7. CO₂ Fluxes in Mangrove Ecosystems

Mangroves have long been recognized as a potential sink of carbon owing to their high productivity and carbon sequestration potential. The short term CO₂ dynamics of mangroves are often put under lenses to examine their potential to combat the human induced CO₂ emission. Mainly three types of CO₂ fluxes take place within a mangrove ecosystem namely (i) atmosphere-biosphere CO₂ exchange, (ii) soil CO₂ efflux and (iii) air-water CO₂ flux. In this chapter, we have compiled all types of the CO₂ flux data from mangrove ecosystems with special emphasis on the Sundarban, the world’s largest mangrove forest and analyzed the regulating factors of these fluxes. Summarizing all the studies, it can be inferred that the terrestrial compartments of mangroves acts as net sink for CO₂, though the soil continually emit CO₂ (apart from few exceptions). Almost all the mangrove surrounding waters act as source of CO₂, however, the magnitude of air-water CO₂ fluxes are much less than the inward fluxes of CO₂ towards the canopy, hence the ecosystem as a whole acts as a net sink for CO₂. Light conditions, air temperature, salinity, tidal cycle and so forth are mainly found to regulate the atmosphere-biosphere CO₂ flux, whereas, soil temperature, moisture and waterlogging are the principal factors regulating the soil CO₂fluxes. In case of air-water fluxes, the main governing factors are the variation in salinity, pore-water flushing during ebb tide and wind speed.