IN A hut in an Amerindian village, nine hours' drive from Georgetown, Guyana's capital, a young schoolteacher is modelling fish and other animals from ballato, a form of solid rubber gathered from sap.

He sells them in Boa Vista, a nearby town. It supplements the meager income he gets for teaching the village's 54 children. That is one modest way in which a tropical forest yields income.

A few hundred metres down the Essequibo river is another: the Iwokrama field-station, a base for research and for training foresters. It trains some researchers under contract, and it attracts a few eco-tourists.

But neither BALLATO modelling nor the training of researchers generates much revenue.

Back up the dirt road in Georgetown is the one activity that can really pay in this vast expanse of trees: cutting them down for timber.

The world's tropical forests continue to disappear with disheartening speed. Indeed, in spite of much talk and many international efforts, the pace of deforestation appears to have been almost as high in the 1990s as it was in the 1980s, when the world woke up to the issue.

The United Nations' Food and Agriculture Organisation has just published a report on the state of the world's forests which estimates that, between 1990 and 2000, Africa's forest cover declined by 0.8% a year and South America's declined by 0.4%.

Now, international attention and development aid are shifting away from forests.

America's Agency for International Development has put its environment department into a bigger Department of Agriculture, giving forestry a lower profile. Canada's aid agency has got rid of the forestry adviser in its policy branch.

The only senior forestry adviser in the Swiss Development Corporation is retiring, to be replaced by a part-timer. And so on.

Most new World Bank forestry loans in the 1990s went to China and India: China no longer qualifies for cheap loans, and India's are threatened by squabbles between state forestry departments and environmentalists. Other aid donors are put off by the complexity of forest management and the difficulty of spending lots of money quickly.

A World Bank official once famously growled, "Forestry -- 1% of the lending and 90% of the headaches."

THE WOODS AND THE TREES
The search for sustainable tropical forestry has become bogged down in a welter of disagreement about what "sustainability" is meant to achieve and who should foot the bill. Iwokrama illustrates the problem.

In 1992, borne on a wave of environmental enthusiasm, Desmond Hoyte, Guyana's president, offered the world 3,700 square kilometres (1,400 square miles) of pristine rainforest. The United Nations provided $3M to back the project, which aimed to demonstrate the sustainable use of tropical forests.

As the funds have been used up, Iwokrama's donors have come to hope that sustainability might be financial as well as environmental, making money from tourism, training, and timber and other forest products.

In fact, says Iwokrama's retiring director-general, Kathryn Monk, it is difficult -- if not impossible - to combine financial self-sufficiency with environmental sustainability.

In most forests, the obvious source of income is timber. Logging contributes 3-6% of the GDP of tropical countries, and employs 3-8% of the workforce. But it is rarely sustainable financially, let alone environmentally.

Few commercial loggers expect to cut a particular forest more than once. Most of the companies practising good forest management in tropical countries do so not in the wild but in plantations, according to Steve Bass of the International Institute for Environment and Development (IIED), a research group based in London.

"Forestry in natural forests is often run by asset-strippers," as he puts it.

Environmentally sensitive souls in rich countries, buying a new garden bench, may scour the shops for sustainably managed timber. Schemes of forest certification have been expanding rapidly, led by the Forest Stewardship Council.

This body, set up in 1993 and run from Mexico, certifies forests that are managed according to certain environmental and social standards. All told, just over 1m square kilometres had been certified by January 2002, twice as much as a year earlier. But developing countries account for only 8% of the total, and their share is falling.

In temperate forests, most forestry is sustainable, in the sense that repeat rotations of felling and regrowth are possible. But temperate forests contain far fewer species of trees than tropical ones.

A typical hectare of tropical forest will contain around 300 tree species. So the costs of locating and extracting a particularly valuable tree are much lower in temperate than in tropical forests.

Ownership rights, too, tend to be more complex in tropical forests than in temperate ones. Temperate forests are usually treated as assets, and have owners with clear title. Nobody actually lives in them.

That allows them to be managed on a long timescale, which is the essence of sustainability.

Tropical forests, by contrast, are often dwelling places, inhabited by people who rely on them for food but whose claims to ownership are based on tradition, rather than written titles. Such traditions are all too often overridden by governments.

Conversely, in some tropical countries, landless individuals turn up, cut down a piece of forest they do not own, and squat on it. Who owns what is debatable.

That makes conservation hard.

The political instability of many tropical countries also makes management difficult, says David Kaimowitz, director of the Centre for International Forestry Research in Indonesia.

"Well over 50% of the world's tropical forests are in countries that have had violent conflict in the past 15 years," he points out. The world's second-largest tropical forest is in war-ravaged Congo.

"If you can't even manage basic governance, how are you going to keep people out?"

That creates a problem for environmental groups, such as the highly influential Conservation International, which believe that sustainability implies conserving forests in their pristine form, in order to protect the existing mix of biodiversity. The only likely way to achieve that goal is to acquire tracts of forest -- and to protect them successfully from intrusion.

Yet Ruth Nussbaum of Proforest, a company specialising in sustainable approaches to forestry, argues that the toughest question is "not, can we get sustainability, but can we exclude illegals?"

Besides, many foresters argue that the preserved-in-aspic approach is unnecessarily rigorous -- and bound to fail. "We rarely have the option to leave things alone," says John Hudson, senior forestry adviser to Britain's overseas-aid department.

Jeff Sayer of WWF International, a green lobby group, argues that any long-term solution for tropical forests has to involve better livelihoods for those who live around and in them. Big, remote, pristine parks will not survive population and political pressures.

That need not be a disaster for conservation, he says: forests that are well managed for timber also afford good protection to biodiversity. The range of preserved species may be smaller, but "there is very little evidence that, if one species goes, so will lots of others."

It may also be wiser to think in terms of managing a landscape, rather than forests alone.

Some hope that new sources of income will make it possible for tropical forests to combine financial and environmental sustainability. A whole range of markets has recently emerged, in which agencies such as local governments and international donors pay for four kinds of forest environmental services: watershed protection, protecting biodiversity, mopping up carbon and preserving landscape beauty.

But an analysis*[1] of these by the IIED recently drew attention to their many weaknesses.

Markets work well only with clear governance, something that many developing countries lack. Also, they may exclude the poor, or may concentrate on protecting one commodity at the expense of others.

As so often with the environment, doing harm is easy. Knowing how to put things right is hard; and actually doing it harder still. But if donors give up, forests will be left to green extremists and logging companies.

That would be worse.