Blue-Carbon Stocks and Coastal-Protection Values of West and Central African Mangroves: A Systematic Review Protocol

This systematic review synthesises quantitative evidence on carbon stocks and coastal-protection values of mangrove ecosystems in West and Central Africa (Mauritania to Angola), with tropical Atlantic and global comparators for benchmarking. Three questions structure the review. RQ-A: what total ecosystem carbon stocks and component pools (above-ground biomass, below-ground biomass, soil) are reported for West and Central African mangroves, and how do these vary with geomorphic setting, canopy height, and degradation status? RQ-B: what coastal-protection values have been quantified for mangroves in comparable settings, by what method, and with what data requirements? RQ-C: where are the geographic and methodological gaps in the West African evidence base, and what does this imply for national-scale carbon accounting in Liberia? The review supports doctoral research on blue-carbon accounting and coastal nature-based solutions in data-poor coastal nations. Existing regional evidence is dominated by a small number of stand-level studies insufficient to stratify a national estimate, so mapping the absence of evidence — by country, by carbon pool measured, and by soil-core depth — is treated as a primary output rather than a limitation. Extracted carbon densities with stratum-level uncertainty feed directly into a Monte Carlo simulation of national carbon stock. Searches cover Scopus, Web of Science Core Collection, ScienceDirect, AGRIS and African Journals Online, with Google Scholar and targeted institutional sources used for grey-literature capture. Records in English, French and Portuguese are eligible; the latter two are essential given the Lusophone and Francophone literature on Guinea-Bissau, Senegal, Guinea and Gabon. Grey literature is admitted only where it meets a stated quality gate and is flagged for sensitivity analysis. Screening proceeds in three stages against pre-specified criteria, with a random 20% double-screened at each stage, agreement reported as Cohen's κ, and a threshold of κ ≥ 0.70. Data are extracted one row per stand rather than per paper. Synthesis is by random-effects meta-analysis of carbon density by stratum, with an evidence-gap map by country, pool and method. Reporting follows PRISMA 2020.