Although we think of forests as trees on land, some of the most important trees grow in water, or more precisely, marshland. Mangrove forests, like this one in Saloum Delta National Park in Senegal, are vital components of the world"s coastal ecosystems. Mangroves survive where no other trees can, in salty, low-oxygen coastal waters exposed to tides and storms. They grow up to 30 feet high primarily in tropical and subtropical regions and are able to store vast amounts of carbon, making them crucial to moderating our climate. Mangroves also act as nurseries for fish and aquatic life. And with their complex, interwoven root systems, they protect coastlines from erosion. Today we join the UN in shining a light on the necessity and fragility of mangroves: July 26 is the International Day for the Conservation of the Mangrove Ecosystem.