Scotland is a peat-rich nation. Healthy peatlands deliver a wide range of ecosystem services, including carbon sequestration, carbon storage and a specialised biodiversity.

However, much of Scotland’s peat resource is damaged: eroding, drained or converted to other land uses. The Scottish Government has made a significant commitment to restore peatland areas that have been damaged.

Peatlands restored to a functioning ecosystem can better withstand a changing climate and also provide vital flood risk protection. It takes time for the benefits of restoration to take effect.

This paper explores how we can monitor success. Long-term monitoring is important to track this recovery and prompt intervention when necessary.

Despite significant investment in peatland restoration we still have a lot to learn, particularly on the best techniques to use, and in understanding how long the process takes.

This project set out to review the current state of knowledge on the potential for carbon sequestration in key Scottish upland open habitats. Upland soils play a vital role in regulating greenhouse gas (GHG) emissions in our environment. Scotland’s soils contain 2500-3500 Mt of carbon, much of which is located in upland soil environments. This is equivalent to more than 200 years of Scotland’s annual greenhouse gas emissions. The management of uplands and their soils will therefore be critical to achieving Scotland’s ambitious net-zero emissions target.

Despite the well-known potential of soils to store carbon, however, there is uncertainty as to the long-term stability of this carbon pool. Increasing temperatures, altered patterns of rainfall distribution, and changes in land use all influence this process and threaten to reduce soil carbon stocks.

This review identifies the key drivers of change and covers three upland habitats: upland dry heath, upland wet heath and upland grasslands, defined by vegetation communities. It assesses potential GHG fluxes and the impact on biodiversity within these habitats.

It found very limited information regarding impacts on soil carbon stocks or GHG emissions; studies giving a full balance sheet of ecosystem stocks and flows of carbon in response to environmental or management change were particularly scarce.

Key findings include:
  • Scotland’s soils contain around 2,500-3,500 Mt of soil organic carbon. The various mineral, organo-mineral and organic soils found under moorland, montane, and rough grassland contain around 45% of total Scottish soil organic carbon stock.
  • Soil organic carbon accounts for 90% of the carbon stocks in these habitats. Therefore, studies which only consider changes in carbon held within the vegetation severely under-estimate changes in total carbon stocks.
  • GHG emissions in open upland habitats in Scotland occur as a result of emissions of carbon dioxide, methane and nitrous oxide. 
  • There is some evidence from Scotland that Molinia grasslands contain large carbon stocks within the vegetation, which are reduced by grazing.
  • When upland soils are left bare after excessive grazing or burning, there is a significant increase in the risk of soil carbon loss due to erosion.
  • The impacts of future climate change on carbon stocks are complex and are likely to depend on current and future management, soil type and vegetation communities. They have not been well researched in the Scottish context: this is a substantial gap in knowledge.
  • The review found an important knowledge gap on the interactions of drivers on GHG emissions, carbon stocks and biodiversity.

The boundary between productive land and hill land in Scotland has moved over time, in response to climate and also to market demand. Scotland’s climate is changing, and this will mean changes for those areas of Scotland that sit on the margins of productive agriculture.

In this context sustainable soil management is a specific challenge as Scotland adapts to a changing climate.

This report examines the four dominant ways that farmers will adapt to climate change, and their impact on different services.

Key findings:
  • It is likely that land use change will result in the intensification of land management. The result would be a reduction in most aspects of natural capital including soil carbon, water quality and biodiversity. An increase in arable cropping from current levels and a switch to winter cereals could increase soil erosion and flood risk.
  • An exception would be the potential increase in forestry and woodland, though the benefits ofplanting depend greatly on what is planted and where it sits within the landscape or catchment.
  • It is particularly difficult to assess the likely changes in livestock numbers. This makes it difficultto assess the greenhouse gas emissions from their rearing, as it is not possible to predict thebalance of their removal to allow arable cropping, the increase in extensive livestockmanagement which would affect emissions intensity, and the intensification of management oncurrently more marginal ground.
  • One approach to assessing the risk of autonomous adaptation would be to model the impacts of a set of scenarios of change so that comparison could be made with changes expected from other drivers; if potential impacts are large in comparison then greater attention would need to be given to strategies to avoid or mitigate impacts. 

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.