In spring 2024, ECT awarded University of York PhD candidate Nina Overtoom a small grant towards repair and replacement of key monitoring equipment at the Cors Fochno long-term climate change manipulation experiment in mid-Wales. This was co-funded by our grants scheme partner Ramble Worldwide Outdoor Trust. We invited Nina to write about her 2024 fieldwork experience at the site, implementing the important summer drought simulation.
Flash floods, tropical storms, heatwaves, droughts, and wildfires — 2024 was a stark reminder of how climate change amplifies extreme events (Ripple et al., 2024). Maintaining carbon storage in natural systems like oceans, vegetation, and soils is critical to mitigating climate change. Northern peatlands, while covering just ~3% of the Earth’s surface (Xu et al., 2018), store around 550 GtC (Yu et al., 2010) making them vital carbon reservoirs. However, extended summer droughts threaten their stability by lowering water tables, introducing oxygen into waterlogged soils, and accelerating microbial decomposition of organic matter into CO₂ (Laine et al., 2019).
Despite their importance, most climate change experiments on peatlands are short-term and focus on either warming or drought (Le Geay et al., 2024). To address this gap, a long-term climate change experiment was established at Cors Fochno, a near-natural lowland raised bog in Wales, in 2010. Now in its 14th year, this experiment offers unique insights into the combined effects of warming and drought on peatlands. In 2024, I had the privilege of leading the fifth summer drought simulation in the experiment’s history.
The experiment combines open-top chambers to simulate warming and a pump system to periodically lower water tables by around 20cm, simulating a summer drought every four to five years for around 26 days. The summer drought I conducted in 2024 allowed us to measure the peatland’s carbon response to climate pressures through greenhouse gas fluxes, soil and water samples, and even tea bags. Tea bags are used as an indicator of soil decomposition over time, using black tea as a standardised substrate.
Cors Fochno is one of the largest active lowland raised bogs in the UK (Photo credit: Nina Overtoom).
Water table depth measurement at one of the experimental plots at Cors Fochno with a warming and drought treatment (Photo credit: Katja Mirzai).
A pumping system was set up to artificially lower the water table in experimental plots (Photo credit: Nina Overtoom)
Vegetation survey in 2024 adds to the long-term vegetation dataset of the site (Photo credit: Simon Caporn).
Fieldwork at Cors Fochno was both rewarding and challenging. Each day, I crossed the boardwalk to the central dome, surrounded by rare species like Sphagnum mosses and sundews (Harris, Bryant, and Baird, 2006). Conducting and monitoring the field experiment required braving all weather conditions to collect samples, measure greenhouse gas fluxes, repair sensors, and ensure the water pumps ran smoothly. The long days in the field, surrounded only by mosses, heather and the occasional lizard or red kite, were a powerful reminder of the privilege of studying such a rare and almost otherworldly ecosystem.
The experiment’s strength lies in its long-term monitoring. Data collected before, during, and after the drought, combined with 14 years of data, helps us understand peatland dynamics under climate change. In 2024, I collected over 1,000 soil samples, 300 water samples, and 500 tea bags, alongside measurements of greenhouse gas fluxes, water table depth and temperature. ECT and the Ramble Worldwide Outdoor Trust supported the replacement of essential monitoring equipment at Cors Fochno. A follow-up visit in November assessed the peatland’s recovery, with water tables showing signs of rebound.
Sphagnum mosses in the droughted experimental plots at Cors Fochno (Photo credit: Nina Overtoom).
A combination of methods is used to study peatlands, such as soil samples, soil water samples, field pH measurements and greenhouse gas fluxes (Photo credit: Nina Overtoom and Katja Mirzai).
This ongoing work is vital for understanding the resilience of peatlands as carbon stores under increasing climate pressures. Over the coming months, greenhouse gas and laboratory analyses will uncover how microbial communities, nutrients and enzymes and environmental variables interact in these ecosystems. By contributing to this long-term study, I hope to reveal critical insights into the intricate processes driving the responses of peatlands to climate change.
