1.2 Eligible Activities - Soil types & Landuse
- What are Organic, Organo-mineral and Mineral soils?
- Which soils are eligible for woodland creation under the Code?
- How do I confirm the soil type on my site?
Eligible activities shall be those relating to woodland creation on soils that are not organic (i.e. less than 50cm depth peat).
Adopting the precautionary principle, where it is possible that there are:
- organomineral soils, where the project includes a mosaic of habitat types, or
- important habitats (potentially areas of the project have been previously identified as ‘species-rich’ in an agri-environment scheme),
then peat depth, soil type and vegetation (NVC) surveys shall be provided at validation.
This requirement is only checked at validation.
For the purposes of the Woodland Carbon Code, we define woodland creation as the human-induced conversion to woodland of land that has not been under tree cover for at least 25 years. The woodland can be established by planting, direct seeding or natural colonisation/ regeneration.
Projects will need to prove that the land has not been wooded in the last 25 years. The following sources of evidence are suitable:
- Land use records
- Historical maps or images
- Forestry Commission England, Scottish Forestry, Welsh Government or Northern Ireland Forest Service planting/ felling databases
- Signed attestation from an independent expert
The carbon benefits associated with woodland creation are generally greatest on soils with lower organic matter content (such as mineral soils) and where establishment and management techniques disturb the soil as little as possible. We advocate ground preparation techniques with the minimum soil disturbance necessary for successful establishment.
Research is still ongoing to fully understand the changes to soil carbon as a result of landuse change and land management activities. We are adopt a conservative approach to soil carbon, ensuring that soil carbon emissions associated with the woodland creation project are not under-estimated and that any soil carbon sequestration associated with the woodland creation project is not over-estimated. This approach has been developed with the support of a group of soil experts from across the UK. See Soil Carbon and the Woodland Carbon Code.
A comparison of the soil classifications used in the soil surveys of England & Wales, Scotland and the Forest Research classification identifies which soil types are organic, organo-mineral and mineral.
Organic Soils: In Scotland and Northern Ireland, organic soils are those with an organic layer of at least 50cm. In England and Wales they are have an organic layer of at least 40cm. The Forest Research classification suggests an organic layer of > 45cm. These organic soils can also be known as peats in Scotland and Northern Ireland and deep peats in England and Wales.
Organo-mineral Soils: In Scotland and Northern Ireland, organo-mineral soils have an organic layer of 50cm or less, and in England and Wales 40cm or less. Forest Research’s classification, suggests an organic layer of < 45cm. These can include humus-iron podzols, peaty podzols, surface and ground water peaty gleys, peaty rankers and podzolic rankers.
Mineral soils are not defined as having an organic layer (primarily composed of decaying plant material) although they do contain an organic horizon (with higher organic content than underlying horizons). Forest Research classifies mineral soils as having an organic layer of less than 5cm. These can include brown earths, brown rankers and rendzinas, cultivated podzols, surface water and ground water mineral gleys.
Mineral and Organomineral soils: Woodlands can be created on these soils within the Woodland Carbon Code.
On some soils with a deep organic layer the magnitude of soil carbon losses due to disturbance and oxidation can be greater than carbon uptake by tree growth over the long term. For this reason, in addition to habitat and biodiversity value, the Woodland Carbon Code does not allow any woodland creation to occur on soils with an organic (peat) layer of more than 50 cm.
Where it is likely that there are peaty soils, a peat depth survey should be carried out, and areas of deep peat excluded from the project.
Projects should assess the soil type onsite using one of the following methods:
- Using the following maps to check for areas of peat;
- The British Geological Survey 1:250,000 or 1:50,000 scale data for mapped areas of peat exceeding 100cm in depth.
- Soil Survey of Scotland, Soil Survey of England and Wales and Soil Survey of Northern Ireland 1:250,000, 1:63,360, 1:50,000 and 1:25,000 data for mapped areas of peat.
- FC soil maps for mapped 'deep peat' soil types.
- Ascertain soil type using one of the following tools;
- Field survey for soil type and where necessary, peat depth and vegetation
Peat Depth Survey
- Use GPS to set out a regular 50mx50m sampling grid across the site
- Use a peat probe measure and record the depth at each point
- If you need to show where the 50cm depth boundary falls, 3D Modelling packages can then estimate the '50cm depth' peat boundary if necessary. This can be affirmed or refined by probing on a 10mx10m grid as above.
- We will add a comparison to the Soil Classification in Northern Ireland
- We will develop a soil assessment protocol which, for soil type and soil carbon content