His comments come on a day marking the first anniversary of a project to protect all of nation's mangroves.
As well as storing carbon, the forests provide habitat for fish and protect communities from tsunamis and cyclones.
Also on Tuesday - World Mangrove Day - Sri Lanka's president will open the world's first mangrove museum.
The museum will act as a hub for conservation training for adults, and educating children about the value of mangroves. It is estimated that 20,000 pupils will visit the museum in the first year.