Overview

Project Highlights:

  • Field research based at world leading BIFoR FACE experiment facility, enabling in situ study of high CO2 world, as part of multidisciplinary research community
  • Unique opportunity to establish mechanisms of leaf litter decomposition and how these may change under eCO2
  • Potential within the project to shape the research objectives during year 3 in response to data and candidate’s interests.

 

Overview

The Birmingham Institute of Forest Research Free Air Carbon Enrichment Facility (BIFoR FACE) is an outdoor experiment studying the impact of elevated carbon dioxide (eCO2) on an established deciduous forest ecosystem through several multi-disciplinary research projects. This PhD opportunity focuses on changes in leaf chemistry, leaf litter decomposition and microbial nutrient cycling under eCO2.

Changes in atmospheric CO2 are likely to influence the quantity and quality of organic matter in plant biomass and soil carbon pools with implications for the reactivity and recycling of carbon and other nutrients during decomposition. Leaf litter decomposition is a major pathway in the soil carbon cycle and understanding its response to eCO2 is crucial to determine the potential for soils to act as carbon sink, or carbon source.

This project will compare mature forest canopy leaves and leaf litter from both ambient and eCO2 atmosphere at the BIFoR FACE Facility, to establish how the balance of nutrients in plant biomass changes under eCO2. Identifying this change in leaf quality is crucial to understanding leaf litter reactivity, which will further impact decomposition, microbial processing and nutrient release in forest soil.

The mechanisms of decomposition and soil biogeochemistry are complex. By examining the decomposition of eCO2-grown leaves versus controls in both ambient and eCO2 atmosphere, this project also aims to untangle the potentially rapid response to eCO2 of soil microbes on decomposition and nutrient return, from the indirect effect of leaf quality on organic matter reactivity.

Biogeochemical analyses of leaves, leaf litter, soil and soil water in ambient and eCO2 atmosphere at BIFoR FACE, will establish differences in leaf biomass nutrient balance, from canopy to soil. Isotopic analyses of carbon and nitrogen will trace these nutrients from leaf, to litter, to soil, further describing the efficiency of nutrient uptake and return in a high carbon world.

 

Methodology

Field research will include sampling canopy leaf, leaf litter, soil and soil-waters from the BIFoR FACE Facility, as well as conducting leaf litter decomposition experiments at the site. Field research may also be complemented by laboratory incubation experiments, depending on early research outcomes, and the interest of the candidate. Laboratory preparation and analysis of BIFoR FACE samples will take place in University of Birmingham geochemical laboratories and GEMS (isotope) Facility and will include elemental composition of soils, canopy leaf and litter by chemical extraction and analysis, as well as C and N isotopic analysis of leaf and soil material by mass spectrometry.

Training and Skills

Full training will be given in field sampling of canopy leaf biomass, litter, soils and soil-waters, with particular focus on the constraints of field experiment design, maintenance, collaboration and safety as part of the BIFoR FACE Facility. In-house training will be given in general laboratory safety, skills, calibration and analysis, including ion-chromatography, UV-vis spectrophotometry, ICP-OES, SKALAR auto-analyser, TOC analyser, and sample preparation for mass spectrometry.

This project forms an integral part the of BIFoR FACE research community. The candidate will attend weekly multi-disciplinary meetings and research talks with collaborators ranging from volunteers to professors, fostering shared learning and development.

Timeline

Year 1: Leaf composition and decomposition - field sampling and laboratory chemical analysis of canopy leaves, leaf litter and organic soil horizons to determine changes in leaf quality in response to eCO2; litter decomposition experiments to establish the relative importance of leaf litter quality and reactivity, or soil biogeochemistry, as drivers of change under eCO2.

Year 2: Tracing the isotopic signal - C and N isotopic analysis of canopy leaves, selected litter samples, and soil. This will determine the fate of ‘new’ CO2 in fumigated arrays and quantify the transfer of additional carbon through living leaves, litter and soil, as well as identifying changes in nitrogen demand and processing. This will build on chemical leaf quality and reactivity data from year 1.

Year 3: Dependent on results from years 1 and 2, and the candidate’s interests, the final year of data collection can: continue the time series of canopy leaf and leaf litter quality, reactivity and decomposition under eCO2; continue the C and N isotopic composition of plant biomass and soil; or, expand on the connection between leaf chemistry and biodegradation in laboratory experiments.

Partners and collaboration (including CASE)

This project will benefit from the extraordinary collaborative efforts of scientists across the world, who have contributed to designing and building the BIFoR FACE Facility and continue world leading multi-disciplinary research projects there. As well as technical support, BIFoR FACE offers support and learning opportunities from peers, in a vibrant research community.

This project also has the support of collaborative partnerships in leaf litter research with Prof David Roberts, University of Manchester, Dr Alan Jones, Earthwatch; and has synergy with ongoing PhD projects at BIFoR FACE focusing on other aspects of the leaf cycle.

 

Further Details

Please contact Dr Rebecca Bartlett (r.bartlett@bham.ac.uk) for further information.