Going for the burn – research shows impact of burning moorland heather
Heather burning has been used for generations to prompt re-growth on moorland environments. Now new research has been conducted into its value
Burning patches of heather is commonly used for moorland management, both here in the Westcountry and, more controversially in the north of England and Scotland where moors are managed for the benefit of red grouse, a quarry species for shooting interests.
A study commissioned by the Game and Wildlife Conservation Trust used aerial photographs and fieldwork to look at the long-term effect of rotational burning on moorland vegetation.
It found heather cover dropped after a burn, and gradually rose to almost complete ground cover on areas burnt more than 17 years before. The highest levels of sphagnum moss and cotton grass were found on areas burnt between three and ten years previously, and were very low more than 17 years after a burn. The GWCT – a procountry sports organisation that carries out extensive research into rural management – said it believed the results in the paper supports other studies which find the highest cover of sphagnum mosses within ten years of rotational burning.
The GWCT reports: “Burning is a commonly used tool to manage the vegetation on heather moorland, especially but not exclusively where it is managed for red grouse. It is used to stop heather growing too tall and woody, and, after the burn, heather regenerates to give new growth, which is considered to be more nutritious and palatable for grouse to eat. Heather burning for this purpose is performed in a cycle, with different patches burnt each year in winter, with the aim being a quick, cool burn that does not affect the peat underneath. It gives a patchwork of different height areas for grouse and other wildlife.
“Rotational burning has been a traditional management tool for centuries, but recently it has been the subject of much debate, with concern that it can be environ- mentally harmful, especially when it is done on blanket bog.
“Some studies have found evidence that heather burning promotes heather growth, at the expense of other plant species. But a long-term study carried out at the Moor House National Nature Reserve in the North Pennines, running from 1954, showed that carrying out prescribed burning on a ten-year rotation increased the cover of peat-building species like sphagnum moss and cotton grass.
“Sites with longer burning cycles had more heather and fewer species that are thought of as peatbuilding (all plants can build peat, but some do so more quickly than others).
“Because this study at Moor House has given so much information about the impact of heather burning, much of what we know in the field is based on its findings. It is important to look at other sites to see whether the findings apply more widely.
“This study looks at the effect of heather burning on vegetation at different times after burning on another moorland site in the Pennines, to test the finding from the Moor House experiment on a site that is actively managed as a grouse moor.”
The study looked at moorland which is managed for red grouse and has significant areas of blanket bog. It examined how the vegetation responded after different time intervals since burning. It found heather cover was lowest in the plots that had been burned most recently, gradually increasing in cover over time while the cover of sphagnum mosses was low after a burn, increased to be highest in the categories burnt three-six and seven-ten years ago, before levelling and declining in the older burns. Cover for cotton grasses was low straight after the burn, then rose in the three-six and seven-ten year categories and dropped off again in 11-17 to be low in the 17+ year categories.
The GWCT concludes: “Other papers have recommended that to maintain plant biodiversity on moorland, rotational burning or cutting should be carried out when the heather reaches 25cm in height, and that if it is allowed to reach 40cm, most other species will be lost and would then have to regenerate from the seed bank or recolonise from other areas after burning or cutting.
“This study represents the findings at only one site, and it was not possible to consider unburnt areas for reference. It adds to our knowledge in the field, and supports the findings at nearby Moor House, but more research is needed to understand the subject more fully and at a wider range of sites. This study does suggest that in the shorter term after rotational burning, it is the peat-forming species that benefit.”
‘Rotational burning has been a traditional management tool for centuries’
Swaling on Exmoor – controlled burning of the heather is common in moorland environments across the UKRICHARD EALES