Scottish Forestry - Woodland Carbon Code information: EIR Review

Information requested

Original request: 202600513712

1). The Woodland Carbon Code (WCC) version 3.0 (January 2026) provides links to a document titled ‘Soil Carbon and the Woodland Carbon Code’ (Vicky West, 14 July 2011, 10 pages). This document claims on page 5 that:

Research recognises that there can be initial losses to soil carbon on organomineral soils, but that depending on the intensity of the ground preparation and ongoing management, there can be subsequent gains to soil carbon as woodlands grow and mature.

In respect of the above paragraph, it appears that the ‘initial losses’ are supposedly determined through a percentage loss of carbon from the soil due to disturbance resulting from forestry techniques such as hand turfing, mounding, ploughing and scarifying (as referred on pages 5-6).

However, the same sentence says (for organo-mineral soils) ‘there can be subsequent gains to soil carbon as woodlands grow and mature’. Please could you provide and/or identify the specific research source(s) that reaches this conclusion.
Although the document has eight references (page 9), it is unclear if any of these items of research contains the assertion (and if this is substantiated) that ‘there can be subsequent gains to soil carbon as woodlands grow and mature’.

2). Page 5 of this same (14 July 2011) document states:

Further research in the next 2-3 years will allow us to develop more reliable figures for rates of soil carbon accumulation. Results of this research will be used in the next Woodland Carbon Code update on soil carbon. Projects will be able to update their soil carbon estimates at the first verification, based this research and update.

In respect of the ‘further research in the next 2-3 years’ being used to ‘develop more reliable figures for rates of soil carbon accumulation’, please could you provide the research paper title(s) and author(s) of all research relating to potential post-planting soil carbon changes, not just for the 2-3 years after July 2011, but up to the present day. The above sentence seems to make the presumption that soil carbon accumulates post-planting (presumably after allowing for carbon losses from initial disturbance). As this research may instead show soil carbon is lost post-planting (long after initial disturbances to soil through establishment preparation and planting), it appears Scottish Forestry/WCC might also hold research and/or information from July 2011 to the present day demonstrating that soil carbon is lost over the longer term, not just from initial disturbances to soil through preparation and planting. Please ensure these research paper titles and authors are also provided.

Note: when I refer to soil carbon losses over the longer term, I mean soil carbon losses that are not due to disturbance to the soil through establishment preparation and planting (such as hinge mounding or scarifying), but due to physical, biological and other changes occurring due to the introduction of trees to the soil, and the subsequent growth of these trees over the long term (years and decades).

3). Page 5 of the 14 July 2011 document states ‘Results of this research will be used in the next WCC update on soil carbon’. If this research exists (and has been requested above in point 2), was this research actually published, and where? Was this research used to update any future WCC(s), and if so, which updates did they feature in?

4). If there was research suggesting soil carbon increases over time and this was used to update the WCC, have projects subsequently been able to ‘update their soil carbon estimates at the first verification’?

5). Given the 14 July 2011 document suggests ‘there can be subsequent gains to soil carbon as woodlands grow and mature’ it is unclear as to what the previous or current assumptions of the WCC are in relation to changes in soil carbon after the initial establishment phase. Is it the case that the WCC version 3 and all previous versions assume (or assumed) that there is no change in soil carbon for the duration of the project after the initial loss of soil carbon due to the initial establishment phase?

6). Research has shown that carbon continues to be lost from the soil for many years after planting for some sites, thus contradicting (a) the suggestion in the 14 July 2011 document that organo-mineral soils gain carbon over time after planting, and (b) any assumptions (potentially held by the WCC and others) that soil carbon in organo-mineral soils remain constant over time after planting.

For example, a paper by Friggens et al. (2020) ‘Tree planting in organic soils does not result in net carbon sequestration on decadal timescales’, appears to demonstrate that soil carbon decreased significantly for some sites. Another paper, by Joly et al. (2025) ‘Temperate grassland conversion to conifer forest destabilises mineral soil carbon stocks’, appears to suggest that the WCC does ‘not yet include an assessment of possible changes of soil C stocks following afforestation’.

Given that (according to the 14 July 2011 document) there was an apparent willingness to update the WCC in line with any research showing increases in soil carbon stock following planting (and apply this change at the first verification), are the WCC planning to update the WCC to account for long-term declines in soil carbon stocks post-planting, as several research papers demonstrate?

7). If the WCC is revised to account for long-term soil carbon losses post-planting, will this be applied to any existing projects? If so, which ones? If applied would this change occur to those projects awaiting all subsequent verifications over

8). Please can the WCC provide all information relating to discussions or correspondence relating to possible revisions to the WCC to account for long-term soil carbon changes post-planting for both mineral soils and organo-mineral soils This would be all correspondence with third parties and all internal correspondence with the WCC and Scottish Forestry.

9. Please can you provide the names and/or job titles of the staff with the WCC and Scottish Forestry who are responsible for proposing changes or revisions to the WCC, along with the names and job titles of staff with the WCC, Scottish Forestry and anyone else in the Scottish Government who are responsible for implementing or rejecting proposed changes or revisions to the WCC.

Response

I would like to make a request for review of the response I was provided by Scottish Forestry for EIR 2026/00513712 and the supplementary response 2026/00515414; both of these responses are dated 24 April 2026, and relate to the one request I made dated 26 March 2026.

A. In point 1, it was stated:

However, the same sentence says (for organo-mineral soils) ‘there can be subsequent gains to soil carbon as woodland grow and mature’. Please could you provide and identify the specific research source(s) that reaches this conclusion.

Your response has provided the name of a 159-page research paper (Morrison et al, 2012) and a book (Read DJ et al, 2009), which seems to be out of print and may not be available online.

Providing a reference or references to hundreds of pages of allegedly ‘relevant research’ does not in this case seem to be providing the requested information. I asked for the specific research source that shows gains to soil carbon occur on organo-mineral soils. This has so far not been provided. Please provide the specific paragraph or paragraphs and page or pages from what you claim to be ‘relevant research’ that you think will substantiate the claim made in respect of soil carbon increasing on organo-mineral soils.

Further to point 1, Scottish Forestry claim that Regulation 10(5)(c) of the EIRs applies to the withholding of the two documents listed in your response. This seems to be untrue; the Morrison et al (2012) paper (link below) is freely available online from the Forest Research website. Forest Research seems to make all its publications freely available online, which seems to be standard policy for Forest Research, an organisation that is funded by the taxpayer and has to meet transparency standards. https://www.forestresearch.gov.uk/publications/understanding-the-carbon-and-greenhouse-gas-balance-of-forests-in-britain/ 

The second document (Read DJ et al, 2009), was published by the UK Stationery Office, and the entire document (243 pages in length) is free to download (see link below), so it seems to be untrue that Regulation 10(5)(c) of the EIRs applies to the withholding of the two documents listed in your response. Given this document was used to ‘form part of the UK’s response to the Intergovernmental Panel on Climate Change 4th Assessment Report from 2007’, it seems even more odd that Regulation 10(5)(c) could apply to a publication commissioned by the taxpayer-funded Forestry Commission.

https://www.tsoshop.co.uk/product/9780114973513/Combating-Climate-Change-A-Role-For-UK-Forests-Main-Report-Paperback 

Even if these documents were not publicly available, due to copyright or other reasons, because I requested the specific source(s) of information, Scottish Forestry should provide the specific page numbers and paragraphs of the text within this allegedly ‘relevant research’ to support its assertions. Please can you now do this and provide the requested information (if it exists at all) from these documents.

B. In point 2, it was stated:
…please could you provide the research paper title(s) and author(s) of all research relating to potential post-planting soil carbon changes….

The link you have provided in your response (see below) seems to be a summary of some research projects:

https://www.forestresearch.gov.uk/research/soil-sustainability/woodland-creation-and-soil-carbon-and-nutrient-dynamics/

However, the list of research projects seems to be lacking in providing specific research titles and all their authors.

For example, under ‘Changes to C stocks in Scottish soils due to afforestation’ a very brief summary, research objectives, and results are outlined (with a contact), but the actual paper title, author(s), reference number (Forest Research may have project numbers) or date is not provided.

Under ‘Soils and the Woodland Carbon Code’, a sub heading ‘Results so far provides three links; two of these are links to the same page.

Given that my original request focussed on organo-mineral soils, please could you provide the author(s), for ‘Changes to C stocks in Scottish soils due to afforestation’ (and the title if this is different), with a suitable link, as you have not provided this.

C. For point 6, it was stated that

Research has shown that carbon continues to be lost from the soil for many years after planting for some sites, thus contradicting (a) the suggestion in the 14 July 2011 document that organo-mineral soils gain carbon over time after planting, and (b) any assumptions (potentially held by the WCC and others) that soil carbon in organo-mineral soils remain constant over time after planting.

Your response appears to have misinterpreted my request; I am already aware the Woodland Carbon Code accounts for soil carbon emissions after planting, but this is due to initial disturbance and ground preparation for planting. According to Joly et al (2025), the WCC ‘does not yet include an assessment of possible changes of soil C stocks following afforestation’. The point I am making is that research has shown soil carbon losses occur over decadal timescales, not due to ‘management practices that involve higher levels of soil carbon emissions’ as you infer. You state the woodland ‘does not achieve a positive carbon balance for 10 or 20 years or more’. The carbon balance presumably refers to both above and below ground carbon; that is a separate matter. I am referring specifically to carbon losses from the soil due to factors such as mycorrhizal activity and long-term soil changes, not carbon losses from initial mechanical disturbances.

As research is showing the WCC is underestimating long-term soil carbon losses on certain soil types, please could you provide a response to my original question; are the WCC planning to update the WCC to account for long-term declines in soil carbon stocks post-planting, as several research papers demonstrate?

Response to your review request

I have now completed my review of our response to your request 202600513712 under the Environmental Information (Scotland) Regulations 2004 (EIRs).

I have reviewed our original response and concluded that the original decision should be modified in order to provide more clarity on the information already provided.

Your initial questions in EIR request 202600513712 were:

1. The Woodland Carbon Code (WCC) version 3.0 (January 2026) provides links to a document titled ‘Soil Carbon and the Woodland Carbon Code’ (Vicky West, 14 July 2011, 10 pages).

This document claims on page 5 that:

Research recognises that there can be initial losses to soil carbon on organo-mineral soils, but that depending on the intensity of the ground preparation and ongoing management, there can be subsequent gains to soil carbon as woodlands grow and mature.

In respect of the above paragraph, it appears that the ‘initial losses’ are supposedly determined through a percentage loss of carbon from the soil due to disturbance resulting from forestry techniques such as hand turfing, mounding, ploughing and scarifying (as referred on pages 5-6).

However, the same sentence says (for organo-mineral soils) ‘there can be subsequent gains to soil carbon as woodlands grow and mature’. Please could you provide and/or identify the specific research source(s) that reaches this conclusion. Although the document has eight references (page 9), it is unclear if any of these items of research contains the assertion (and if this is substantiated) that ‘there can be subsequent gains to soil carbon as woodlands grow and mature’.

In our response to your request, you were provided with the names of the two relevant papers, these documents were subsequently withheld under Regulation 10(5)(c) of the Environmental Information (Scotland) Regulations 2004 (the EIRs) (Intellectual property rights). I am now overturning this exception and replacing it with Regulation 6(1)(b) of the Environmental Information (Scotland) Regulations 2004 (the EIRs) (Information already available).

I am now providing you with the links under Regulation 6(1)(b) and specific sources from these two relevant papers.

Morrison et al (2012) Understanding the Carbon and GHG balance of UK Forests, Forest Research fcrp018.pdf

Section 3.5 of this report refers to temporal changes in soil carbon under woodlands at the following places:

• P33, the text states “In forestry (assuming there are no disturbances), soil C generally accumulates during the forest stand development due to the input of woody and other debris. On the other hand, forest management could promote loss of soil C due to clearfelling and ground preparation for the second rotation (e.g. Zerva and Mencuccini, 2005b; see Sections 4.5 and 4.6). The timescale of this loss is significantly shorter than the timescale of the subsequent gain of soil C due to new plantation growth.”
• The text on p34 explores relevant experimental work in detail and describes soil carbon gains over time, including research carried out at Alice Holt from the mid-1990s which is compared to other studies.
• It may be helpful to consider the range of inputs and outputs in the woodland carbon balance, including the role of litter for example as an input to soil carbon (see p27). Figure 2.4b provides an overview of the carbon fluxes and pools in a woodland ecosystem.

Read DJ, Freer-Smith PH, Morison JL, Hanley N, West CC, Snowdon P (eds) (2009) Combating climate change – a role for UK forests. An assessment of the potential of the UK’s trees and woodlands to mitigate and adapt to climate change. The Stationery Office, Edinburgh Combating_Climate_Change_a_role_for_UK_forests_Main_Report.pdf

• Figure 3 in Chapter 3 on p28 provides a diagrammatic overview of the carbon fluxes (emissions and removals) in a forest ecosystem (in a similar way to the figure referred to in the 3rd bullet above). Hopefully, this establishes the principle that soil carbon stocks, and stocks in other forest carbon pools, change over time.
• Detail on soil carbon dynamics, including losses and gains over time, are described in section 3.4.5 on p35. Figure 3.10 on p37 provides a diagram to show changes over time.
• Further discussion of soil carbon gains and losses over time is provided in section 4.7.1 on p60
• Section 6.4 (p106) also discusses soil carbon changes over time, including significant soil carbon losses that can occur on organo-mineral soils after planting. It states the main determinants of soil carbon change under afforestation are soil type and the previous land-use. It should be noted that the Woodland Carbon Code (WCC) currently does not account for carbon gains on organo-mineral soils (although it does account for soil carbon losses) – it only accounts for carbon gains on mineral soils on sites that were formerly arable.
• Section 6.4 (p107) states that no studies had been published (at that time in 2009) on the afforestation of mineral soils in the UK although it refers to studies elsewhere that show gains on such sites. However, there has been subsequent research that covers mineral soils. Further details can be found here including ongoing work at WCC sites to assess soil carbon changes over time. This confirms that “Forests planted on mineral soils are generally accepted to result in increased soil carbon (C) content”.
• It should be noted that we aim to follow scientific evidence and consensus in the WCC’s approach to soil carbon. Individual papers can show contrasting results but changes in soil carbon over time are very context dependant, and the general trend in the evidence is that carbon increases over time particularly in mineral soils but also in organo-mineral soils (once emissions resulting from any soil disturbance at planting have ceased).

2. Page 5 of this same (14 July 2011) document states:

Further research in the next 2-3 years will allow us to develop more reliable figures for rates of soil carbon accumulation. Results of this research will be used in the next Woodland Carbon Code update on soil carbon. Projects will be able to update their soil carbon estimates at the first verification, based this research and update.

In respect of the ‘further research in the next 2-3 years’ being used to ‘develop more reliable figures for rates of soil carbon accumulation’, please could you provide the research paper title(s) and author(s) of all research relating to potential post-planting soil carbon changes, not just for the 2-3 years after July 2011, but up to the present day. The above sentence seems to make the presumption that soil carbon accumulates post-planting (presumably after allowing for carbon losses from initial disturbance). As this research may instead show soil carbon is lost post-planting (long after initial disturbances to soil through establishment preparation and planting), it appears Scottish Forestry/WCC might also hold research and/or information from July 2011 to the present day demonstrating that soil carbon is lost over the longer term, not just from initial disturbances to soil through preparation and planting. Please ensure these research paper titles and authors are also provided.

Note: when I refer to soil carbon losses over the longer term, I mean soil carbon losses that are not due to disturbance to the soil through establishment preparation and planting (such as hinge mounding or scarifying), but due to physical, biological and other changes occurring due to the introduction of trees to the soil, and the subsequent growth of these trees over the long term (years and decades)

Our response to this request was handled as a general correspondence and not under the Environmental Information (Scotland) Regulations 2004 (EIRs). Therefore, this question will be responded to as general correspondence on or before 28 May 2026 and will not be responded to as part of this EIR review.

6. Research has shown that carbon continues to be lost from the soil for many years after planting for some sites, thus contradicting (a) the suggestion in the 14 July 2011 document that organo-mineral soils gain carbon over time after planting, and (b) any assumptions (potentially held by the WCC and others) that soil carbon in organo-mineral soils remain constant over time after planting.

For example, a paper by Friggens et al. (2020) ‘Tree planting in organic soils does not result in net carbon sequestration on decadal timescales’, appears to demonstrate that soil carbon decreased significantly for some sites. Another paper, by Joly et al. (2025) ‘Temperate grassland conversion to conifer forest destabilises mineral soil carbon stocks’, appears to suggest that the WCC does ‘not yet include an assessment of possible changes of soil C stocks following afforestation’.

Given that (according to the 14 July 2011 document) there was an apparent willingness to update the WCC in line with any research showing increases in soil carbon stock following planting (and apply this change at the first verification), are the WCC planning to update the WCC to account for long-term declines in soil carbon stocks post-planting, as several research papers demonstrate?

You stated in your review request that our response appears to have misinterpreted your request.

We are now providing a further response to your request:

The question refers to “several research papers” that indicate long-term soil carbon losses post-planting but the Woodland Carbon Code’s treatment of soil carbon aims to follow scientific consensus. The findings of individual papers can be considered but require careful scrutiny due to them being very context-specific. This means that the WCC will follow balanced assessments of the evidence provided by Forest Research. Please note also that work to assess soils carbon stocks at WCC sites (see here) is providing further results that may potentially enable sufficient information to be collated to generate look up tables for soil carbon for the WCC.

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