A VAST, threatening cloud of smoke hovered over good parts of Sumatra, Borneo, Malaysia and Singapore for months.

In parts of Indonesia the sun was invisible and in Singapore people suffered breathing difficulties when the wind blew the wrong way. People in the region complained that they could no longer see a truly clear, blue sky.

Indiscriminate logging on top of a four-month drought had caused blazing infernos reaching an estimated 500 or 600 Celsius in the forests of the Indonesian islands of Sumatra, Sulawesi and Kalimantan ¿ the Indonesian part of Borneo.

Yet not far away, to the accompaniment of a symphony of unfamiliar sounds, I observed a large butterfly of exquisite beauty soar and glide in pure, undefiled rainforest. Riding air currents, only occasionally moving its transparent, black-dotted wings, this elegant, lovely creature as well as its lush surroundings seemed unreal, from another planet.

The setting was the Batu Apoi Forest Reserve in the Temburong District of the Sultanate of Brunei, also on the island of Borneo.

Very few human beings except for Iban hunters and, recently, a few highly respectful scientists, have ever been here. Man has not yet managed to spoil the environment thanks to a deliberate policy of conservation on part of the Brunei government. And thanks to westerly winds, this area has also largely been spared from the suffocating layer of smoke.

It is a remarkable place. "Here," says Dr. David Edwards of Universiti Brunei Darussalam's Biology Department, "in an area 100 metres long by 100 metres wide, there are more than 550 trees with a trunk diameter of ten centimetres (four inches) and over, representing more than 120 different species."

Numbers can be boring, but when Nigel Stork of the Natural History Museum in London discovered 400 beetle species here in just one tree, and when one acre of tropical rainforest is home to some 20,000 different kinds of insects and 100 varieties of plants the mind boggles.

Another marvel is that in the middle of this inaccessible place the Universiti Brunei Darussalam (UBD) and the Royal Geographical Society of the UK established what could be called an Academy of the Rainforest. Its real name is the Kuala Belalong Field Studies Centre, and it operates under patronage of the Prince of Wales.

"We're here to provide a scientific database for UBD to manage the centre as its own preserve," said the Earl of Cranbrook, leader of the project, a biologist, and an expert on the forests of Southeast Asia.

"So we're getting to grips with certain basic elements of biology and the physical geography of the area as well as putting in weather stations, rain gauging ¿ all sorts of things they are likely to need for future research."

The setting for the Field Studies Centre is spectacular. Caught between steep, forest-covered slopes on both sides, strung along the Belalong River are six wooden chalet-type residential houses on stilts, joined by wooden walkways to prevent the ground from being trampled by boots. There is also a large laboratory, a computer room and a dining room where two cheerful Indonesian cooks, Yulis and Martinah, provide a great variety of tasty regional dishes.

Accessible only by longboats expertly operated by Iban tribesmen, the trip through 25 rapids can take anywhere from a dry half an hour to two and a half hours of getting soaked by the river and the drenching downpours as well ¿ all depending on the rapidly varying levels of the river.

Above the riverbanks trees as tall as 200 feet cling to a mere few inches of topsoil on the steep slopes ¿ and this is one of the few chances to actually observe the giant trees from top to bottom since, once in the rainforest, you can rarely see the sky, much less treetops.

The boat trip also offers a rare opportunity to feel the warmth of the sun on your skin. Most of the scientists and students become fit as Ghurkas but paler than mid-winter English.

Here, struggling in the wet one could easily lose track of the ultimate aim of this effort: To educate the world to the value of the tropical rainforest, and to preserve it.

Prince Charles, patron of the project, sent the following message at the time of the inauguration: ". . . the world's tropical rainforests represent one of the most fragile, most diverse, and least understood of all natural ecosystems. They are also currently perhaps the most threatened."

British politician Chris Patten, in a speech, offered some good reasons why such biological diversity should be conserved: ". . . species of plants and animals are disappearing fast, some of them before we have even registered their existence.

". . . as natural products have been a major source of medicines and pharmaceuticals, we should be investigating the other shelves in the larder rather than sweeping things off them."

The rain forest is an important, underexploited source of foods as well.

The ground of the Batu Apoi Forest Reserve is crawling with leeches, millipedes, centipedes, scorpions, giant and small ants, yellow-throated King Cobras, pit vipers, plus the wet PhD students and full-fledged scientists who bravely attempt to conserve them.

Leeches, the wet, and the steepness of the terrain are their biggest problems. Snakes, though very abundant and an indication of virgin forest, mostly stay out of sight.

Simple walking is impossible as there is hardly a straight stretch anywhere within the 50 square kilometres of the reserve. You climb, slip and skid along the forest slopes in a strange twilight which is only broken by the pitch darkness of night, or an opening where a giant tree has crashed down, admitting a shaft of light from above.

There is no intense heat. Temperatures hover around the 80s, but there is 100 per cent humidity and any physical effort is enough to make sweat glands pump furiously. Even without rain one is constantly dripping wet ¿ hair, glasses, instruments, cameras ¿ all wet. Clothes never seem to dry out.

The wettest of all the scientists was Alan Dykes, a tall, lanky PhD candidate and physical geographer from the University of Bristol. On the go day and night, Alan's task was nothing less than finding out what rain does to the rainforest, what it does to the topography and drainage patterns of the area.

One of his studies is a perfect hands-on lesson in what happens to rainforest soil when it is disturbed. On a slope Alan fenced in with solid timber three plots of jungle, each five metres by 2½ metres, in order to create a controlled area.

In the first he cleared out all the leaves, all the roots and branches, leaving just bare soil. The second had all the loose leaves and branches taken out, leaving in just the roots and the topsoil. In the third he left the ordinary forest floor ¿ rotting leaves, roots, everything.

After a heavy rain we went to observe the results. From the first cleared plot a large bag of sediment was washed out into a measuring device. It was so heavy we could hardly lift it. From the second area not nearly as much topsoil had been lost. Amazingly, from the third one only about a large fistful had been washed off, proving that the leaves and the roots are a perfect protection for the scarce few centimetres of essential topsoil.

This brought home what one has read and heard about but too often ignored: After the scarce two or three inches of top soil are gone, absolutely nothing grows in the clay or on the rocks below. It also becomes more than obvious that insensitive, indiscriminate logging will eventually create a desert out of such an area.

Something like a billion people in the Third World are now suffering the effects of this kind of exploitation in terms of loss of water resources, homes, food, fuel and other raw materials.

Dr. Joe Charles, of the Department of Biology of UBD, assisted by the Warden of the Field Studies Centre and expert woodsman Samhan bin Nyawa, studied the distribution and abundance of mammals and birds in the forests at Belalong.

"We cover the whole range of primates," said Joe. "Mouse deer, Bornean gibbons, langurs, civets, sun bears, barking deer, hornbills, giant squirrels, pheasants, pig-tail macaque ¿ whatever large animal comes our way. We do this survey ten times per transect, each being two kilometres."

I said that I didn't see any animals in the forest ¿ I just heard things.

"You have to be there at first light," says Joe. "Sometimes you just want to sit still at a vantage point. Yesterday I saw a barking deer just ten metres away from me. It came right up, not knowing I was there. It was a beautiful male, lovely horns. Suddenly it stopped in its tracks. It began to knock its teeth ¿ an alarm call. Abruptly, it bounded away, barking. Then it stopped and roared before it shot off."

Another striking animal they see is the giant squirrel, about one metre long, from nose to tip of the tail. Flying lizards are also common here.

Said Joe: "The lizards are very cryptic ¿ the same colour as the bark of a tree. You'll never see it unless it moves. It has two sheets of skin between the forelegs and hind legs which it uses to manoeuvre in the air when it launches from a high place to lower ground."

Of the cat family, there is the marten, the Malay weasel, and the clouded leopard which is on the endangered species list. Somewhat less glamorous is the bearded pig: "They're enormous. I saw one of them standing on its rear legs pulling down a rattan plant ¿ a fantastic sight. One chased me the other day ¿ it followed me for quite a while. I panicked, ran, and fell in the bushes. He gave up after a while . . ."

The closest thing to a monkey I saw ¿ the real ones were audible but invisible to me ¿ was Carlo Hansen, intrepid curator and researcher from the Botanical Museum of the University of Copenhagen who studied the taxonomy of Melastomataceae, better known as Singapore rhododendron.

Wearing a beat-up old pair of sneakers without socks and a pair of shorts, clinging to roots, trees and lianas, Carlo climbed straight up and down the slipperiest and slimiest of slopes searching for plants. While his colleagues wore boots and long trousers tucked into socks for protection against leeches, Carlo preferred to just pull the leeches off.

"There are," said Carlo, "perhaps 50 species of Singapore rhododendron in the area.

"It never ceases to amaze me when I come back to the jungle how few flowers one actually sees. You know the place is teeming with life but 99 per cent you cannot see. Most of it, of course, happens up in the canopy. That's another world."

Probably in the nick of time, Dr. Kamariah abu Salim of UBD is working with tribal medicine men to extract some of their wisdom before it is irretrievably lost.

"The Malay people still use traditional medicine," she says, "but the Iban, the people of the rain forest, now just go to the hospital since it is free. One has to be very careful or things get lost."

So far they have identified 162 plants with nutritional or medicinal use.

"I've brought with me medicine men from three different tribes," Dr. Kamariah says. "They just walk through the forest and say: 'Oh, this is the plant we use for so-and-so'. And we collect. Then he gives me the local name. So far I've collected more than 100 species of plants that haven't yet been identified on a species level, only on an indigenous level.

Dr. David Edwards is doing a survey of ferns in the Belalong area: "We have something like 400 different ferns in Brunei and about 250 in Belalong. So far there are about four species I cannot identify so there's a good chance those are new."

Edward's fascination with ferns is easy to understand: "They're an ancient group. About 350 million years old. They've outlasted just about everything. Ferns were there before the great cycad forests of the dinosaur era which gave way to the flowering plant forests we have in the tropics now. The ferns developed some kind of antidotes and successfully lingered on in dark and damp areas. They're restricted to damp areas because ferns need free water for their sperm to swim through."

In addition to the scientists, two artists were recording remarkably life-like images of the rain forest. But the one thing their paintings could not capture was the amazing sounds of the forest.

At dawn every morning amid myriad other sounds from near and far, one lonely bird was especially noticeable as it seemed to attempt a simple melody that it never completed. Trumpet-like blasts from a type of cicada started a little later whilst others whined like high-speed chain saws. Other insects just whirred on anonymously. During the morning unseen gibbons whooped and screeched from the treetops whilst punctually every evening 'The Six O'Clock Cicada' let its presence be known ¿ just before six.

A highly sophisticated new tool will ease the task of visiting scientists in the future. John Wills and Kam Tin Seong have set up a computer-based Geographical Information System ¿ which is a way of putting all the accumulated information on to one map.

"First we enter all the topographical data," Wills says. "Then, overlaid, come all the other facts from the scientists about soil, vegetation, climate, animal life and so on. This means that the next line of scientists will have all the groundwork ¿ and their own work will be added in turn."

The base having been prepared by the Royal Geographical Society and the Universiti Brunei Darussalam, the university is now developing its own research plan for the next ten years, involving scholars from all over the world.

"What we are doing is to create a major international centre of excellence for rainforest research and education," Professor Sharom Ahmat of UBD said. "The Sultanate of Brunei will ensure that there is no human encroachment in the area and it is going to be adjacent to the national park that will now be created here."

Another task is to attract the attention of Bruneians themselves who generally have little interest in their forest. Already, groups of about 14 Bruneian children at the time go up to the center for four-day courses every Thursday to Sunday, accompanied by some of their teachers. They are taken on trails through the forest where things are pointed out for them. At stops along the way they do little projects like drawing. The children seem to be thoroughly enjoying themselves.

On the wall of David Edwards' office at UBD hangs a frightening satellite photo. It shows Brunei surrounded by the neighbouring Malaysian state of Sarawak. Total greed having ravaged Sarawak's forests, the map is literally much greener on the Bruneian side. On the photo Sarawak is clearly seen turning yellow ¿ and logging roads can be spotted right up to Brunei's borders.

Rather than profiting from sustainable, restrained logging which environmentalists like Lord Cranbrook support, at the current rate of extraction all the best, tallest and most valuable trees in Sarawak outside national parks will have been obliterated along with most life in them within a few years. And local forestry people admit that if this continues, before long Malaysia will have to import timber.

Oil-rich Brunei is far better off economically than Sarawak, but seeing this disturbing development so nearby and being aware of the raging forest fires on the very same island, I asked Lord Cranbrook whether he saw any threat to this particular region.

Said he: "Quite the reverse. Since we've been here the Sultan's government has declared its firm intention to dedicate the whole of this Upper Timburong Valley including the Belalong Valley as a national park ¿ this means an area of over 50,000 hectares."

But no ruler lasts forever. It is to be hoped that the children who now are given the chance to visit this 'Academy of the Rainforest', some of the future leaders will acquire the wisdom to carry on in the same vein, to see that the more we discover now about the importance of forests, nature's own warehouse, the more we can expect ours and future generations to care for their survival.

PS: Very sadly, veteran researcher Carlo Hansen died of fever contracted in the rainforest.