This evidence assessment looks at the current state of knowledge on the impact of muirburn on peatland and peat soils.
Prescribed burning of moorlands has been used for centuries as a land management tool to remove less productive vegetation, mainly heather, and to encourage new growth. Originally used to increase productivity for sheep and cattle grazing, it is also now widely used to improve the habitat for red grouse. In Scotland, this is referred to as muirburn.
Carrying out muirburn as a land management tool, known as ‘prescribed burning’, is tightly regulated in Scotland, summarised in The Muirburn Code which was last revised in 2011.
- During burning there is a clear loss of vegetation (carbon). However this is replaced as the vegetation recovers during the burn cycle. What is not clear is whether there is a loss of carbon from peat soils.
- The evidence for a net loss of carbon dioxide is unclear.
- The timing of muirburn on peatland is critical, in that the vegetation should be dry enough for it to burn well while at the same time the ground should still be wet enough to prevent combustion of the ground litter and the peat itself.
- There is not enough evidence to judge the impact of vegetation type or age on greenhouse gas emissions.
- The main factor affecting the rate of carbon sequestration post-muirburn is the nature of the recovering vegetation and whether it is grazed or not.