…a new book on an old subject

The new World Atlas of Mangroves appeared a couple of weeks ago.  The Atlas is the first global look at mangroves in more than ten years, and the most detailed so far.  Advances in satellite observation allowed the map-makers to show not only where the mangroves are, but where they have been.  It’s a work in progress.  For 28 countries, including the U.S. and most of the Caribbean, the authors want more detail for the next edition.

The Atlas project – no surprise – found that mangrove forests are still being lost three or four times as fast as land-based forests, though the rate of loss has slowed a bit in the five years since the last edition.  There are a few positive developments.  About a quarter of the world’s remaining mangroves are in protected or sustainably managed areas.  Restored mangroves now cover nearly a million acres, mostly in southern Asia, and there are more restoration projects in the works.

The Atlas goes beyond simple geography to explore the relationship between people and mangroves, and how they can – or should – live peaceably together.  Unfortunately the mangroves, especially those near coastal cities, occupy land that can be easily converted to other uses like agriculture, tourism, aquaculture and urban development.  The lure of short-term profit can lead us to forget that in the long run, a live mangrove is worth more than a dead one.  (UNEP studies have found that healthy mangroves produce an economic value between US$1,000 and $3,500 per acre every year, before any contribution from eco-tourism.)

Mangrove systems, including their neighbouring wetlands and sea grass beds, stand between two very powerful forces – water on land, and water in the sea.  When storm water rushes down from the hills, the wetlands and mangroves slow it down, spread it out and trap its burden of soil, rocks and debris.  Without the mangrove system, storm runoff would either flood whatever was built in its place or race into the sea and smother the coral reefs.

When storms and hurricanes bring storm surge and battering waves, coastal mangroves take the first hit.  They break up the waves and trap debris, while their roots and the sea grass hold soil together and keep beach sand from being washed out to sea.

There is also value in the rich biodiversity of mangrove systems.  (Biodiversity measures the number of different plants and creatures that share the same living space.)  Birds, insects, frogs, lizards, crabs, lobsters, oysters, conch and fish spend at least part of their lives in the mangroves, wetlands and sea grass beds.  The sea creatures, including some commercially valuable species, depend on the mangroves as a nursery.

Too many Jamaicans think of mangrove systems as waste ground, full of garbage and mosquitoes.  In some areas that’s true, but the mangroves didn’t produce the garbage.  People did.  And the mangroves didn’t kill off or drive away the birds, bats, dragonflies, lizards, frogs and fish that eat mosquitoes.  People did that too.

So don’t chop the mangroves in your neighbourhood, and don’t let anybody else do it.  Clean them up and let them grow.  Living, healthy mangroves are worth a lot more to you than dead ones.