Peatland-ES-UK

In 2012, Defra initiated the Peatland-ES-UK (Peatland Ecosystem Services UK) project to investigate impacts of heather burning versus alternative cutting or no heather management across three sites. The study is based on a paired catchment design, comparing burning to cutting and also includes fully replicated plot-level comparisons to assess no management options and assess brash impacts. Management change was only started after one year of initial monitoring to capture generic differences between plots and catchments before experimental management interventions.

This is the only such Before-After Control-Intervention (BACI) study to investigate management impacts holistically, capturing not only impacts on carbon but also on greenhouse gas emissions, water storage and quality and biodiversity aspects.

Heather moorlands are a globally rare habitat, of which much is located in the UK. Many of these upland areas consist of blanket bogs, a type of peatland which accumulated up to several meters of peat. The reason for this peat formation is the slow decomposition of organic matter under cold and wet climate. These ecosystems are not only vital stores of carbon but also harbour rare biodiversity. However, these habitats and their ecosystem functions are increasingly under threat by climate change. As climate warms and rainfall patterns change, this changes the naturally cold and water logged conditions. In addition, past drainage to improve the land for agriculture and grazing has caused much degradation of these peatland habitats, causing loss of carbon and biodiversity. Moreover, an often contentious issue is the management of heather for red grouse. This historic management consists of rotationally burning small areas of heather to rejuvenate the vegetation and improve grazing nutrition. The resulting patchwork of growth stages with varying vegetation compositions provides important habitats for many plant and animal species. 

More recently, there have been many claims about negative impacts of heather burning on carbon, biodiversity and water aspects. However, many of those claims are not supported by robust science. Most studies were too short (i.e., often less than 3 years) to capture anything but transient disturbance effects and too small scale (i.e., plots of a few square meters) to capture overall landscape scale impacts. Moreover, many studies were Space for Time studies, comparing management impacts across separate locations, often under different climatic and drainage conditions. Importantly, such studies cannot provide robust information on direct management impacts as findings are confounded by other factors such as often differences in climate and drainage explain observed differences.