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VOL. 7.7

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Stars In Their Own Right

By Ken Scott

It’s an eerie world, strung between land and sea. It’s also a marine nursery, a haven for wildlife, and a biologist’s dream. Pushed out of the media limelight by more exotic-looking rain forest and coral reefs – Thailand’s mangrove swamps are nonetheless stars in their own right. Their importance is becoming painfully clear as they and others like them in Southeast Asia are coming under increasing threat.

Mangrove swamps are found in salty, brackish water in tropical regions. While the mangrove forest of the Phuket regions aren’t as extensive as Florida’s famous Everglades, they do display a biodiversity which intrigues a new generation of scientist – researchers whose predecessors dismissed these forests as virtual mono-cultures compared to the more exotic rain forest and coral reefs.

Dave Williams, director of Sea Canoe Thailand in Krabi, laughs at people who say that the mangroves forests are fascinating ecosystems, crucial to people living on tropical coasts. The Bangladeshis, for example, have learned the hard way – degradation of mangrove forests causes serious coastal flooding and many deaths every year in that country.

Mature mangroves grow to over 25 metres. There are still some pockets of tall mangroves in Ranong, in Thailand. Due to repeated cutting for charcoal, however, most mangroves in the inner Andaman grow no higher than 5-10 metres.

Worldwide, mangroves are being recognized as spawning, nursing, feeding and sheltering grounds for a variety of species of great ecological importance and commercial value. In the Phuket area alone, mangroves are a haven for small-clawed and hairy-nosed otters, monkeys, monitor lizards, spectacled and dusky langurs, crab-eating macaques and many kind of snakes. There are still isolated reports of crocodile sightings. Bird watchers from around the world come to marvel at migrating sandpipers form Russia, Spiralling Brahminy kites, and two species unique to Andaman mangroves: the brown-winged kingfisher and the mangrove pitta.

Mangroves also have medicinal value. On some inner Andaman coasts, the locals still use namnong, a gray-leafed shrub from the mangrove forest, to cure lumbago and thrush. One holly species is used locally to cure impotency and VD. Sap from another kind of mangrove will blind you if it touches your eye; taken internally in mild doses, however, it is a cure for stomach upsets. Other mangroves are used to prepare medicines to ease the pain of kidney stones and menstruation. Universities worldwide are now evaluating further potential uses for mangrove leaves, bark, fruit and mosses.

Some mangrove villagers know how to make a weak wine with the fruits of the taboen tree. They use the nipa palm (jak) for roof thatching and to make cigarette wrappers. The roots of on guy thale are used as a poison.

Specialists in mangrove studies now appreciate the ingenious evolution of these trees. In an effort to cope with water logging and salinity, some mangroves have developed by flaky bark, an adaptation which helps slough off excess salt. The finger-like shoots sticking out of the ground excrete excess and allow oxygen to enter the root system.

The majestic claw-like stems around the base of swamp trees prevent them from falling over on the shifting silt that is pushed to and fro on the tide. The same roots also form a protective cage to reduce competition from other seedlings.

For all their clever adaptations, mangroves still have their troubles. In particular, one primate is a major problem – the human being. Coastal ecologists point to survey evidence indicating there were 800,000 acres of mangrove in Thailand in 1961. By 1989, people had removed 50 percent of this.

A swing away from traditional activities is at the root of the problem.
The small-scale fish farming found along the Andaman coast is quite sustainable. The real problems in Thailand are charcoal production, land reclamation, and, more recently, get-rich-quick prawn farming.

The first of these, charcoal production, does not have to be a threat. If well managed, it can be sustainable. In Malaysia there are mangrove forests which have been exploited for charcoal production for more than 100 years. In Thailand, mismanagement prevails, despite mangrove management plans which date back to 1946.

To their credit, charcoal producers rarely clear-cut a whole area. They usually enter the mangrove to select individual trees – often the larger, mature ones. The brick kilns, much in evidence in mangrove forests in Phang Nga and Krabi, generally run on a 27-day cycle. Mangrove trees are cut into polewood and stacked in the ovens. The wood is set on to smoulder, with only limited oxygen allowed in through the grates. Then the grates are sealed, maintaining a high caloerific value in the end product.

Each kiln contains around 500 kilos of charcoal, which sells at around 3 to 5 baht a kilo. More people switching to gas and oil cooking means demand and prices have dwindled.

“Many companies don’t respect the law,” says Sombat Poovachiranon, a marine biologist in the coastal ecology department at the Phuket Marine Biological Center. “ They just cut and don’t replant. The area degrades and is turned to prawn farming.”

That’s when problems start. The Fisheries Department encourages coastal dwellers to farm black tiger prawns, which are in increasing demand world-wide. Some villagers used to say that trading in heroin was the only way to get rich quick. Now they say trading in tiger prawn will do the trick instead. It is illegal to start a prawn farm in a mangrove area; but a lot of mangrove is chopped down by prawn farmers as government officers turn a blind eye.

Areas along the shores of the Andaman are suitable for prawn farms because the waterways act as a convenient outlet for organically rich wastewater. The nutrient-rich waste, however, consumes oxygen in the water, sterilizing the natural breeding grounds of fish, crabs and prawns. Mangrove roots suffer from a lack of oxygen. In turn, prawn farms often suck in their own polluted water from dying mangrove areas – which kills the prawns and destroys the mangrove ecosystem. By law, farmers should maintain at least one pool to allow sedimentation of wastewater before disposal. They often use this for prawn production instead, and all for nothing but short-term gain. The destruction that results is all the sadder because it is preventable - as with charcoal production, properly managed prawn farms are not a threat to mangroves.

On the conservation front, scientists say woefully little mangrove remains in Thailand’s national park areas. The government has formally designated about 10 percent of mangrove for conservation.

For the remaining trees, there is one major hope. The mangrove ecosystem is a relatively sturdy one, and it can regenerate, reaching relative maturity in 15 years.

Tourists can now explore the mangroves of Krabi and Phang Nga on nature–sensitive sea canoe expeditions, which don’t use noisy and dirty longtail boats. “The only way to go through mangrove and see wildlife is to paddle,” says Dave Williams, who worries about abuse of mangrove. “I’d like Thai people to come on my trips to see what they have and what they’ll lose if they’re not careful.”

Contact either Sea Canoe Thailand in Phuket on (076) 212 172, or Krabi Canoe Tour on (01) 723 1128. The Sirinat National Park on Phuket is also worth visiting, as authorities are building a visitor center and walkways through the mangrove bush.