RT Journal Article
SR Electronic
T1 Rapid carbon accumulation at a saltmarsh restored by managed realignment far exceeds carbon emitted in site construction
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 2021.10.12.464124
DO 10.1101/2021.10.12.464124
A1 Hannah L. Mossman
A1 Nigel Pontee
A1 Katie Born
A1 Peter J. Lawrence
A1 Stuart Rae
A1 James Scott
A1 Beatriz Serato
A1 Robert B. Sparkes
A1 Martin J.P. Sullivan
A1 Rachel M. Dunk
YR 2021
UL http://biorxiv.org/content/early/2021/10/12/2021.10.12.464124.abstract
AB Increasing attention is being paid to the carbon sequestration and storage services provided by coastal blue carbon ecosystems such as saltmarshes. Sites restored by managed realignment, where existing sea walls are breached to reinstate tidal inundation to the land behind, have considerable potential to accumulate carbon through deposition of sediment brought in by the tide and burial of vegetation in the site. While this potential has been recognised, it is not yet a common motivating factor for saltmarsh restoration, partly due to uncertainties about the rate of carbon accumulation and how this balances against the greenhouse gases emitted during site construction. We use a combination of field measurements over four years and remote sensing to quantify carbon accumulation at a large managed realignment site, Steart Marshes, UK. Sediment accumulated rapidly at Steart Marshes (mean of 75 mm yr-1) and had a high carbon content (4.4% total carbon, 2.2% total organic carbon), resulting in carbon accumulation of 36.6 t ha-1 yr-1 total carbon (19.4 t ha- 1 yr-1 total organic carbon). This rate of carbon accumulation is an order of magnitude higher than reported in many other restored saltmarshes, and is higher although more similar to values previously reported from another hypertidal system (Bay of Fundy, Canada). The estimated carbon emissions associated with the construction of the site were ∼2-4% of the observed carbon accumulation during the study period, supporting the view that managed realignment projects in such settings are likely to have significant carbon accumulation benefits. We outline further considerations that are needed to move towards a full carbon budget for saltmarsh restoration.Competing Interest StatementThe authors have declared no competing interest.