For years, scientists have known that mangrove forests are incredibly productive ecosystems. A single acre of mangroves can drop 2-3 tons of leaves per year! And that’s just one acre. Of course, those leaves are being replaced at a similar rate, so mangrove forests are always green and lush.
Like other plants, mangroves take in carbon dioxide from the air as they photosynthesize. They use this carbon dioxide to produce more leaves. As a result, this carbon gets “locked in” – it is no longer in the air. This is why plant communities like forests and grasslands are called “carbon sinks.” Just like a sink in a kitchen, forests hold the carbon in a form that is not harmful to our planet. But that’s not the whole story, because the sink leaks.
As leaves drop from trees, they decompose, slowly draining that trapped carbon back into the atmosphere. In mangrove forests, those leaves drop into the water. Lower oxygen levels in that water means that the leaves decay more slowly than they would in air. They also serve as a primary food source for a variety of animals like worms, shrimp, fish and crabs. The carbon that these animals consume remains trapped for a longer period of time than it would if the leaves were to decompose in the air. Those animals transport that carbon to deeper water, either directly, or by being eaten by animals that live in deeper waters. When they die, they sink to the bottom where their carbon remains trapped indefinitely.
Researchers at the National Park Service’s South Florida Natural Resource Center have found that mangrove forests have 2 to 3 times the net carbon trapping ability of many other forests, making them an important player in the fight against climate change.