Impacts of savanna tree encroachment on livelihoods, water and carbon

Lead Supervisor: Prof Colin Osborne, Department of Animal and Plant Sciences
Co-Supervisor(s): Prof Frances Cleaver, Department of Geography; Dr Donatella Zona, Department of Animal and Plant Sciences

Project Description
Savannas cover half of Africa, supporting the livelihoods of hundreds of millions of people through grazing for livestock, groundwater recharge, and wood for charcoal. However, these goods and services are increasingly threatened by tree encroachment, which may eventually convert grassy savannas into thickets or forests. Tree encroachment is occurring on massive scales and at an accelerating rate. This multidisciplinary project aims to understand: i) the relationships between tree encroachment and the goods and services provided by savannas, with a particular focus on ecosystem water and carbon exchange; and ii) the contributions of savanna ecosystems to people’s livelihoods, with an emphasis on the ways in which local, regional and national institutions are involved in land management, and how people understand the encroachment problem. The PhD student will be trained in eddy covariance and participatory research methods, carrying out their fieldwork and working with stakeholders in the Eastern Cape of South Africa.

Savannas have a ground layer of grasses that supports grazing for livestock and wild animals, and a sparse layer of trees that enable groundwater recharge and provide wood for charcoal. These ecosystem goods and services are currently threatened at the continental scale by tree encroachment, thought to be caused by faster tree growth under rising atmospheric CO2. In this multi-disciplinary PhD, the student will examine what tree encroachment means for ecosystem function and the livelihoods of people in savannas. The project has two components:

  1. Ecosystem Science: How does encroachment impact ecosystem carbon sequestration, catchment water budget, and the production and quality of grass for livestock? Are there critical thresholds of tree cover that cause rapid gains or losses of carbon stocks, groundwater or grass? The student will directly measure carbon stocks and grass production along gradients of encroachment, and use eddy covariance towers to compare CO2 and H2O fluxes in encroached and unencroached landscapes.
  2. Social Science: How do the managers and users of land understand tree encroachment, and which local, district and national institutions are involved in managing the problem? Are there contradictions between the local, political and scientific understandings of tree encroachment and its consequences? The student will build an understanding of land-use in encroached savannas by using participatory methods to map the resource-use, livelihoods and institutional landscape of land governance.

The PhD research will use field sites in the Eastern Cape of South Africa as case studies, collaborating especially with Professor Brad Ripley from Rhodes University.

Subject Areas: Ecology & Conservation; Development Studies; Climatology & Climate Change; Environmental Science

Funding notes
This four-year studentship will be fully funded at Home/EU or international rates. Support for travel and consumables (RTSG) will also be made available at standard rate of £2,627 per annum, with an additional one-off allowance of £1,000 for a computer in the first year.  Students will receive an annual stipend of £17,336.  Applications should be received and complete by Monday 26th March 2018.

What to include in the application
Your application for this studentship should be accompanied by a CV and a 200 word supporting statement. Your statement should outline your aspirations and motivation for studying in the Grantham Centre for Sustainable Futures. You should also outline any relevant experience and interests that you have in sustainability issues.

Please select ‘Standard PhD’ and the department of this project’s lead supervisor. Fill in the title of your desired project and the name(s) of the supervisors. The starting date of the PhD will be the start of the next academic year – 1 Oct 2018. The ‘Funding stage’ on the form will be ‘project studentship’.