Above-ground biomass and carbon sequestration in mangroves in the arid area of the northwest of Mexico: Bahía del Tóbari and Estero El Sargento, Sonora

Introduction: Mangroves are the largest carbon sinks and contribute to mitigate the effects of global climate change. Objective: To estimate the above-ground biomass (AB) of El Sargento estuary and Bahia del Tobari, to compare the carbon stocks between both places. Materials and methods: Measurements were taken from May 2014 to November 2015. The species were identified, and tree diameter, height and canopy cover were measured in 16 plots of 10 x 10 m. The AB was estimated with allometric equations and was related to the carbon content by the factor 0.5. The statistically significant differences between the carbon contents of both study sites were detected with the T test for independent samples. Results and discussion: The AB in El Sargento estuary was estimated between 108.1 and 316.78 Mg.ha(-1) with predominance of Laguncularia racemosa (L.) Gaertn (60 %); in Bahia del Tobari, the AB varied between 72.12 and 130 Mg.ha(-1), prevailing Avicennia germinans (L.) L. (83.4 %). In both sites Rhizophora mangle L. was found marginally. Total carbon storage was greater in El Sargento (with a range of 54.1 to 158.4 Mg C.ha(-1)) compared to Bahia del Tobari (36.1 to 65.5 Mg C.ha(-1)); the difference was statistically significant (F = 0.01; P = 0.02). Conclusion: The difference in the carbon reserves of the study sites is related to the good species development and diversity of a pristine environment (El Sargento), compared to another severely impacted environment (Bahia del Tobari).