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3.4 Project Carbon Sequestration

What is project carbon sequestration?

Project carbon sequestration is the changes to carbon stocks on the site over the project duration as a direct result of the project.  To establish the net benefit of the project this will subsequently be compared to the baseline scenario (changes that would have happened to carbon stocks on the site without the project) and adjusted for any leakage (emissions outside the project boundary as a 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.


Which carbon pools do I include?

The following carbon pools shall be included in project carbon sequestration:

  • Tree biomass (Above and below ground)
  • Litter and deadwood
  • Non-tree biomass (Above and below ground) at project outset
  • Soil
  • Greenhouse gas emissions from woodland management


Vegetation removed at start of project 

Guidance on carbon baselines describes further how to calculate the carbon stock at the site at the start of the projectThe carbon stock of any vegetation removed prior to the start of the project should be accounted for (both tree and non-tree biomass).  This shall be shown as an emission in year 1 of the project carbon calculations.  Projects can contact us 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 tree biomass (above and below ground) and debris

In order to predict future carbon sequestration, projects shall use the 'Carbon Lookup Tables' and associated guidance available here.  These tables are pre-calculated predictions for a given number of situations including species, planting density, management regime and potential growth rates, or yield class.  They are based upon our knowledge of the growth rate of trees and their uptake of carbon over time.  The Lookup Tables provide a quick and easy way to 'look up' the amount of carbon that is likely to be sequestered in above and below ground tree biomass as well as debris by choosing the situation which most closely fits a particular woodland.  Emissions from ongoing woodland management are also included in the Carbon Lookup Table.  See how they were constructed.

NOTE That whilst the Woodland Carbon Code has tried to ensure that the number of Pending Issuance Units listed for sale for each project is conservative, based upon the Carbon Lookup Tables, project developers should bear in mind when agreeing to sell PIUs that the Carbon Lookup Tables 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.


Carbon in the soil

Projects shall estimate changes to soil carbon as a direct result of the project activities.  This includes any losses to soil carbon at the start of the project as a result of site preparation activities, as well as any gains to soil carbon as the project progresses.   

Soil Carbon and the Woodland Carbon Code sets out the methodology for Organomineral and Mineral soils.  Projects can either

  • make a soil carbon assessment prior to tree planting with repeat assessments as the project progresses or
  • follow the metholology set out which uses the best data currently available to estimate changes to soil carbon

Soil Carbon Losses at the start of the project are included in the Example Carbon Calculations Spreadsheet

Soil carbon accumulation can currently only be claimed for projects on a mineral soil where the previous landuse was arable or rotational grass and the woodland will be managed as minimum intervention.  See the Soil Carbon Lookup Table.

Section Eligibility - Soil Type explains what soil types are eligible and how to assess the soil type.  Carbon Baselines explains how to estimate the amount of soil carbon prior to the start of the project. 


Emissions from Woodland Establishment and Management

Projects should account for emissions from woodland management according to the the Guidance on using the Carbon Lookup Tables.

  • Emissions from establishment activites should be accounted for in year 1 of the project. 
  • Emissions from ongoing management activites (i.e. thinning) is included within the Carbon Lookup Table.
  • Emissions from clearfelling, if this type of management is proposed, should be included in the year(s) that the clearfell cap is reached.


Future developments

    • Non-tree biomass
      • We will publish estimates of the carbon stock of other types of non-tree vegetation.
    • Tree biomass:  We are developing a model which will be more 'project-specific' and allow more precise predictions of future carbon sequestration by allowing for a wider range of situations.  For a more precise estimate of future carbon the user will be able to give more details in terms of
      • Species and species mixes
      • Management regime (eg number and frequency of thinnings, intention of continuous cover system)
      • Site information
    •  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
    • Emissions from woodland establishment and management
      • We will update the method by which emissions from clearfelling are accounted for.



Last updated: 5th August 2017