Peacock, M 
ORCID: 0000-0002-3086-2854, Gauci, V, Baird, AJ, Burden, A, Chapman, PJ, Cumming, A, Evans, JG, Grayson, RP, Holden, J, Kaduk, J et al (show 7 more authors)
(2019)
The full carbon balance of a rewetted cropland fen and a conservation-managed fen.
AGRICULTURE ECOSYSTEMS & ENVIRONMENT, 269.
pp. 1-12.
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Abstract
On a global scale, the release of greenhouse gases (GHG) from peatland drainage and cultivation are believed to account for ∼5% of estimated anthropogenic GHG emissions. Drainage generally leads to peat subsidence and extensive soil loss, resulting in a diminishing store of soil carbon (C). This is a challenge for maintaining drainage-based agriculture, as such practices will eventually lead to the loss of organic soils that arable cultivation depends on. The conversion of croplands on peat to semi-natural grasslands, alongside raising water tables, is one possible way to reduce the loss of these valuable C stores. Here, we report the net ecosystem carbon balances (NECB) of two lowland peatlands in East Anglia, south-east UK. One site is a relic conservation-managed fen on deep peat, subject to active hydrological management to maintain water levels, and dominated by Cladium and Phragmites sedge and reed beds, whilst the other is a former cropland that has been converted to seasonally-inundated grazed grassland. Despite occasionally experiencing severe water table drawdown, the conservation-managed fen was a strong C sink of -104 g C m⁻² yr⁻¹. In contrast, the grassland was a C source of 133 g C m⁻² yr⁻¹, with gaseous carbon dioxide (CO₂) emissions being the main loss pathway, due to low water tables exposing the soil profile in summer. At each site, ditch emissions of CO₂ were moderately large (22 and 37 g C m⁻² yr⁻¹), whilst ditch methane (CH₄) emissions (0.2 and 1.8 g C m⁻² yr⁻¹) made a negligible contribution to the NECB, but are important when considering the ecosystem GHG balance in terms of CO₂ equivalents. Excluding dissolved inorganic carbon (DIC), fluvial C losses were 6 g C m⁻² yr⁻¹ for the conservation-managed fen and 12 g C m⁻² yr⁻¹ for the former cropland, and were dominated by dissolved organic carbon (DOC). The small fluvial C loss is the result of both sites being hydrologically isolated from the surrounding agricultural landscapes. Although the partially re-wetted cropland was still acting as a net C source, our estimates suggest that seasonal rewetting has reduced net annual C losses to ∼20% of their former cropland values. Maintaining high water tables year round would potentially further reduce C losses, and shallow inundation might allow the return of wetland species such as Phragmites and Typha, perhaps as floating rafts.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | Peatland, Net ecosystem carbon balance, Greenhouse gas, Dissolved organic carbon, Restoration, Drainage |
| Divisions: | Faculty of Science and Engineering > School of Environmental Sciences |
| Depositing User: | Symplectic Admin |
| Date Deposited: | 01 Aug 2022 14:52 |
| Last Modified: | 07 Nov 2023 05:31 |
| DOI: | 10.1016/j.agee.2018.09.020 |
| Related URLs: | |
| URI: | https://livrepository.liverpool.ac.uk/id/eprint/3160093 |
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