Role of Avicennia marina (Forssk.) Vierh. of South Sinai, Egypt in Atmospheric CO2 Sequestration

This study focused on valuation of the mangrove (Avicennia marina) sediments organic carbon stock for naturally occurring mature mangrove in all defined habitat types (Intertidal, Shoreline, Salt Plains) distributed along Gulf of Aqaba and the Red Sea in two marine protected areas (Nabq and Ras Mohammed) in South Sinai, Egypt, results were compared with soil organic carbon in sediments from 10 years old planted mangrove, non-mangrove mud flats and the hypersaline ecosystem of Salt Lake in Ras Mohammed National Park. Furthermore, the study estimated the potential of these ecosystems in the process of atmospheric CO2 sequestration using the low-temperature loss on ignition (oC 375/17 hrs. ), sediment samples were also analyzed for dry bulk density (DBD) and percentage of soil organic carbon (SOC) at a depth interval 10 cm to the maximum reached depth. Change in mean DBD of intertidal mangrove soil was increasing gradually passing from uppermost layer to deeper layer but converse pattern obtained in the hypersaline ecosystem while in the rest of studied habitats change in soil DBD with depth did not follow a distinct pattern. SOC for the six studied habitats showed the following descending order 34.4, 25.7, 14.51, 7.24, 5.74 and 3.58 g C kg-1 for intertidal mangrove, hypersaline ecosystem, salt plain mangrove, shoreline mangrove, planted mangrove and non-mangrove mud flats respectively. Only 10 years old mangroves had a carbon stock in sediments equal 44.19 % of these mature intertidal mangrove so mangrove plantation is an efficient action for mitigation of climate change especially if it is conducted on previously depleted mangrove sites (restoration) than transplantation in non-mangrove sits. Mangrove of intertidal habitat is contributed with 95% of carbon sequestration process of Sinai mangrove, the overall carbon sequestration potential of Sinai and Egypt mangroves are 116.89 and 1207.5 t C year-1 respectively considering that all Egypt's mangroves have similar sequestration potential to studied Sinai mangrove.