Lowland peatland systems in England and Wales – evaluating greenhouse gas fluxes and carbon balances - SP1210

Peatlands provide the United Kingdom's largest terrestrial carbon store, and in good condition can sequester carbon dioxide from the atmosphere into the accumulating peat, helping to mitigate against climate change. However, the disturbance or inappropriate management of this store can release large quantities of greenhouse gases to the atmosphere. Within the UK, land-use impacts on peats are disproportionately concentrated on lowland bogs and fens, due to their high agricultural value (in regions such as the Fens of East Anglia), their relative accessibility compared to upland blanket bogs, and their widespread historic exploitation for peat extraction. As a result, it has been estimated that over half of all greenhouse gas emissions from UK peatlands are derived from degraded lowland peats in England and Wales.

However, although it is clear that peat is being lost from many areas, direct measurements of greenhouse gas emissions from lowland peats are sparse. This project will provide the first full carbon and greenhouse gas budgets for lowland peats across England and Wales. We will monitor a range of sites spanning a range of land-use, from near-pristine bogs and fens to sites affected by drainage, nutrient enrichment, peat extraction, intensive grazing and arable agriculture. We will also consider sites that have previously been converted back from intensive land-use to lower-intensity forms of management.

To quantify the greenhouse gas budget for each site we will measure the exchange of carbon dioxide between the peatland and the atmosphere, together with emissions of the other major greenhouse gases, methane and nitrous oxide. We will also measure other pathways of carbon loss from the peat, in particular dissolved and particulate carbon loss in drainage water. These measurements will be supported by the detailed characterisation of site conditions and management at each site, so that results can be scaled up to the wider area of lowland peat. Results will be used to develop 'emission factors' for each peat type under a range of management activities, which can be included in the UK's 'Land Use, Land Use Change and Forestry' greenhouse gas accounting inventory. The results should improve the evidence base on which national policymakers and local land-managers make decisions on the management of lowland peats, allowing them to balance the role of peatlands in regulating greenhouse gas emissions against the many other 'ecosystem services' they provide, such as food production, floodwater regulation, places for recreation and habitats for rare species.

We will undertake this research in close collaboration with a range of landowners and stakeholders including farmers, conservation organisations and peat extraction companies, and ensure that the knowledge obtained from the research is communicated with the wider community of stakeholders with an interest in the future of Britain's lowland peatlands.

Objective

The project will have the following key objectives.

1) To systematically review the knowledge base on carbon (C) and greenhouse gas (GHG) fluxes in lowland peats as a function of land-use/management and peat type

2) To finalise, in discussion with Defra, a network of lowland peat C/GHG monitoring sites which reflect the distribution of peatland types and key land-use/management factors affecting GHG fluxes within England and Wales

3) To establish instrumentation and initiate monitoring of the full C/GHG balance at all sites according to standardised protocols

4) To collect three full years of C/GHG flux data for all selected measurement sites

5) To derive, for the first time, appropriate emission factors for CO2, CH4 and N2O as a function of typology and management for lowland peats across England and Wales

6) To re-evaluate the knowledge base on C/GHG balances of UK lowland peats as a function of management, based on the results of the measurement programme and an update available evidence from other sources

7) To upscale these results to provide the first estimate of the net C and GHG budgets of lowland peats across England and Wales, and to compare these estimates (on both a per unit area and total basis) to comparable data from upland peats.