The Woodland Carbon Code (WCC) website - sequestered carbon: EIR release

Information requested

The WCC website does not appear to provide information on how the forecast sequestered carbon is calculated, with formulae contained within spreadsheets rather than in a separate, published paper.

Please could the WCC provide the WCC formulae determining how it predicts sequestered carbon for all tree species that are used for the WCC in the UK, in a clear and legible format, also showing the different formulae that are applied for each species if harvesting occurs, or does not occur, and over different timescales. There may be different formulae according to different soil types and other factors influencing carbon sequestration and growth rates, and/or there may be different parameters used in these formulae.

Response

As the information you have requested is ‘environmental information’ for the purposes of the Environmental Information (Scotland) Regulations 2004 (EIRs), we are required to deal with your request under those Regulations. We are applying the exemption at section 39(2) of the Freedom of Information (Scotland) Act 2002 (FOISA), so that we do not also have to deal with your request under FOISA.

This exemption is subject to the ‘public interest test’. Therefore, taking account of all the circumstances of this case, we have considered if the public interest in disclosing the information outweighs the public interest in applying the exemption. We have found that, on balance, the public interest lies in favour of upholding the exemption, because there is no public interest in dealing with the same request under two different regimes. This is essentially a technical point and has no material effect on the outcome of your request.

The WCC website does not appear to provide information on how the forecast sequestered carbon is calculated, with formulae contained within spreadsheets rather than in a separate, published paper.

Please could the WCC provide the WCC formulae determining how it predicts sequestered carbon for all tree species that are used for the WCC in the UK, in a clear and legible format, also showing the different formulae that are applied for each species if harvesting occurs, or does not occur, and over different timescales. There may be different formulae according to different soil types and other factors influencing carbon sequestration and growth rates, and/or there may be different parameters used in these formulae.

While our aim is to provide information whenever possible, in this instance we are unable to provide the information you have requested because an exception under regulation 10(4)(a) of the EIRs (Information not held) applies to the information you have requested.

Please see Annex A for the reason this exception applies.

Under regulation 9 of the EIRs (our duty to provide advice and assistance) we would like to provide further information which may be of interest.

The Woodland Carbon Code’s carbon calculator is based on models being routinely used and further developed by Forest Research. This paper on the construction of the lookup tables explains the background. The carbon calculator guidance may also be of assistance in understanding how the calculator works.

It’s not possible to give every formula, but we can point to the following tabs in the publicly available carbon calculator which will help aid understanding:

• Species lookup explains which species model is used for a wide range of tree species.
• Biomass carbon lookup table gives the predicted sequestration for each species, spacing, yield class and management option (thinned or not thinned) in 5-yearly intervals.
• Clearfell_max_seq_values gives the maximum amount that can be claimed for a given species, spacing, yield class, management regime (thinned or not thinned) for a given range of clearfell rotation lengths.
• When a user selects a given species, spacing, yield class, management regime and rotation length in the standard project carbon calculator tab, these values are ‘looked up’ and added to the calculation.

This paper outlines the approach to soil carbon in the woodland carbon code and explains where the figures come from that are used in the sol carbon emissions table on the standard project carbon calculator tab of the carbon calculator.

About FOI

The Scottish Government is committed to publishing all information released in response to Freedom of Information requests. View all FOI responses at https://www.gov.scot/foi-responses.