How will projected sea-level rise affect carbon storage in floodplain fens?
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Floodplain fens represent an important component of the global carbon cycle through their role in carbon sequestration. Peat development depends upon rate of production exceeding rate of decomposition, yet there is little understanding of the effects of sea-level rise on these processes in lowland environments. This thesis investigates the impacts of projected sea-level rise from climate change on carbon storage in floodplain fens, using a combination of field, laboratory and simulation modelling techniques. A gradient of saline influence was determined for the Broads, UK, based on analysis of water chemistry and published water level data, allowing for the application of a space-for-time substitution technique. Increased water level had a positive effect on above-ground production of Phragmites australis (cav.) Trin. Ex Steud. (1841) - perhaps because water stress limits important photosynthetic processes. An increase in salinity had a negative effect on the growth of P. australis, probably due in part to osmotic stress. Previous management practice significantly impacted on production – as uncut vegetation became less productive with time. There was evidence to suggest that sea-level rise may lead to faster decay rates, but this will be partially offset by litter quality. Saline influenced sites had lower carbon accumulation potentials. Radiometric dating confirmed that these sites have lower carbon sequestration rates - probably as a result of increased mineral deposition in floodwaters. Carbon stock ranged between 33 and 144 kt C but depended greatly on peat depth and bulk density. Results from both field data and the model indicated that peat accretion in the Broads would not offset projected sea-level rise. Floodplain fen development under the influence of sea-level rise will be dependent on the majority of assimilate being allocated to above-ground vegetation.
AuthorsWebster, Eleanor Jane
- Theses