| 05 Oct 2026
Heather management modifies climate sensitivity of surface peat moisture in UK upland peatlands
Abstract. UK upland peatlands are important carbon stores, often dominated by heather, and are increasingly threatened by climate change, which promotes peat drying and wildfire risk. While water table depth (WTD) is often monitored to assess peatland hydrology, many key ecohydrological processes depend on surface peat moisture (SPM), which directly regulates surface carbon cycling, vegetation dynamics and peat fire risk, yet SPM remains poorly understood. We analysed seasonal SPM measurements under unmanaged, mown and burnt heather over 12 consecutive years post management from three replicated deep peat sites, together with measurements over five weeks of wet to dry conditions at a shallow peat site spanning three years post management. Across the deep peat sites, climate primarily controlled SPM, while heather management buffered moisture losses, particularly during warm and dry conditions. This buffering effect was strongest soon after management and weakened during vegetation recovery as heather height increased. After excluding low-rainfall events, SPM was strongly related to WTD, and the relationship remained relatively stable when the water table was within ~35 cm of the peat surface. At the shallow peat site, management substantially increased SPM during the first year after treatment relative to old heather, while mowing maintained higher SPM three years post-management, particularly under very dry conditions. Overall, heather management increased SPM across both peatland types, creating wetter near-surface conditions and reducing the sensitivity of surface-moisture to climatic drying. While mowing generally produced more consistent increases in SPM than burning, retained brash may increase wildfire risk under future climate change. The relative benefits of management types are likely to depend on site-specific conditions and time since management.
Competing interests: The authors received funding from a variety of sources reflecting the wide range of interest in peatland management. The research builds on the Peatland-ES-UK project which is not about grouse moor but heather management for ecosystem services. Importantly, the funders of the Peatland-ES-UK project had no influence on this paper and on balance are likely indifferent or against heather burning, and were from multiple sources, in order of highest amount of funding to lowest these are: Defra, NERC, two water companies, the Law Family Charitable Foundation, the Moorland Association, the British Association of Shooting and Conservation and further smaller funding from the Heather Trust, Yorkshire Peat Partnership, Natural England and the Ecological Continuity Trust.
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