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Natural dams

February 18, 2010

Mangroves are one of the most important and most endangered ecosystems. They've disappeared rapidly in the last decades. But now reforestation is under way in the Philippines to protect coasts and bring back fish.

Mangrove trees
Mangroves serve as natural dams against rising sea levelsImage: WWF / Jürgen Freund

Coastal regions are considered one of the richest biospheres in the world. They're also one of the most vulnerable, as the massive Asian tsunami of 2004 clearly demonstrated.

Climate change has led to rising sea levels and extreme weather conditions such as typhoons are expected to occur more frequently. Coastal areas and their inhabitants are in danger of becoming the big losers of climate change.

Particularly vulnerable are places where coastal forest cover has been cleared away, since these forests once served as natural dams against the sea.

Problems in the Philippines

The Philippines consists of 7,107 islands with a 36,287-kilometer-long (22,548 mile) coastline. It's hardly surprising then that there are acute concerns there about coastal deforestation. On Negros, the country's fourth-largest island, some 70 percent of mangrove forests have been cleared away in the last decade.

Now, a rethinking has set in after record floods in February last year combined with steadily rising temperatures and sea levels.

People living along coasts have suffered heavily as a result of climate changeImage: Robert Donauer

"These are clear signs that we now must deal with environment protection," Governor Emilio Macias said at an environmental conference last year which drew fishermen, farmers, green groups and aid workers. "Not for us, but for our children, our grandchildren and all further generations."

Negros now has plans for reforestation.

Mangroves are a group of trees and shrubs that grow in saline coastal habitats. They include 20 different tree species that have adapted to the extreme living conditions on saline coasts and brackish estuaries.

They grow between the 30th latitudes north and south of the equator, but also in pockets in Japan, the Bermudas, in Australia and New Zealand. Their thick mass of roots build a natural defense against storms, high waves, floods and erosion. Regions with intact mangroves suffered far less damage during the tsunami of 2004.

Large carbon storehouses

Mangroves also play a large role in lowering greenhouse gases. A hectare of the trees can absorb one and a half tons of carbon dioxide from the atmosphere. The trees store an additional 700 tons of carbon in their massive roots each year. Mangrove forests also provide a safe habitat for fish, mollusks, crabs and several other species.

The thick roots of mangrove trees build a natural defense against floods and erosionImage: Robert Donauer

Much like coral reefs and rainforests, mangroves are considered one of the most productive ecosystems on the planet. They're also one of the most endangered habitats. Around the world, they're disappearing twice as fast as rainforests -- largely because of booming shrimp farms which are edging out mangroves. The draining of forests to convert them into plantations and agricultural land has dramatically worsened the situation.

"The decline is really rapid," marine biologist Onno Gross said. The Hamburg-based scientist runs a project called "Mangreen" which helps to promote reforestation in southern India.

"Half of the mangrove stocks there were destroyed in the last decades," he added.

That's had disastrous consequences, and not just for the protection of the coasts. A large number of economically important fish species reproduce in mangrove areas. Coastal fishing suffered a drastic yield decline in regions where large areas of mangrove forests were hacked away.

A rethink needed

Given the huge economic and ecological importance of mangrove forests, a number of regions in countries such as Indonesia, Thailand, India, Vietnam, Brazil, Barbados and the Philippines have begun reforestation.

The European Union and the United Nations are supporting reforestation projects with millions of Euros in funds.

The GTZ, a German state-funded international organization for sustainable development, is working on a project in the Philippines to educate people about the benefits of reforestation.

Biologist Gross said it's a good beginning but what's needed is a rethink. "Let's not fool ourselves. It's not about just planting a few trees. In many places, you need to build a functioning civil society to protect the environment."

Till that happens, experts suggest cutting down on shrimp consumption to save mangroves. Environment group, The Mangrove Action Project, has launched a campaign titled, "Shrimp Less, Think More" to save mangrove forests on the Negros islands in the Philippines.

Author: Oliver Samson (sp)
Editor: Mark Mattox

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