Project overview: Trees are increasingly being incorporated into agricultural landscapes to provide shade, improve soils, support biodiversity, store carbon and protect farms from climate extremes. However, trees also use water, and the consequences of tree planting for water availability depend strongly on tree characteristics, root and canopy systems, soil conditions, climate and the spatial configuration of trees within farming systems. This PhD (3.5 years) will investigate the mechanisms driving water use by trees in tree-based agricultural systems (TIFs) across contrasting environmental and agroclimatic contexts.
The research forms part of the ERC-funded TIF-CER project awarded to Prof Pfeifer: From Forests to Fields to Sustainable Rural Landscapes: A Multiscale Framework for Quantifying Biodiversity and Climate Interrelationships. TIF-CER is establishing an international network of field plots across contrasting agroclimatic zones in the UK, Italy, Philippines, Tanzania, Chile and Tunisia. The project will work with local partners and research teams.
Tree morphology will be quantified alongside microclimate, sap flow and soil-water measurements. The project will examine how these change with tree age, density, spatial configuration, soil conditions and agroclimatic context. This will help establish whether tree traits can be used to predict water use without requiring intensive measurements for every individual tree. Field observations will be combined with process-based modelling to investigate mechanisms that cannot be measured directly across large spatial and temporal scales.
Research questions: The PhD will address questions about tree–water interactions, including:
How does tree morphology and canopy structure influence water use? How do tree traits interact with tree density, configuration, soil and climate to determine water availability? How does water use vary between young and mature tree-based systems and between different types of tree-based agriculture? What proportion of water used by trees is derived from different soil depths and water sources? Can aboveground tree morphology be used to predict belowground water use and root-zone water dynamics? Can mechanistic models be used to predict how different tree-based farming systems influence water stress and water availability under future climates?
Field research: A major component of the PhD will involve intensive in-situ field measurements in selected sites of the TIF-CER field network and integration of data from across the field network. Measurements will capture water dynamics at multiple points within the soil-plant-atmosphere continuum. The project will use advanced environmental sensing technologies, sap-flow sensors to quantify individual tree water use, radiation and microclimate measurements. The project will also use stable isotope analysis (δ18O and δ2H) of rainfall, soil water and plant water to investigate where trees obtain their water from and how water sources change between wet and dry periods. Mechanistic models will be calibrated using field measurements The modelling will allow the candidate to explore scenarios that cannot be tested directly in the field, including changes in tree density, tree configuration and climate.
The PhD will contribute to a broader objective of TIF-CER: understanding how processes operating at the scale of individual trees translate into outcomes at the scale of farms and landscapes. The PhD will be embedded within an international research programme involving researchers in ecology, hydrology, conservation science, landscape ecology, soil science, emote sensing, genomics and environmental modelling. The candidate will have opportunities to contribute to international fieldwork and collaborate with researchers and stakeholders in TIF-CER study countries. The aim is to explore how findings can inform practical landscape management and tree-based restoration. This will provide experience of conducting environmental research across contrasting climatic, ecological and socio-economic contexts.
Training: The project provides training across several complementary areas:
- Field ecology and environmental monitoring
- Deployment of soil-moisture, sap-flow and microclimate sensors
- Understanding transpiration, soil-water dynamics, and tree water-use efficiency
- Stable isotope ecology Using δ18O and δ2H to identify sources of plant water.
- Statistical modelling of high-frequency environmental and physiological data.
- Remote sensing and spatial analysis
Candidate profile
We are looking for an enthusiastic candidate with a strong interest in plant-water relations, ecology, environmental science, hydrology, agricultural systems or a related discipline.
Essential criteria:
- a good degree in a relevant subject
- experience in experimental and field-based research
- experience in quantitative analysis and data interpretation using R
- willingness to undertake fieldwork in contrasting environmental conditions.
Experience in one or more of the following would be advantageous:
- environmental sensor deployment;
- stable isotope analysis;
- GIS or remote sensing;
- process-based environmental modelling.
You do not need to have experience in all of these areas. The project is deliberately interdisciplinary and training will be provided. The results will contribute to understanding how tree-based farming systems can be designed to support climate adaptation, agricultural production and sustainable water management.