Mangroves cover less than 1 percent of the world's tropical coastline. They punch far above their weight.Per unit area, mangrove forests sequester carbon at two to four times the rate of tropical rainforests. They store up to five times more carbon per hectare than inland tropical forests do, and they store most of it underground, in the dense, waterlogged sediment of their root systems where decomposition almost stops. A hectare of mangrove forest may hold as much carbon in its soil as a hectar