Agro-forestry is the integrated use of trees on a farm or small holding for a wide range of benefits.  The Scottish Government has set statutory targets for the reduction of GHG emissions in Scotland through the Climate Change (Scotland) Act 2009. Agroforestry in Scotland is one option that could help achieve these targets, while also supporting sustainable adaptation to a changing climate.

This report identifies the wide range of potential benefits of increasing the use of agroforestry practice in Scotland and will support further discussion towards implementation.

The Scottish Government’s ambition is to increase woodland cover in Scotland to 25% by the second half of the century. The Scottish Climate Change Plan (2017) has an ambition to increase from the current 18% to around 21% of woodland cover by 2032. This will make an important contribution to reducing Scotland’s net greenhouse gas (GHG) emissions.

However, it is important to understand the consequences of forestry activity, given that approximately two-thirds of Scotland is covered by high carbon-content organic soils of varying depths, including nearly a quarter with deep peat soils

This report examines new evidence published since the Forest Research report ‘Understanding the GHG implications of forestry on peat soils in Scotland’ (Morison et al., 2010). The review broadly confirms the findings of the 2010 report. It remains probable that moderate and high productivity forests planted on shallower peat soils with limited disturbance provide a substantial net carbon uptake over the forest cycle.

Soil carbon, or the content of carbon housed within soil, plays a significant role in the release and absorption of global greenhouse gas emissions. Changes in land use contribute to release of this carbon, and Scottish Government is interested in the potential implications of such change across several policy areas.

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.

Key findings:

• 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.