Interviews with Professor Graeme Swindles and John T. Van Stan II, Ph.D. for PLOS One article: Climate and water-table levels regulate peat accumulation rates across Europe

Interview with Professor Graeme Swindles, School of Natural and Built Environment, Queen’s University Belfast, U.K.

Author of PLOS One paper: Swindles GT, Mullan DJ, Brannigan NT, Fewster RE, Sim TG, Gallego-Sala A, et al. (2025) Climate and water-table levels regulate peat accumulation rates across Europe. PLoS One 20(7): e0327422. https://doi.org/10.1371/journal.pone.0327422

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What first drew you to study peatlands across Europe, and why are they important?

I was drawn to study peatlands across Europe because they store carbon and are characterized by unique ecosystems. Yet peatlands are often overlooked in climate strategies. They are important because protecting and restoring them can play a major role in tackling climate change while safeguarding biodiversity and water quality.

What did you choose to investigate in this study, and why?

We investigated the patterns of vertical peat growth rates and how these are influenced by climate and hydrological regime. This is a fundamental question if we are to understand how peatlands function and their response to climate change and human impacts.

What are the key findings from your research?

Our study suggests that, in some European peatlands, higher summer temperatures may enhance growth rates, but only if a sufficiently high water table is maintained. In addition, our findings corroborate contemporary observational and experimental studies that have suggested an average water-table depth of ~10 cm is optimal to enable rapid peat growth and therefore carbon sequestration in the long term. This has important implications for peatland restoration and rewetting strategies, in global efforts to mitigate climate change.

What most surprised or interested you about your findings?

How closely our results correspond to other studies using very different methods. 10cm is a ‘magic number’ for peatland functioning.

What did you learn about differences in peat accumulation rates in different regions of Europe? Where are rates highest and lowest?

Lowest accumulation rates are in sub-arctic regions, whereas the highest rates are in Scandinavia and Continental Europe.

You suggest that higher summer temperatures could enhance peat growth rates if a high water table is also maintained – what are the optimal summer temperatures, and what is too high?

It may depend on the type of peatland and its hydroclimatic setting, future research is needed to fully quantify these relationships.

Do you think your research can inform future peatland management and restoration strategies? If so, how?

Yes. Our work provides a long-term context to support the idea of an optimum water-table depth for maximum peat accumulation. This is a fundamental result for underpinning effective peatland restoration.

What do you hope your findings might lead to, and what are the next steps for your research?

Better peatland restoration practices to maximise peat accumulation and carbon sequestrations. The next steps for this research are to extend the work into different regions, and across longer timescales.

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Interview with John T. Van Stan II, Ph.D., Associate Professor of Natural Philosophy at Cleveland State University, U.S.

Associate Editor of PLOS One paper: Swindles GT, Mullan DJ, Brannigan NT, Fewster RE, Sim TG, Gallego-Sala A, et al. (2025) Climate and water-table levels regulate peat accumulation rates across Europe. PLoS One 20(7): e0327422. https://doi.org/10.1371/journal.pone.0327422

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What kind of research are you engaged in yourself, and what experience do you bring to your assessment of this paper?

I'm an ecohydrologist studying plant-water interactions during wet conditions (rain, snow, fog, etc.). As Associate Editor for PLOS One, I handle manuscripts on biogeochemical research and restoration strategies, giving me a broad view of peatland research and its applications, although my direct research experience regarding peatlands is scant. I suppose I bring an almost-outsider perspective - someone within the broader discipline, but not fully nestled in the sub-discipline.

Can you tell us what the authors chose to study?

They compiled paleoenvironmental data across European peat bogs to quantify apparent peat accumulation rates (aPAR) and examine how climate and reconstructed water-table depth control those rates. Their approach is impressive because it brings together two millennia of high‐resolution paleoenvironmental records from 28 distinct European peat bogs, giving unprecedented temporal depth and geographic breadth to robustly link long‐term peat accumulation with climate and water‐table dynamics.  

What do you think are the key findings from their research?

They show that European peatlands accumulate peat at rates between 0.005 and 0.448 cm per year (mean ~0.118 ), that warmer summers generally boost accumulation rates, and that an optimal water-table depth of roughly 10 cm below the surface maximizes long-term peat growth. What makes this interesting is that it transforms two millennia of buried carbon into a clear, quantifiable target for designing and evaluating peatland restoration across diverse climates.

What most surprised or interested you about their findings?

These results are crucial for guiding peatland restoration under climate change because they show, over two millennia and 28 sites, that peat growth is driven by the interplay of climate, vegetation type, and water-table depth (with geographic variation) and thus validate short-term experimental targets on geological timescales

Why are you so enthusiastic about this research?

Because it bridges contemporary experiments and palaeoecological records to define a clear, evidence-based target for peatland restoration that can improve carbon sequestration and inform global climate-mitigation efforts.

What impact do you hope this study might have?

I hope it inspires a renewed sense of wonder for peatlands as living archives and powerful carbon sinks, encouraging scientists, policymakers, and the public alike to cherish, protect, and restore these remarkable ecosystems.

Interviews edited by PLOS staff for clarity and concision.