3.3 Project carbon sequestration



Future developments


    • Project developers shall use the relevant template Carbon Calculation Spreadsheet (Standard or Small Project tab) to predict the project carbon sequestration.
    • Emissions resulting from the preparation of a site prior to planting shall be calculated and subtracted from the project carbon sequestration at year 1. This includes losses of carbon through removal of vegetation (trees or other biomass) or disturbance of the soil.
    • Carbon sequestration in woodland biomass shall be restricted to the long-term average carbon stock that is projected to accumulate on the site.


    What is 'project carbon sequestration'?

    Project carbon sequestration is the changes in carbon stocks due to woodland creation over the project duration as a direct result of the project.

    This page outlines how to predict changes to carbon stocks that will occur over the duration of the project. The monitoring section explains how to assess actual carbon stocks later on in the project once the trees are growing and carbon has been sequestered.

    Project developers should bear in mind when agreeing to sell Pending Issuance Units that the tools here provide a prediction of the carbon that is likely to be sequestered and not a guarantee that a particular woodland will sequester a certain amount.

    Accounting for project carbon sequestration

    Projects should account for project carbon sequestration using the Carbon Calculation Spreadsheet version 2.4.1 April 2024 (xlsx) following the associated guidance (pdf). The calculator includes the following:

    • Emissions from establishment activities, ongoing management and clearfell. 
    • Emissions from soil disturbance
    • Sequestration in tree biomass, litter and deadwood (and in a limited number of scenarios, soil)

    Small projects (5 hectares net planting or less): Can use the 'Small Project Carbon Calculator' which is simpler to complete and conservative. Projects using this prediction tool can use the less intensive 'basic monitoring' from year 15 onwards.

    Standard projects: Should use the 'Standard Project Carbon Calculator'.

    Vegetation removed at start of project

    If any vegetation is removed prior to the start of the project, this should be accounted for (both tree and non-tree biomass). Projects can use Natural England's Carbon Storage and Sequestration by Habitat or This email address is being protected from spambots. You need JavaScript enabled to view it. for further information on estimates of the carbon stocks of non-tree biomass. They can also refer to the IPCC 2003 Good Practice Guide for Land Use, Land-Use change and Forestry and the IPCC 2006 Guidelines for national GHG inventories for guidance on estimating the carbon stock of existing vegetation.

    Carbon in the soil

    Soil Carbon and the Woodland Carbon Code sets out the methodology for organomineral and mineral soils. The Carbon Calculator includes assumptions about the likely soil disturbance and soil greenhouse gas emissions. Alternatively, projects can make a soil carbon assessment prior to tree planting with repeat assessments as the project progresses.

    Soil carbon accumulation can currently only be claimed for projects on a mineral soil where the previous land use was arable or rotational grass and the woodland will be managed as minimum intervention. This is included within the Carbon Calculator.

    Future developments

    • Tree biomass: Data behind the Carbon Calculator is being reviewed and revised to incorporate new growth and yield models and to refine estimates of contributions from root and branch biomass. The revised estimates for some tree species may be more conservative than current predictions, particularly for the early growth period of broadleaved species. The Carbon Calculator already subtracts 20% from modelled predictions and it is anticipated that these revisions will fall within this threshold.
    • Tree biomassWe will develop our Carbon Calculator to include a wider selection of spacings and to account for the carbon stored in roots and stumps when clearfelling.
    • Non-tree biomass: We will publish estimates of the carbon stock of other types of non-tree vegetation.
    • Soil. There will be a number of developments:
      • We will update the soil carbon methodology using results of ongoing research. This will allow us to say with more certainty both the amount of soil carbon lost on woodland establishment as well as the rate of accumulation of soil carbon as the woodland grows and matures.
      • We will establish a soil carbon assessment protocol to enable projects to consistently assess the soil carbon content of their soil. 
      • Ongoing research will help us better understand the changes to soil carbon due to woodland creation and management.

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