Soil and Vegetative Carbon Sequestration in Khuran Estuary Mangroves, Strait of Hormoz, During the Last 18 Centuries

The present paper, for the first time, estimates the amount of soil and vegetative blue carbon (C) sequestered in Khuran mangrove, Iran’s largest mangrove forest along the Persian Gulf coasts. Cores were retrieved down to parental materials in 32 stations to achieve whole-soil C stock. A radiocarbon dating was also used to estimate sediment accretion and C sequestration rates during the last 18 centuries. Results indicated that soils and mangrove trees of the Khuran store a total of 16.79 Tg C (equivalent to ~ 60 Tg of CO 2 ), 98.8% of which (16.59 Tg C) is sequestered in mangrove soils. During the last couple of thousand years, 8967 Mg C year −1 (one Mg C ha −1 year −1 ) has been stored in mangrove soils of the area. Mean whole-soil C stock in Khamir and Qeshm is 1076 and 2134 Mg C ha −1 , respectively. A total of 5181 Gg C and 201 Gg C is stored in the top 1 m of soil and mangrove trees, respectively, 76% of which is sequestered in QM. Our results also indicate that mangroves located in desert and dryland coasts can store comparable quantities of belowground C than their tropical counterparts. High phytoplankton concentration and accreting mangrove high organic C content soils on their own accumulated peat in response to sea-level rise have possibly caused Khuran desert mangroves to store large amounts of C in their sediments. Our estimates suggest that probable complete deforestation of Khuran mangrove could lead to 8.14 Tg CO 2 equivalent emissions.