Monday, February 07, 2005

why save the forests?

fear of big waves is no reason to plant mangroves

By Jason Overdorf and Eric Unmacht
(This article appeared in Newsweek International in February 2005).

Feb. 14 issue - In the aftermath of a natural disaster like December's tsunami, some stories have happy endings. V. Selvam's began when the giant waves came crashing into the mangrove forest of Pichavaram on India's Tamil Nadu coast. Selvam, a biologist who had been working to restore the forests, made his way to a nearby village as fast as he could, expecting the worst. Instead, he found relieved villagers regaling him with anecdotes. Eyewitnesses told Selvam that the mangroves had channeled water into lagoons and through canals, sparing the settlements meters from the shore. "I couldn't believe it," he says.

Similar anecdotes from all over the tsunami-affected region have had a special appeal to environmentalists and conservationists, who argue that if it weren't for the destruction of mangroves and coral reefs, which form natural barriers to waves, the death toll might have been far lower. Some of the hardest-hit countries have taken this admonition to heart and made mangrove restoration a pillar of their restoration efforts. Indonesia has promised to spend $22 million to replant 600,000 hectares of mangroves along its damaged coastline. The state of Kerala in southern India announced a plan to spend $8 million to create a protective barrier of mangrove plants. And forest officials in Thailand, Malaysia and Sri Lanka are evaluating similar schemes. The problem is that the idea of developing physical barriers, natural or otherwise, to protect against future tsunamis is "pie in the sky," says Doug Masson, an oceanographer at Southampton University in England.

There's no denying that mangroves did save some villages, like those on the Indonesian islands of Sabang, Nias and Simeulue, which were spared the worst damage even though they were close to the earthquake's epicenter. The faulty logic comes in generalizing these experiences to the entire region. For one thing, mangroves don't grow everywhere—only 10 to 12 percent of India's coastline and 25 percent of Indonesia's, for instance, naturally support mangroves. If 20 percent of these forests had been lost to development between 1980 and 2000, as the United Nations' Food and Agriculture Organization says, or even 50 percent, as some conservation groups insist, that would have left only a small fraction of coastlines vulnerable.

The forests, too, cannot be planted just anywhere. The Indonesian government is considering laying a belt of the trees around the entire province of Aceh, which was devastated by the tsunami. But mangroves flourish only in high-salinity soils common to areas that combine an inflow of tidal water and an outflow of fresh river water; they die in sandy soils, which make up the lion's share of beaches. Several efforts by NGOs to plant mangroves in Indonesia have failed. "These are very well-meaning projects, but people [tend to] throw one species in the mud, and basically, after two or three weeks, they're dead," says Jan Steffen, a UNESCO expert in coastal development. Says the FAO: "Planting of mangroves where they did not previously exist is rarely going to work. There is a reason why they were not there in the first place."

Even if it were possible to ring the entire Indian Subcontinent with mangroves, the strategy still wouldn't work in all cases. Because the size of a wave hitting the shoreline depends to a great extent on coastal geology, the tsunami took on different shapes in different places. Locals in Indonesia reported seeing rolling, riverlike waters flooding some areas and 30-meter-high, bulldozer-like walls of sea flattening others. A 50- to 100-meter band of mangroves might have made a difference where the ocean floor slopes gradually to the shoreline and the wave traveled only a few meters inland. But in places like Lhok Nga in Aceh, where valley walls funneled the waters up to 35 meters high and the tops of palm trees were snapped off "like matchsticks," says Steffen, a few mangroves wouldn't have helped.

In the absence of any definitive studies on the effect of mangroves on waves, it would be wiser, says Southampton's Masson, for Indian Ocean nations to invest instead in civil-defense plans that include educating the public about what to do if such a disaster recurs, and a regionwide early-warning system like the one that exists in the Pacific. Still, protecting and restoring mangrove forests would provide habitats for juvenile fish, crabs, shrimps and mollusks; nesting sites for hundreds of bird species, and shelter for the Royal Bengal tigers of India and Bangladesh, among other endangered animals. Those are worthy enough reasons for planting trees.

© 2005 Newsweek, Inc.