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- PublicationCarbon and climate implications of rewetting a raised bog in IrelandPeatland rewetting has been proposed as a vital climate change mitigation tool to reduce greenhouse gas emissions and to generate suitable conditions for the return of carbon (C) sequestration. In this study, we present annual C balances for a 5-year period at a rewetted peatland in Ireland (rewetted at the start of the study) and compare the results with an adjacent drained area (represents business-as-usual). Hydrological modelling of the 230-hectare site was carried out to determine the likely ecotopes (vegetation communities) that will develop post-rewetting and was used to inform a radiative forcing modelling exercise to determine the climate impacts of rewetting this peatland under five high-priority scenarios (SSP1-1.9, SS1-2.6, SSP2-4.5, SSP3-7.0 and SSP5-8.5). The drained area (marginal ecotope) was a net C source throughout the study and emitted 157 ± 25.5 g C m−2 year−1. In contrast, the rewetted area (sub-central ecotope) was a net C sink of 78.0 ± 37.6 g C m−2 year−1, despite relatively large annual methane emissions post-rewetting (average 19.3 ± 5.2 g C m−2 year−1). Hydrological modelling predicted the development of three key ecotopes at the site, with the sub-central ecotope predicted to cover 24% of the site, the sub-marginal predicted to cover 59% and the marginal predicted to cover 16%. Using these areal estimates, our radiative forcing modelling projects that under the SSP1-1.9 scenario, the site will have a warming effect on the climate until 2085 but will then have a strong cooling impact. In contrast, our modelling exercise shows that the site will never have a cooling impact under the SSP5-8.5 scenario. Our results confirm the importance of rapid rewetting of drained peatland sites to (a) achieve strong C emissions reductions, (b) establish optimal conditions for C sequestration and (c) set the site on a climate cooling trajectory.
242Scopus© Citations 11
- PublicationRewetting degraded peatlands for climate and biodiversity benefits: Results from two raised bogsGlobally, peatlands are under threat from a range of land use related factors that have a significant impact on the provision of ecosystem services, such as biodiversity and carbon (C) sequestration/storage. In Ireland, approximately 84% of raised bogs (a priority habitat listed in Annex I of the EU Habitats Directive) have been affected by peat extraction. While restoration implies the return of ecosystem services that were characteristic of the pre-disturbed ecosystem, achieving this goal is often a challenge in degraded peatlands as post-drainage conditions vary considerably between sites. Here, we present multi-year greenhouse gas (GHG) and vegetation dynamics data from two former raised bogs in Ireland that were drained and either industrially extracted (milled) or cut on the margins for domestic use and subsequently rewetted (with no further management). When upscaled to the ecosystem level, the rewetted nutrient poor domestic cutover peatland was a net sink of carbon dioxide (CO 2 ) (−49 ± 66 g C m −2 yr −1 ) and a source of methane (CH 4 ) (19.7 ± 5 g C m −2 yr −1 ), while the nutrient rich industrial cutaway was a net source of CO 2 (0.66 ± 168 g C m −2 yr −1 ) and CH 4 (5.0 ± 2.2 g C m −2 yr −1 ). The rewetted domestic cutover site exhibited the expected range of micro-habitats and species composition found in natural (non-degraded) counterparts. In contrast, despite successful rewetting, the industrially extracted peatland did not exhibit typical raised bog flora. This study demonstrated that environmental and management variables can influence species composition and, therefore, the regeneration of species typical of natural sites, and has highlighted the climate benefits from rewetting degraded peatlands in terms of reduced GHG emissions. However, rewetting of degraded peatlands is a major challenge and in some cases reintroduction of bryophytes typical of natural raised bogs may be more difficult than the achievement of proper GHG emission savings.
595Scopus© Citations 75