Drought impacts on Amazon rainforest soil: carbon, structure and ecology

Summary

This PhD offers a unique opportunity to study the effects of long-term drought on soil carbon storage and soil biology in Amazonian rainforest. Please read all the information at https://www.ed.ac.uk/geosciences/study/degrees/research-degrees/phd-projects/physical-sciences?item=1483 to find out more and how to apply. The current deadline is 20 February 2023. We wish to appoint a candidate asap to join us Spring 2023.

Project background

You will join a world-class international research team, perform fieldwork in the Amazon, and will develop an exceptional set of skills and networks to help you take the next step forward in your career. Besides UK-based supervisors, there will be international supervision from Prof Beto Quesada, Amazon Research Institute, Manaus, Brazil (INPA) and Prof Antonio da Costa, Federal University of Pará, Brazil.

Tropical rainforests exchange more carbon dioxide with the atmosphere than any other land biome. This partly reflects their geographic size, but also high metabolic rates driven by warmer temperatures and generally high moisture availability. Changes in the loss or gain of carbon from tropical forest ecosystems can substantially affect the global carbon balance (1), but accelerating and persistent climate change threatens to cause these forests to act as much smaller absorbers of carbon dioxide than in previous decades (2).  In Amazônia an increasing frequency of climate extremes, particularly drought and warming, are key drivers of these changes, but the effects remain poorly understood, limiting our ability to predict change and related risk (3, 4). 

 This is particularly true of the soil, an understudied but critical component of tropical forest ecosystems. Tropical soils contain one third of the carbon stored in soils globally (5). This carbon is vulnerable to climate change, especially over the long term. Our short-term evidence suggests that these large carbon stores are very vulnerable to climate change (6), and are at risk of releasing substantial amounts into the atmosphere. But there is very little understanding of the long-term impacts of climate change on the large stores of carbon in these soils, and on their structure and ecology. Our team leads the world’s only long-term (>10-year) ecosystem-scale drought experiment in tropical forest. Based in Amazônia this experiment offers an entirely unique scientific opportunity to advance our understanding of long-term climate change effects on tropical forests, at ecosystem scale. The PhD will bring together a supervisory network from across the UK and Brazil, providing exceptional field, laboratory, modelling and networking opportunities for the successful applicant, all in a rapidly emerging and high-impact field.

Research questions

A core underpinning question for the PhD will focus on the effects of decadal-scale (20 years) drought on the stock of soil carbon. However, the student is expected to build outwards from this, considering the influence of changing structure and function in the soil and vegetation during extended drought. Some alterations to the forest have been very large during the experiment, for example the loss of substantial biomass through increased tree mortality (7,8); whilst others have been more subtle and include alterations to the microbial community, and potentially to the use of nutrients (9).

Methodology

The PhD student will gain expertise in soil structural, chemical and biological analysis, and will have the opportunity to consider links between soil biogeochemistry, microbial ecology and root properties. A range of data analysis skills will be developed, including the learning of leading-edge statistical methods, and the potential to integrate findings with relevant modelling groups. The student will also gain substantial experience in the use of scientific equipment, collaboration, project management, working in a foreign language and culture, and working as part of a team. 

Requirements

1. Masters degree desirable, and/or strong undergraduate in relevant discipline (ecology, plant science, ecophysiology, soil science, ecosystem science)
2. Experience of field work, desirable in tropical countries, remote locations.
3. Language skills, or aptitude/desire to learn (Brazilian Portuguese)
4. Experience of succeeding working in team environments as well as individually.