E-Thesis 706 views 203 downloads
Holocene Carbon Accumulation, Wetness Shifts and Fire History at Three Threatened Peatlands in Carmarthenshire, SW Wales, UK / KRISTY HOLDER
Swansea University Author: KRISTY HOLDER
DOI (Published version): 10.23889/SUthesis.59169
Abstract
This project studies three peatlands in Carmarthenshire, SW Wales, UK (Figyn Common, Pyllau Cochion and Mynydd Bach) that are threatened by the impacts of continued human interference and projected climate change. The threat that human and climatic forces pose on peatland carbon storage has become a...
| Published: |
Swansea
2022
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| Institution: | Swansea University |
| Degree level: | Doctoral |
| Degree name: | Ph.D |
| Supervisor: | Davies, Siwan |
| URI: | https://cronfa.swan.ac.uk/Record/cronfa59169 |
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| Abstract: |
This project studies three peatlands in Carmarthenshire, SW Wales, UK (Figyn Common, Pyllau Cochion and Mynydd Bach) that are threatened by the impacts of continued human interference and projected climate change. The threat that human and climatic forces pose on peatland carbon storage has become a significant global concern in the fight against greenhouse gas climate forcing. A record of their Holocene environmental and developmental history is obtained via a multi-proxy analysis, including carbon:nitrogen ratio (C:N), humification, charcoal and carbon accumulation. Potential drivers of developmental change and temporal carbon accumulation are also explored. Fen peat inception occurred at ca. 10800, ca. 9730 and ca. 7960 cal yrs. BP at Figyn Common, Pyllau Cochion and Mynydd Bach (respectively). The fen to bog transition (FBT) is dated to ca. 5120 cal yrs. BP at Pyllau Cochion and ca. 4480 cal yrs. BP at Figyn Common. The FBT does not take place at Mynydd Bach. Evidence of regional wet shifts during the late Holocene is found at ca. 2000 and ca. 850 cal yrs. BP and a dry shift is detected at ca. 2400 cal yrs. BP. All three sites demonstrate evidence of burning through the Mesolithic period and on-site burning increases at all sites after ca. 4500 cal yrs. BP. At Mynydd Bach, fire activity is linked to Bronze Age ritual practices. Long-term Apparent Rates of Carbon Accumulation (LARCA) for the three sites are 23.71, 13.09 and 42.55 g C m -2 yr -1 for Pyllau Cochion, Mynydd Bach, and Figyn Common (respectively). Carbon accumulation is high in the early Holocene, likely in response to the faster accumulation rates associated with early fen stages. However, in contrast to other northern peatlands carbon accumulation is lower during the Holocene Thermal Maximum and higher in the late Holocene when neoglacial cooling persisted. This is most likely because they sit close to the bioclimatic threshold of peatland formation in a UK context. Furthermore, an association between shorter-term wet shifts and higher carbon accumulation is found at several points in the Pyllau Cochion and Figyn Common record. The findings imply that the sites accumulate more carbon during wetter/cooler conditions and less when it is warmer/drier. Therefore, it is likely that they will experience reductions in carbon accumulation in response to projected warming during the 21st century. This adds support to the widely reported theory in the literature that peripheral peatlands will be the first to see losses in their carbon sequestration capacity because of predicted warming. This work contributes to the public understanding of the environmental history of these peatlands and the results provide valuable insight for conservation and future management strategies along with an assessment of carbon projections. |
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| Item Description: |
A selection of third party content is redacted or is partially redacted from this thesis due to copyright restrictions. |
| Keywords: |
Peatland, carbon accumulation, Holocene, fire history, wetness shifts |
| College: |
Faculty of Science and Engineering |