Battling the weather with branches and roots | Environment| All topics from climate change to conservation | DW | 20.07.2010
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Battling the weather with branches and roots

A new book about the state of the world's mangroves urges governments to protect their saline trees and shrubs or live to regret it.

An aerial shot of a mangrove

Mangroves can provide humans with invaluable services

It wasn't all bad news, but it was bad enough.

In the first global assessment of the situation for more than ten years, the "World Mangrove Atlas" paints an honest picture of the depletion of tree and shrub life along tropical and sub-tropical coastlines.

One fifth of all mangroves are thought to have been lost since 1980, most frequently to shrimp farming, agriculture and coastal development.

It is estimated that the world once boasted some 200,000 square kilometers of the complex shoreline eco-system, but that a quarter of that has been felled in the interests of commercial progress. Uprooted and discarded three or four times more quickly than non-coastal woodland, mangroves have become victims of location.

And in an effort to halt their destruction, scientists have warned of the economic and ecological consequences of negligent behavior.

Mark Spalding, senior marine scientist at the University of Cambridge and lead author of the new Atlas, told Deutsche Welle that in losing their coastal plant life, local communities are invariably the first to suffer.

A large pond with some bouys and people in it

Aquaculture, like shrimp farming, can render mangrove regions barren

"Many of the world's poorest people live adjacent to mangroves in the tropics," he said, adding that they don't stand a chance when wealthy buyers come in and flatten the trees and shrubs to convert the land to shrimp aquaculture.

Diggers are brought in to create inter-tidal ponds which are flushed with tidal waters and then filled with shrimp and chemicals to ward off illness.

"But eventually the stock picks up a disease, the remnants of which sit in the sediment while the owners move on leaving barren useless land where there used to be mangroves," Spalding said.

Good for a few, bad for the rest

Few locals are invited to work on the farms and with poor fishing yields, as a result of the decimation of their natural habitats, whole communities are suddenly unable to sustain themselves.

Jim Enright of the Asia branch of Mangrove Action Plan (MAP) underscored the depth of the problem for local people generally used to getting everything they need from the saline shrubs and trees that grow in their midst.

Tree against an orange background

A red mangrove in Florida

"We often refer to the mangroves as supermarkets for locals," Enright told Deutsche Welle. "People collect snails, crab and fish, building supplies for making fish traps and shelter, and they use plants for traditional medicines and natural dyes."

It is a lot to have to forego so that a handful of individuals can make a sack of cash, and it's not even the whole picture.

Weathering the storm

As well as providing people in Africa, South-East Asia and Latin America with a means of day-to-day survival, mangroves also protect them from the elements.

And in an age where weather disasters are very much in the public consciousness, the critical role of saline forestry in coastal defense cannot be overstated.

"We know they are very effective in stopping winds and waves, and to a lesser extent, tsunamis," Enright said, adding that they also "protect property and lives" during the strong winds of the monsoon season and the cyclones that batter South-East Asia annually.

Thick mangrove forest with lots of roots and greenery

Dense foliage helps break the wind and water fall

Their tangled mass of roots, shoots and branches act as a buffer for fierce storms rolling in from the sea, and Spalding even goes so far as to say that mangroves have what it takes to slow down the frightening process of rising sea levels.

"They allow sediment to settle on the ground so it can build upwards," he said, adding that there are some deltas where the ground is growing so fast that it will outbid sea level rise.

Undoing the damage

The hope is that the Atlas will help raise awareness of the benefits of these salt-water groves and spur governments and local groups into action to fight against any further destruction while simultaneously working to restore former mangroves to their natural glory.

And there is already significant evidence of a willingness to undo some of the damage done.

Tanzania has put all its mangroves under protection, and new trees and shrubs have been planted or encouraged to grow through measures such as waste removal in a range of other countries including Australia, Brazil, Cuba, Indonesia, Philippines and Thailand.

An aerial view of a small island surrounded by its disintegrated beaches

Beaches of an uninhabited island washed away in the 2004 tsunami

MAP works with local people in Thailand on what it calls ecological mangrove restoration, a strategy which entails a detailed historical analysis of the soil and hydrological requirements before planting. Enright says this enhances the chances of successful growth of seeds swept in on the tides, thereby recreating the same richly biodiverse eco-systems of old.

However, getting to the coastal regions in need of gentle cultivation is easier said than done. Talking of the difficulties in gaining access to land abandoned by shrimp farmers, Enright said there are a lot of ownership hurdles to be cleared before restoration can begin. But he and others like him are dedicated to the task in hand.

"On the whole people are doing the right thing," Spalding said. "But mangroves are still declining too fast and we would be doing the world and ourselves a favor if we would just stop chopping down mangroves altogether."

Reporter: Tamsin Walker
Editor: Nathan Witkop

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