The surface sediment carbon content of a north norfolk saltmarsh
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Carbon sequestration is an important aspect of mitigating climate change and its detrimental environmental and economic effects. Vegetative ecosystems such as rainforests are often praised for their ability to sequester carbon through photosynthesis, however more efficient systems for sequestering carbon such as saltmarshes are often overlooked. Carbon storage was investigated in the developing salt marsh habitats of Holkham Bay, part of the Holkham National Nature Reserve in Norfolk, England between 31/07/2017 and 03/08/2017. This was done to assess the quantity of carbon that may be lost to rising sea levels associated with climate change and be released as CO2, which contributes to the greenhouse effect. Qualitative analyses of vegetation type and sediment texture were carried out using quadrat sampling (n = 70) and sediment cores (n = 35). Quantitative analysis of sediment carbon stock was carried out through loss on ignition. Carbon stock of the salt marsh was graphically represented using GIS mapping and an attempt was made to estimate the total carbon stock of the top 10 cm of the saltmarsh sediments. Measured values of carbon stocks at Holkham were compared with predicted values of carbon stock obtained using the Salt Marsh Carbon Stock Predictor tool. Significant differences in carbon stock between clay and sandy sediments were observed (p < 0.001), whilst vegetation communities showed no statistically significant difference in relation to carbon stock (p > 0.05). Estimates of carbon stock across the marsh (0.43 Km2) stand at 454-444 tonnes of carbon. Measured values of carbon stock were on average 14.18 Tonnes per Hectare lower than those predicted and are potentially due to marsh immaturity. Frequent anthropogenic disturbance at Holkham may be causing a reduction in carbon accumulation by the marsh vegetation. This study shows that substantial quantities of carbon could be lost from Holkham saltmarshes and indicates that larger marshes on the North Norfolk coastline may be substantially larger sinks of carbon, thus requiring continued protection and monitoring.
van Ree, R. (2019) 'The surface sediment carbon content of a north norfolk saltmarsh', The Plymouth Student Scientist, 12(1), p. 50-62.