Overview

Project Highlights:

  • State-of-the-science research at a world-leading facility.
  • A question of fundamental importance for climate change and sustainable land-use.
  • A vigorously interdisciplinary research environment closely connected to private, public and charity sectors world-wide.

The response of forest ecosystems to elevated CO2 is one of the major uncertainties in understanding the impact of increased CO2 emissions1. A key feedback system exists between terrestrial ecosystems and atmospheric CO2: increasing CO2 may stimulate photosynthesis, in turn increasing ecosystem carbon sink capacity and therefore slowing the rate of CO2 increase. This carbon-climate feedback is crucial to future climate projections, but still is the most uncertain. Temperate forests are particularly important biomes for controlling this feedback. 

The fundamental photosynthetic behaviour is understood, as is much of the behaviour of saplings in laboratory media and plantations of immature trees on arable soil. The behaviour of mature trees in forest soil systems is not well established, because the experiments required are of a magnitude very seldom seen in terrestrial ecology (Figure 1).

Free-Air Carbon Dioxide Enrichment (FACE) facilities are the most direct and robust platform to study the effects of elevated CO2 on woodland/forest ecosystems2. Experiments currently underway include EucFACE3 and AmazonFACE4 on subtropical and tropical forests.

The Birmingham Institute of Forest Research (BIFoR) FACE facility is unique in the Northern Hemisphere, and aligns with EucFACE and AmazonFACE to form a global ‘machine’ investigating forest response to elevated CO2. Set in temperate broadleaf oak-with-hazel woodland (Mill Haft, Staffordshire, UK5), BIFoR-FACE tests hypotheses derived from lab-based and mesocosm studies of forest carbon cycling in a fully-open and complete real-world ecosystem.

Conventional ecological theory suggests that mature woodlands maintain a balanced cycle of carbon, nitrogen, phosphorus and other nutrients. Analyses suggest that contemporary woodland ecosystems are taking up CO2, hence reducing climate change impacts of fossil-fuel burning. Do mature forests have the capacity to increase carbon uptake under elevated CO2, or do other factors limit carbon sequestration? If the system stores more carbon, where will this be allocated (crown, stem, roots or soil)? How do factors like water use and nutrient availability affect carbon allocation? Will the morphology of the trees change?

The aim of this project is to investigate carbon allocation responses of a mature woodland to elevated CO2, with the goal of linking structural responses to underlying function and ecosystem processes. It will use measurements of structure, physiology and growth, and place these results in a global context.

Objectives:

  • To develop quantitative comparisons of canopy structure between control and treatment plots using in-situ and remote sensing techniques, to determine the fast (i.e. first year) and medium-term changes in stand structure and tree morphology;
  • To identify relationships between carbon allocation responses and water-use and nutrient availability;
  • To assess the generality of results through comparison with prior and ongoing (EucFACE, AmazonFACE) studies.
An aerial view of the FACE rings at Mill Haft. Inset: a laser-scan image of the trees for above-ground carbon assesement.

Methodology

This PhD is part of a major FACE programme investigating the response of mature forest ecosystems to elevated CO2. The FACE facility comprises 9 woodland patches: 3 receiving ambient air plus 150 ppmv of CO2; 3 receiving ambient air using the same infrastructure as those patches receiving extra CO2; and 3 undisturbed patches. Instruments and sampling regimes are already in place for the measurements below; the student will be able to make rapid progress by immersion in a rapidly expanding research team supported by a team of 4 facility technicians.

Aboveground carbon allocation. Stem dynamics will be monitored by web-enabled dendrometers and laser-scanning of stand structure; shoot growth and leaf morphology will be measured in-situ; leaf, flower, and propagule production will be quantified by direct sampling, by leaf-area index (LAI) and leaf mass per unit area (LMA) measurements, and accessing litter collected in complementary projects. Large woody debris will be quantified using structure-from-motion photogrammetry.

A particular focus will be on differential responses between standard oaks and coppice and sub-dominant hazel, sycamore, hawthorn, and holly.

Baseline samples and data are available from years (2015-2016) prior to CO2 fumigation and will form part of the analysis.Corroborative data on nutrients, trophic interactions, and climatology will be available through the consolidated BIFoR-FACE database.

Training and Skills

The Doctoral Researcher will receive key training from the University of Birmingham in project planning and undertaking field work, including climbing to access the canopy. They will receive hands-on training in a wide range of advanced field and laboratory analysis techniques, associated spatial geostatistical analysis and visualisation and data interpretation. The Doctoral Researcher will be supported to present their work at international conferences and publish their findings in high-impact journals. There will be the opportunity to attend selected modules from MSc courses taught within the School.

CENTA students are required to complete 45 days training throughout their PhD including a 10 day placement. In the first year, students will be trained as a single cohort on environmental science, research methods and core skills. Throughout the PhD, training will progress from core skills sets to master classes specific to CENTA research themes. 

Timeline

Year 1: Field site induction, literature review, instrument and CENTA training. 1st summer measurement campaign.

Year 2: Maintenance of field kit. 2nd summer summer measurement campaign and start on first manuscript. Present at local conference.

Year 3: Data compilation and analysis, international conference attendance, thesis and publication preparation.

Partners and collaboration (including CASE)

The Supervisory team: Prof Rob MacKenzie leads the Birmingham Institute of Forest Research; he is an atmospheric scientist who has worked extensively on plant-atmosphere interactions. Dr Kadmiel Maseyk is an ecophysiologist interested in how plant function affects ecosystem carbon and water biogeochemistry. Dr. Rick Thomas overseas the experimental teams at the woodland, maintains the canopy CO2 flux measurements, and is an expert in novel sensor design and use, particualry in relation to drone technology.

Laser-scanning of Mill Haft is done in collaboration with Forest Research (FR), the research agency of the Forestry Commission. We will seek to engage FR as co-supervisory (CASE) partners.

[If selected we will offer Earthwatch (Dr Alan Jones) a non-academic supervisory role to connect the project with their dendrometer studies at BIFoR FACE and their citizen science activities.]

Further Details

The applicant should have a strong background in a relevant discipline such as Biogeochemistry, Ecology, Plant Biology, Environmental Engineering or Environmental Science and an enthusiasm for field work and independent research. A clean drivers license is desirable.