Analysis of biomass and carbon stock on mangrove forest ecosystem in coastal area of Purnama Subdistrict Dumai City Riau Province has been conducted in June-July 2013. The potencies of biomass, carbon stock and CO2 sequestration within undisturb (Station 1) and disturb (Station 2) mangrove forest area were compared. The results showed that in Station 1, the largest biomass and carbon stock pot…