One teaspoon at a time – revealing the role of microbes in peatland carbon cycling

Katy Ross

In order to understand greenhouse gas emissions from ecosystems we need to know about microbes. They are the primary divers of terrestrial to atmospheric carbon cycling, with up to 101 microbial cells in each gram of soil2. In peatlands, the limited microbial decomposition of organic matter facilitates their incredible power to store carbon. However, we have little mechanistic understanding of the role of microbial species in breaking down organic matter, and particularly, how these processes will be influenced by a changing climate.

Peatland microbes fall into two main groups aerobic and anaerobic. The aerobic group live in the dry oxygenated layers of peat close to the surface. They have surplus oxygen so are very active in the decomposition of organic matter. Up to 90% of carbon, entering a peatland is lost in this zone as carbon dioxide by the respiration of microrganisms3. In the anaerobic zone, decomposition is much slower, limited by the lack of oxygen and poorer quality peat that has already been utilised by aerobic bacteria. This is where methane is produced and when considered on a global scale it is wetlands including peatlands, where the largest source of methane emissions emerge from4.

A changing climate will directly influence these groups and their role in carbon cycling. As temperatures rise and drought events become increasingly frequent, the aerobic zone is likely to become larger, exposing more peat to oxygen and facilitating the rapid breakdown of more organic matter and the release of CO2.

But what are the effects of this changing climate on microbial carbon cycling in Falkland peat and how might we mitigate these effects through land management?

Over the past few months Katy has carried out a sampling campaign to try and answer these questions. She’s been travelling to sites across East Falkland to take samples of peat for microbial analysis. From each site samples have been collected from the surface, where bacteria will be living in close association with vegetation all the way to the anoxic (no oxygen) zones at the base of the peat.

By visiting sites with different grazing strategies she hopes to determine how land management may influence community composition and therefore carbon cycling. As the water table levels have been well described at these sites, it may also be possible to explore the influence of the anaerobic and aerobic zones on microbial communities and the role of grazing in determining the extent of these zones. By linking these findings to greenhouse gas flux measurements that have been made concurrently we can see how microbial communities are influencing respiration and the production of CO2 and start to make predictions about how emissions will vary with changing climates.
Image left:  A teaspoon of soil holds billions of bacterial cells. This sample will soon be sequenced along with hundreds of others at the Natural History Museum in London allowing us to get a better understanding of the microbial communities present in Falkland peat.

The samples (image right) have now been packaged up and are now on their journey to the UK in the freezers aboard the RSS Sir David Attenborough. Katy will join them in October at the Natural History Museum to begin revealing the identity of each of those millions of cells.

If you want to hear more about the project or get involved contact or follow along with her research on Twitter at @girl_in_a_bog

Collaborators on the project include the Centre for Ecology and Hydrology, the University of Leicester and the Natural History Museum. Katy's PhD supervisors include Dr Steffi Carter, Prof Chris Evans, Prof Sue Page, Dr Anne Jungblut, Dr Arnoud Boom and Dr Ross Morrison. And a huge thank you to local sponsors Georgia Seafoods and the British Antarctic Survey for allowing shipment of samples.


  1. Sandhu, H. S., Gupta, V. V., & Wratten, S. D. (2010). Evaluating the economic and social impact of soil microbes. Soil microbiology and sustainable crop production, 399-417.
  2. Rosselló-Mora, R. and Amann, R. (2001) ‘The species concept for prokaryotes’, FEMS Microbiology Reviews, 25(1), pp. 39–67. doi: 10.1111/j.1574-6976.2001.tb00571.x
  3. Rydin, H., Jeglum, J. and Bennett, K. (2013) The biology of peatlands, 2e. Available at: &sig=-93F1tbrhCdLTnyOaBlN3qgzEsI (Accessed: 18 May 2022).
  4. Green, S. M. (2013) ‘Ebullition of methane from rice paddies: The importance of furthering understanding’, Plant and Soil. Springer, pp. 31–34. doi: 10.1007/s11104-013-1790-1.
  5. Some text adapted from the thesis and probation review of Katy Ross
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