Project highlights

  • Saltmarsh ecosystem responses to combined eCO2 x eT treatments. 
  • Field research based at SMARTX experiment at the Smithsonian, USA 
  • Laboratory research based at Wolfson Glasshouses (UoB) 

Overview

Saltmarshes are among the most carbon dense ecosystems worldwide with high primary productivity and burial rates1. As wetland soils are typically saturated, a large portion of the CO2 taken up by plants through photosynthesis and stored in belowground biomass is buried for centuries. Yet, the blue carbon stored in saltmarsh soils may be offset by the potent greenhouse gases (GHG), CH4 and N2O, which are produced and consumed during soil biogeochemical processing and have the potential to increase under global climate change2. Because most of the biogeochemistry that controls GHG emissions occurs belowground, it is critical to understand root production, mortality and exudation to forecast the future carbon sink potential of saltmarshes.  

Despite the importance of saltmarshes for carbon sequestration, understanding of how their ecosystem functioning will be altered due to global change is not fully understood. There is the potential for both increased primary productivity and carbon burial, and increased soil decomposition and greenhouse gas emissions3. In the Salt Marsh Accretion Response to Temperature eXperiment (SMARTX) at SERC, temperature and atmospheric CO2 have been manipulated in-situ for 8 years. Initial results show that elevated temperature (eT) and elevated atmospheric CO2 (eCO2) treatments alter annual biomass allocation, CH4 emissions and C sequestration4,5. These trends are strongly driven by seasonal patterns of root production, mortality and exudation. To fully understand the belowground mechanisms that control ecosystem-level responses to climate change it is critical to quantify root dynamics and relate them to soil biogeochemical processes and GHGs. The proposed approach will use in-situ experimental treatments and controlled laboratory manipulation of individual drivers. This will enable understanding of synergistic versus antagonistic effects of salt marsh resilience to global change. Thus, the findings from this project will improve understanding of broader saltmarsh responses to climate change, and the resilience of their ecosystem services, which is valuable for global efforts to comprehend and mitigate the effects of climate change. This is critical given recent work to include blue carbon in the UK’s national greenhouse gas inventory requiring better understanding of current and future blue carbon storage capacity and may inform restoration and management strategies6,7. 

Two images showing installation of minirhizotron tubes for information. Someone holding a minirhizotron tube, standing on a metal boardwalk over a saltmarsh. Someone installing a minirhizotron tube into the saltmarsh soil, inside an experimental plot with heating lamps. (Please note this is greater than the character limit because it is for two photos and not one).

Figure 1. Installation of the minirhizotron tubes to image root production at the Global Change Research Wetland. Elevated temperature treatments are achieved with heating lamps and belowground warming cables, while elevated atmospheric CO2 is manipulated using open-top chambers. (Picture of SERC, 2021) 

CENTA Flagship

This is a CENTA Flagship Project

Case funding

This project is suitable for CASE funding

Host

University of Birmingham

Theme

  • Climate and Environmental Sustainability
  • Organisms and Ecosystems

Supervisors

Project investigator

Co-investigators

How to apply

Methodology

The project combines state-of-the art experimental facilities at the University of Birmingham (Wolfson Glasshouses) with those at the Smithsonian Environmental Research Center (SMARTX experiment) to investigate effects of elevated CO2 and temperature on saltmarsh functioning, representing global change scenarios.  

Minirhizotron technology deployed at SMARTX will be used to study root dynamics. The minirhizotron images will be analysed using a machine learning protocol developed by BiFoR. This will be coupled with mesocosm-scale exposures of saltmarsh plant species to eCO2 and eT to determine the effect of these key climatic drivers on root exudate production and composition, C and N cycling and associated fluxes of CH4 and N2O. Novel 15N and 13C stable isotope tracers in controlled manipulation experiments in the University of Birmingham’s Wolfson Glasshouses will be used to enable responses of key biogeochemical processes to be determined and assessment of potential implications for future saltmarsh functioning. 

Training and skills

DRs will be awarded CENTA Training Credits (CTCs) for participation in CENTA-provided and ‘free choice’ external training. One CTC can be earned per 3 hours training, and DRs must accrue 100 CTCs across the three and a half years of their PhD.  

In addition, during the course of the PhD, the student will receive several key trainings by the supervisory team:  

  • Quantification of root dynamics with minirhizotron technology coupled with machine learning. 
  • Greenhouse gas measurement, data analysis and accounting under scenarios of global changes 
  • Using novel stable isotope tracers to determine biogeochemical reaction rates. 
  • Project management including managing a transnational research project. 
  • Data management and statistical analysis following FAIR principles. 
  • Scientific writing and dissemination 

Partners and collaboration

Smithsonian Environmental Research Center (SERC) hosts one of the project’s experimental sites where minirhizotron technology was developed and deployed in 2021 by Dr. Arnaud. SERC will provide co-supervision, access to their facilities, equipment and consumables and will host the student during year 1. Dr. Arnaud co-developed the project and provides technical support on the minirhizotrons as well as expertise on root dynamics in coastal wetlands under global change scenarios. Dr. Clilverd at UKCEH is developing UK national GHG inventories to include Blue Carbon and will link with the DR to input project results. 

Further details

 For any enquiries related to this project please contact Dr. Sophie Comer-Warner: [email protected] , Prof. Sami Ullah: [email protected] .

 To apply to this project:  

  • You must include a CV with the names of at least two referees (preferably three) who can comment on your academic abilities.  
  • Please submit your application and complete the host institution application process via: https://sits.bham.ac.uk/lpages/LES068.htm.   Please select the PhD Geography and Environmental Science (CENTA) 2025/26 Apply Now button. The CENTA Studentship Application Form 2025 and CV can be uploaded to the Application Information section of the online form.  Please quote CENTA 2025-B6 when completing the application form.  

 Applications must be submitted by 23:59 GMT on Wednesday 8th January 2025.   

Possible timeline

Year 1

Literature review, minirhizotron campaign to monitor root dynamics, field experiments to determine greenhouse gas fluxes and soil biogeochemical processes.

Year 2

Controlled manipulation experiments (derived from in-situ results) in the Wolfson glasshouses to determine greenhouse gas fluxes and soil biogeochemical processes, data analysis, manuscript preparation.

Year 3

Data analysis, manuscript preparation, results dissemination and conferences.

Further reading

Journal:  

  1. McLeod, E., et al., 2011. A blueprint for blue carbon: Toward an improved understanding of the role of vegetated coastal habitats in sequestering CO2. Frontiers in Ecology and the Environment. 9(10), 552-560 
  1. Tobias, C. and Neubauer, S., 2019. Salt Marsh Biogeochemistry: An Overview in Coastal Wetlands: An Integrated Ecosystem Approach. 539-596 
  1. FitzGerald, D. M. and Hughes, Z., 2019. Marsh processes and their response to climate change and sea-level rise. Annu. Rev. Earth Planet. Sci. 47, 481–517 
  1. Noyce, G.L. and Megonigal, J.P. Biogeochemical and plant trait mechanisms drive enhanced methane emissions in response to whole-ecosystem warming. Biogeosciences. 18, 2449-2463. 
  1. Noyce, G.L. et al. (2023) ‘Oxygen priming induced by elevated CO2 reduces carbon accumulation and methane emissions in coastal wetlands’, Nature Geoscience, 16(1), pp. 63–68 
  1. Burden, A., Clilverd, H. 2021. Moving towards inclusion of coastal wetlands in the UK LULUCF inventory – Rapid assessment of activity data availability. Report to the Department for Business, Energy & Industrial Strategy (BEIS). UK Centre for Ecology & Hydrology, Bangor. 61pp 
  1. UK Government. 2022. Net Zero Strategy: Build Back Greener. Net Zero Strategy: Build Back Greener – GOV.UK (www.gov.uk)