Mangrove biomass and carbon storage in India: Implications for blue carbon potential

Mangroves are highly productive coastal forests that store large amounts of carbon in their biomass (4.4 to 11.7 Pg of carbon). Research on mangrove biomass carbon in India remains limited and uneven, with key parameters often unreported, resulting in fragmented estimates that limit their applicability in carbon accounting and climate planning. This review synthesizes field-based data on above-ground biomass (AGB), below-ground biomass (BGB), and associated biomass carbon stocks across major Indian mangrove systems, encompassing deltaic, estuarine, coastal, and island environments, and harmonizes published datasets using IPCC-consistent methodologies. Across Indian mangroves, AGB spans nearly two orders of magnitude, ranging from low values in stunted, hypersaline, and anthropogenically disturbed stands to exceptionally high values in mature forests, with BGB commonly contributing 25-40% of above-ground biomass. Deltaic and island systems, including the Sundarbans, Bhitarkanika, and the Andaman Islands, consistently emerge as biomass and carbon hotspots, whereas arid and highly stressed west-coast mangroves exhibit substantially lower biomass carbon densities. Synthesis of available data indicates that salinity exerts a weak influence on above-ground biomass but strongly regulates below-ground biomass allocation, reflecting adaptive shifts toward increased root investment under salinity stress, while a strong coupling between AGB and BGB across sites demonstrates coordinated whole-plant biomass allocation consistent with allometric scaling theory. By integrating above- and below-ground biomass components and expressing biomass carbon stocks in CO2-equivalent terms, this review highlights the spatial heterogeneity in Indian mangrove biomass carbon storage and the importance of depth-inclusive, field-validated biomass accounting for blue-carbon strategies, national greenhouse gas inventories, and biomass-focused decarbonization pathways in India.