Wetland Carbon Fluxes and Land Use Change Impacts in the Niger Delta Freshwater Swamps

Freshwater swamp forests in Nigeria's Niger Delta store substantial quantities of organic carbon in both vegetation and waterlogged peat soils, and their conversion to agriculture, aquaculture, or degradation through oil contamination releases stored carbon to the atmosphere while eliminating ongoing sequestration, with implications for Nigeria's climate commitments that remain poorly quantified in the South South geopolitical zone literature. This study measures carbon fluxes and estimates the land use change carbon emission impacts in Niger Delta freshwater swamps spanning Delta and Bayelsa States. Carbon stock measurements were conducted at 40 vegetation plots distributed across intact swamp forest, moderately degraded, severely degraded, and converted land use categories. Above and below-ground biomass inventories, litter carbon measurements, and peat depth and organic carbon content measurements were taken at each plot. Land use change areas between 2012 and 2022 were quantified from Sentinel-2 time-series classification to estimate total carbon emission from each transition category. Eddy covariance flux measurement data from a monitoring tower established at one intact swamp forest site provided a 12-month net ecosystem exchange baseline. Results indicate that intact freshwater swamp forests store a mean of 280 Mg C per hectare across above-ground, below-ground, and soil components, representing some of the highest tropical peatland carbon densities reported for West Africa. Carbon emissions from oil spill-driven swamp defoliation and conversion are estimated at 145 Mg CO2 equivalent per hectare on average. The study provides original quantitative evidence supporting the priority of Niger Delta swamp conservation in Nigeria's REDD-plus national programme. Keywords: wetland carbon, Niger Delta, freshwater swamp, land use change, South South Nigeria.