Sheffield in the School of Biosciences, and will benefit from fieldwork with co-supervisors at RHS and Greenwood Plants. The student will be supervised by Dr Jill Edmondson (urban ecology and soil and carbon budgeting), Dr Holly Croft (remote sensing and plant physiology), Dr Mark Gush (Head of Environmental Horticulture at the RHS) and Melanie Asker (Managing Director of Greenwood Plants). The student will develop a range of skills including carbon budgeting of soils and vegetation, plant physiology and remote sensing.

Students from diverse backgrounds are encouraged to apply.