How does our understanding of historic peatlands imform our approach to restoration practices?

Peatlands are among Europe’s most valuable yet underappreciated ecosystems. Covering ~10% of the continent’s land area, these waterlogged landscapes store vast amounts of carbon—more than all European forests combined. Formed over thousands of years through the slow accumulation of decaying plant matter, peatlands act as powerful carbon sinks, however they become major carbon sources when drained or degraded.

Despite their importance, many of Europe’s peatlands have been altered for agriculture, forestry, or peat extraction, releasing centuries’ worth of stored carbon into the atmosphere. As the urgency to combat climate change intensifies, scientists and policymakers are turning their attention to peatland restoration and conservation as a vital natural climate solution. Major efforts are already underway to conserve and restore peatlands across Europe, including LIFE Peat Restore, a major “re-wetting” project focused on revitalizing degraded peatlands, however improved scientific understanding of the factors which contribute to peat formation, and the stabilization of these carbon sinks, is vital to allow refinement of peat revitalization projects.

PLOS One paper “Climate and water-table levels regulate peat accumulation rates across Europe” from Graeme Swindles and colleagues, explores a key piece of that puzzle: identifying the optimal conditions for peat formation and sustained growth, with the goal of enhancing peatlands’ role in long-term carbon sequestration.

This study explored apparent peat accumulation rates (aPAR) across 28 European peatlands during the last two millennia to further understanding of how fast peatlands grow vertically, identifying optimal ranges for important contributing factors, and validating peatland development models based on these variables. The study supported the assertion that European peatlands accumulate at ~0.1 cm/year (0.118 cm/year) whilst also demonstrating variability (0.005 to 0.448 cm/year) across the sites. Higher summer (June, July, August) temperatures were found to associate with higher aPAR values, with a more robust association for minimum aPAR and summer temperatures. aPAR was also shown to be generally lower under deeper water tables, with suggestion of a hydrological threshold for optimal peat accumulation, as a negative impact was found both when water tables are very low and when they are in excess of 25 cm.  

Higher summer temperatures are linked to increased peat accumulation due in part to increased plant growth, which results in increased organic matter for degradation into peat. It is noted however that moisture levels also play a significant role, and increased temperatures without adequate moisture can negatively impact overall peat formation and stability.

John T Van Stan, the PLOS One academic editor who oversaw peer review of this article, was impressed with the authors methods, which provided unprecedented temporal depth and geographic breadth in robust support of the findings.

These findings have implications for future peat restoration projects, which rely on a delicate combination of climate and water conditions. This work may also assist in efforts to evaluate previous peat restoration programs, and inform changes necessary for future success.

In an interview about this research, Graeme Swindles shared that the authors were surprised at how closely their findings correspond with other studies utilizing different methods, validating the ‘magic number’ of water table level for peatland growth and stability. Further research is still required to elucidate the optimal temperature, however, and this is likely to vary depending on the type of peatland and its hydroclimatic setting.

Ultimately, the authors hope their work will inform improved peatland restoration practices, to maximize peatland accumulation for carbon sequestration and protection of the biodiversity these unique ecosystems support.

Author interview with Graeme T. Swindles: http://plos.io/4kz6YZh

Associate Editor interview with John T. Van Stan: http://plos.io/46ldrnd