Mapping and Quantification of Carbon Stocks in Mangrove Forests of the Niger Delta Using Remote Sensing

Mangrove forests in the Niger Delta store substantial above-ground and below-ground carbon stocks that are threatened by oil pollution, logging, and climate-driven sea level change, yet accurate spatial carbon stock estimates remain scarce for the Nigerian mangrove estate. This study maps mangrove extent and estimates carbon stocks in the Niger Delta mangrove zone across Rivers, Delta, and Bayelsa States using a combined remote sensing and field measurement approach. Mangrove canopy cover and structure are characterised from Sentinel-2 spectral indices and ALOS PALSAR L-band SAR backscatter, which is sensitive to forest biomass at canopy heights relevant to mangrove stands. Allometric equation-based above-ground biomass estimates are derived from field-measured stem diameter and height data collected at fifty randomised plots, and conversion factors from recent literature are applied to estimate total carbon stocks per plot. A regression model linking field biomass measurements to SAR backscatter and spectral index predictor variables is developed and applied spatially to map above-ground carbon density across the full mangrove extent. Results indicate a total above-ground carbon stock of approximately 18.4 million tonnes for the mapped Niger Delta mangrove area, with the most carbon-dense stands located in less disturbed areas of southern Bayelsa. The study fills a critical evidence gap and provides spatial carbon stock data relevant to REDD+ programme design under the Nigerian Carbon Market Framework. Keywords: mangrove carbon stocks, remote sensing, SAR, Niger Delta, REDD+.