This Natural England Research Report reviews the scientific evidence base relating to carbon storage and sequestration by semi-natural habitats, in relation to their condition and/or management.
In this report, we review the scientific evidence base relating to carbon storage and sequestration by semi-natural habitats, in relation to their condition and/or management. This new report updates and expands previous work by Natural England on ‘Carbon storage by habitat’ published in 2012. We cover terrestrial, coastal and marine habitats, and the freshwater systems that connect them, in order to quantify their relative benefits for carbon management.
R Gregg, J. L. Elias, I Alonso, I.E. Crosher and P Muto and M.D. Morecroft (2021) Carbon storage and sequestration by habitat: a review of the evidence (second edition) Natural England Research Report NERR094. Natural England, York.
Figure 2 from this report and a photo of Bursdon Moor SSSI by Roger Kidd https://www.geograph.org.uk/photo/4928490
Opportunities for Nature-based solutions (NbS) to deliver for climate change mitigation
NbS is a key concept for tackling the climate and biodiversity crises. A joined-up approach that addresses both climate change and biodiversity decline together is the only realistic way of meeting the multiple demands on our environment. Within this report we identify where creation, restoration and improved management of natural habitats can contribute to delivery of the net zero target. Nevertheless, there is a need to be realistic: it is not possible to offset anything close to current UK emissions across the different sectors of the economy through better environmental management alone. Deep cuts in emissions across all sectors is required with NbS playing an important role in mitigating the residual, hard-to-eliminate emissions.
The success of NbS for climate is dependent on location. It is important to be rigorous in assessing how much difference any change in land use or management will make to biodiversity and climate in a particular place. If NbS is to make a significant contribution to achieving net zero by 2050, implementation needs to increase significantly and immediately. For many habitats there is a lag between instigating creation and restoration approaches and seeing the benefits in terms of carbon.
Nature-based solutions can deliver for climate adaptation, as well as mitigation, and future change must be considered. Nature-based solutions should be designed, managed and evaluated to ensure that they will continue to be effective in a future which is warmer and subject to changes in rainfall, including more extreme events such as droughts and floods.
By looking across a range of habitats, and considering biodiversity alongside climate change mitigation, we identify the following key principles from our assessment:
1. Protect and restore peatlands. Peatlands are our largest natural carbon stores and it is important to slow and eventually halt greenhouse gas emissions, including through raising water tables, stopping burning and removing planted trees.
2. Create new native broadleaved woodlands. Native woodland is an effective carbon sink and over much of England can deliver comparable carbon uptake to non-native species and provide more benefits for biodiversity. Growing the right trees in the right place is however critical to maximise these benefits.
3. Protect and restore natural coastal processes. This allows habitats, such as saltmarsh, to maintain themselves and re-establish inland as the sea level rises, and to sequester and store carbon. It is also an important and urgent aspect of climate change adaptation. Active intervention to will be necessary to restore some habitats, such as sea grass.
4. Protect existing semi-natural habitats. Most of England has been intensively managed for a long time and semi-natural habitats, of all types, are rare fragments containing many of our native species that are not found elsewhere. Many of these, including grasslands and heathlands, also store appreciable amounts of carbon in their vegetation, undisturbed soils and sediments.
5. Target incentives for NbS to places where they can have most benefit. Different approaches work better in different places and it is important to maximise synergies and minimise tradeoffs if we are to deliver net zero ambitions at the same time as restoring biodiversity and meeting the needs of people. Decisions about NbS need to consider the wider context of land use and management and the need to maintain, and where possible increase, domestic food and timber production in ways which do not lead to increased emissions either in the UK or overseas.
6. Integrate NbS for climate into landscapes which are primarily devoted to agriculture or production forestry. To meet the scale of change required in greenhouse gas emissions, there is a need to take land out of agriculture, particularly for woodland creation and peatland restoration. Actions such as hedgerow planting, good soil management and innovative agricultural approaches, such as paludiculture, can also contribute whilst enabling agricultural production to continue. Within production forest biodiversity can be supported by including broadleaved trees and appropriate management of forest rides and edges.
7 Carry out research and monitoring to fill evidence gaps. There are still large knowledge gaps for many habitats. For example, there is significant potential to increase carbon stocks for coastal and marine habitats, but we lack evidence in the English or UK context. Across all habitats, the carbon content of soils, sediments and vegetation, and ecosystem carbon fluxes are rarely measured. Even the depth of soil is rarely monitored. The role that freshwater habitats can play in climate change mitigation is also an understudied area.
8. Ensure mitigation and adaptation to climate change are planned together. This is important to ensure the durability of solutions for carbon sequestration and storage and to promote synergies rather than conflicts between objectives. We should look for multifunctional and integrated opportunities when planning our responses to the climate and biodiversity crises.