Quantifying the Blue Carbon Sink Capacity of Niger Delta Mangroves Under Degradation and Restoration Scenarios

The Niger Delta contains one of the largest contiguous mangrove ecosystems in Africa, representing a potentially significant blue carbon sink in Nigeria's greenhouse gas inventory, yet quantification of this sink under realistic degradation and restoration trajectories has remained methodologically fraught and empirically incomplete. This dissertation provides the most comprehensive quantification to date of the blue carbon sink capacity of Niger Delta mangroves by integrating field-based carbon stock inventories, eddy covariance flux tower measurements, sediment core palaeoecological analysis, and scenario-based carbon flux modelling. An intensive field campaign spanning three years across 48 inventory plots in intact, degraded, and early restoration mangrove sites in Bayelsa, Rivers, and Delta States determines above-ground biomass, below-ground biomass, and depth-resolved soil organic carbon stocks to two metres depth. Eddy covariance towers installed at two representative sites measure net ecosystem carbon exchange at half-hourly resolution across seasonal cycles. Sediment cores provide 200-year records of carbon accumulation rates determined through 210Pb and 14C dating, revealing the trajectory of carbon sink function prior to petroleum industry onset. A spatially explicit carbon balance model driven by mangrove area change projections from a land use change model under three development scenarios (business as usual, moderate conservation, aggressive restoration) projects the Niger Delta mangrove carbon balance to 2050. The dissertation advances blue carbon science by demonstrating the critical role of hydrological connectivity in controlling soil carbon preservation efficiency and providing the first empirical eddy covariance measurements of mangrove carbon exchange in Nigeria. Keywords: blue carbon, Niger Delta mangroves, eddy covariance, carbon sequestration, restoration scenarios