The latest results from a five-year study suggest upland moor burning has a significant negative impact on the environment, causing important peat bogs to dry out, turning rivers more acidic and reducing the diversity of plants and animals able to survive in the habitat. Other effects include raised soil temperatures, an increased risk of flooding and higher silting of water courses.
Muirburning, as it is known in Scotland, is a traditional land management technique believed to have been in use since Mesolithic times (about 12,000-3,000 BC).
It is often carried out to promote new heather growth to boost grouse numbers for shooting. In some parts of the country, it is used to improve grazing and to prevent wildfires by restricting available fuel, and is occasionally used for conservation purposes.
Scientists from the University of Leeds involved in the Ember project assessed the impact of heather burning on upland peat moors across the English Pennines.
Lead researcher Dr Lee Brown said: “Until now there was little evidence of the environmental impacts of moorland burning.
“Unsurprisingly, a push away from moorland burning without solid scientific evidence to back up the need for change has created a lot of tension.
“The findings from the Ember project now provide the necessary evidence to inform policy.”
Researchers found the water table is significantly deeper where burning has taken place compared to unburned areas.
A lower level of saturation allows peat near the surface to dry out and degrade, releasing stored pollutants such as heavy metals into rivers and carbon into the atmosphere.
Co-researcher Professor Joseph Holden said: “Altering the hydrology of peatlands so they become drier is known to cause significant losses of carbon from storage in the soil.
“This is of great concern, as peatlands are the largest natural store for carbon on the land surface of the UK and play a crucial role in climate change. They are the Amazon of the UK.”
Blanket bog covers around 23 per cent of land area north of the Border.
Conservationists at the Scottish Wildlife Trust oppose muirburning on upland blanket bog.
Maggie Keegan, head of policy and planning at the charity, said: “If you think that it takes 1,000 years to form a layer of peat one metre deep, should we really be burning it?”
Scottish Gamekeepers Association chairman Alex Hogg hit back at critics of land management on sporting estates, widely acknowledged to help conserve rare black grouse.
“Rotational strip burning acts as a fire-break against wildfires, which scorch peat over large areas, releasing carbon into the atmosphere at a far more damaging rate than any controlled muirburn would,” he said.
The muirburning season runs until 15 April from today.