The Press and Journal (Aberdeen and Aberdeenshire)

Does burning the heather do more harm than good?

- Davy McCracken Davy McCracken is professor of agricultur­al ecology and head of SRUC’s Hill and Mountain Research Centre at Crianlaric­h

Muirburn involves the controlled burning of old heather and grass to promote new growth.

It is a tool used traditiona­lly by a wide range of land managers in Scotland, including gamekeeper­s, hill farmers and crofters.

It is primarily used to improve grazing for livestock or provide food and shelter for red grouse, but it is also perceived to reduce wildfire risk.

The Muirburn Code sets out statutory restrictio­ns and good practice for land managers who burn moorland vegetation.

Currently muirburn can take place between October 1 and April 15 (or April 30 with the permission of the landowner) without a licence.

However, the benefits and disadvanta­ges of muirburn are contested.

In particular, there are concerns about the continuati­on of muirburn, especially on peatlands, at a time when we are trying to address the ongoing climate and biodiversi­ty emergencie­s.

My team at the farms, together with colleagues from SRUC Edinburgh, recently completed a review for NatureScot of the available evidence on the impacts of muirburn on wildfire prevention, biodiversi­ty conservati­on and carbon sequestrat­ion.

The research published to date has focused on a limited number of sites across the UK and has mostly taken place on blanket bog.

The latter is not representa­tive of all moorlands on which muirburn may be conducted. This, and the overall lack of studies available, limited the conclusion­s we could draw.

The known impacts on biodiversi­ty are mostly clear-cut but are neverthele­ss mixed.

There are winners and losers, but how these are viewed depends on a land manager’s objectives and the biodiversi­ty under considerat­ion at a site.

Wading birds such as curlew and lapwing are often said to benefit on managed grouse moors, but it is difficult to disentangl­e the benefits specifical­ly arising from muirburn from the additional benefits that predator control provides. There have been very few studies considerin­g full carbon budgets on muirburn sites. The vast majority of these have focused on the impact of burning on what is called dissolved organic carbon.

This refers to a complex mixture of compounds that represent a key component of the carbon cycle from land into freshwater and marine systems. While it is important to understand these processes, these studies did not consider what impact muirburn may be having on the carbon stored in the soils.

Finally we found that there have been no real direct studies on the associatio­n between muirburn and wildfires.

Any previous conclusion­s have been drawn indirectly from the fact that reducing vegetation biomass – or fuel load – on a moorland through muirburn might be expected to reduce the risk of any subsequent wildfire.

This has, however, not been studied specifical­ly for muirburn.

Conversely, there is some evidence to suggest that a proportion of muirburn leads to wildfires. The exact proportion is unknown, nor what type of muirburn may have a higher likelihood of developing into such wildfires.

Our review was commission­ed by NatureScot because an independen­t group set up by the Scottish Government, the Grouse Moor Management Review Group, produced a report in 2019 that made a number of recommenda­tions, including introducin­g legislatio­n to require a year-round muirburn licence.

NatureScot will now form a small sub-group of their Scientific Advisory Committee to provide them with advice on how to take a risk-based approach to muirburn licencing in the face of an unclear evidence base. It is, however, essential that hill farmers and crofters are aware that the 2019 report made clear that the licensing regime will apply to all muirburn and not just that carried out on grouse moors.

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 ?? ?? BURNING QUESTION: Muirburn has been practiced for centuries but do the benefits in land management outweigh its harm to the environmen­t?
BURNING QUESTION: Muirburn has been practiced for centuries but do the benefits in land management outweigh its harm to the environmen­t?

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