Drinking rainwater from banana leaf, Nigeria. (c) I. Uwanaka/UNEP peopleandplanet.net
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Drinking rainwater from banana leaf, Nigeria. (c) I. Uwanaka/UNEP
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forests > factfile > treasures of the forest

Treasures of the forest

Posted: 20 Oct 2003

The world's forests provide the world with an abundance of invaluable goods and services. Forests absorb carbon dioxide, the main climate-changing gas and produce oxygen. They anchor soils, regulate the water cycle, protect against erosion and provide habitat for millions of species of plants and animals. Take away the trees and intricately linked ecosystems unravel into dust.

Quick guide to this section:

Wooden world (top)

Wood and its products rank third in value among the world's commodities trailing only oil and natural gas. Wood-based products such as timber, fuelwood, and pulp for paper and packaging contributed over $400 billion to the global economy in 1990 - an amount greater than the gross national product of Saudi Arabia and Switzerland combined.

The demand for these wood products is expected to increase by half by 2010. Unfortunately, due to over-harvesting of tropical hardwoods, there are signs of a timber famine ahead.

Nearly 3 billion people in developing countries rely on wood for household heating and cooking. Fourth-fifths of wood harvested in developing countries is consumed as fuel.

Such is the pressure on fuelwood that many families now spend between 1.5 and 5 houses each day collecting it. Often girls must sacrifice their schooling to help their mothers in the search for fuelwood.

There has been much debate about the true scale of the 'fuelwood crisis' but according to one estimate half of those using fuelwood cannot do so without overcutting tree stocks.

More than wood

The value of forests lies in much more than the wood supplies they contain. Referred to collectively as non-wood forests products (NWFPs), these include medicines derived from forest plants and animals, industrial crops such as oil palm and rubber, nuts, fruits, beverages and other foods, as well as food flavourings and additives such as herbs, spices, and gums.

Spices of the forest::� Sophie Boussahba / Still Pictures
Spices of the forest
� Sophie Boussahba / Still Pictures

With an estimated value between $1billion and $10 billion, the current trade in NWFPs is minor compare to timber but its potential value, especially in connection with the production of so-called miracle drugs is immense. Already pharmaceuticals such as antibiotics, antivirals, analgesics, tranquillisers, diuretics and laxatives contain substances derived from tropical forests plants.

A study by the US National Institute of Health found that nine of the ten most-prescribed pharmaceuticals in the United States were derived from compounds produced by plants and animals found in forests. They include drugs that combat heart disease, leukaemia, cancer and HIV/AIDS.

Forests provide a source income for some 200 to 300 million people who earn much of their subsistence income through non industrial forest products. These include simple handicrafts, furniture and foods. Forests are home to some 150 million indigenous peoples who depend on forests and forest resources to sustain their way of life and cultural identity.

Diversity of life (top)
Natural forests are the single most important repository of terrestrial biological diversity. The term biological diversity or biodiversity, refers collectively to the full range of species, genes and ecosystems in a given place. The life-sustaining services and commodity-producing functions of forests depend on this biodiversity.

 The rosy periwinkle contains cancer curing properties::� Kevin Schafer / Still Pictures
The rosy periwinkle contains cancer curing properties
� Kevin Schafer / Still Pictures

Tropical forests, while covering 6 per cent of the planet's surface, are home to at least half the world's known animal and plant species, and offer an unknown genetic library that could spur advances in medicine, food production and materials development for enerations to come.

According to WWF, tropical forests alone are thought to house between 10 to 60 million species. A single hectare of Peruvian rainforest contains nearly 300 species of trees, compared to just 50 indigenous tree species in Europe.

In addition to 2,650 species of trees, the ancient tropical forests of Malaysia are home to 300 species of mammals, 700 species of birds, 350 species of reptiles, 165 species of amphibians, 300 species of freshwater fish and uncounted millions of invertebrate species. Many of these species are endemic to tropical forests, meaning that they are highly adapted to local conditions and are not found outside the immediate area where they evolved

Pollination and pest control (top)
The influence of forests extends far beyond their boundaries. For instance, birds, bats and insects that winter in the forests of Central America distribute seeds, control pests and pollinate flowering plants in the United States and Canada. Many of these species therefore reduce our dependence on pesticides. Some examples are given below:

The Mexican brown bats gorge on insects that plague corn, cotton and potato crops in the US, saving American farmers millions of dollars while slowing the build-up of persistent organic pollutants in groundwater supplies and the food chain.

Painted weevil::� WWF / Ron Pertocz
Painted weevil
� WWF / Ron Pertocz

Until 1980 the pollination of palm trees in Malaysia was undertaken by human hand, an inefficient and expensive process.The import of stocks of weevils from Cameroon's forests to Malaysia for the pollination of its palm trees saved Malaysian plantation owners some $120 million in 1981.

Asia's rice crop was hit in the early 1970s by a 'grassy stunt' virus that threatened to devastate 300,000 square kilometres of rice fields. Fortunately, a single gene from a wild rice in an Indian forest offered resistance against the virus. In 1976 there emerged another virus, known as 'ragged stunt' disease, and again the most potent source of resistance proved to be a wild forest rice. In India alone, the introduction of wild rice strains (plus primitive cultivars) has increased yields by $75 million a year.

Environmental services (top)
Forests perform a range of environmental services even more bountiful and valuable than material products they provide. These environmental functions protect and maintain ecosystems at local, regional and even global levels.

water cycle regulation: Forests play a significant role in evapotranspiration, a word that embraces the exchange of water between trees, soil and the atmosphere.

The Amazon River basin derives half its rainfall from local evapotranspiration.

Between 75 and 95 per cent of rainfall in the Congo River basin similarly is cycled from the forest itself. When the trees disappear, so does much of this rainfall, putting at high risk plant and animal species that evolved in a rainforest climate.

soil conservation: Forest cover protects the underlying soils from eroding. Leaves break the fall of pelting raindrops, branches break the force of wind and a network of roots hold soils in a vice-like grip. The steady accumulation of plant and animal litter decays into soft flexible humus that nourishes more plants, binds soil particles, acts as a sponge to store water and supports a web of subsoil life. In steeply sloping watershed areas, trees reduce the risk of landslides. Clearing away trees undoes every on of these benefits. Without protection from the elements or a source of humus, soils compact (harden) and grow crumbly that the least flow of water carries the soil away in fine grains or large clumps.

A World Bank review of 80 studies found that the rate of soil erosion is 10 times higher on lands where slash and burn farming is practised than in natural forests undisturbed by human activity. One reason that agricultural yields have fallen in sub-Saharan Africa is that vast amounts of forest cover have been decimated, hastening soil erosion and loss of nutrients.

Watershed management: A watershed is an area of land drained by a river system and its tributaries. Watersheds can be visualised as physical basins, the "rims" of which are ridges of high land that separate adjacent watersheds. The geography of watershed areas intimately links the health of upstream and upland forests with the productivity of downstream regions.
With the expansion of population, people and human activities have migrated upstream and up the sloping banks of the rivers, putting increasing pressure on mountain forest areas. The increasing loss of forest cover in these areas begins a vicious cycle of degradation throughout the entire watershed.

A report by the World Resources Institute (WRI) concluded that 42 per cent of the world's primary watersheds have lost more than 75 per cent of their original forest cover - that is, forest cover believed to have existed prior to human influence some 8,000 years ago.

Over 75 per cent of land in the Ganges watershed has been cleared for farming while only 4 per cent remains forested WRI reports. The annual cost of watershed deforestation in India alone was estimated as far back as the early 1980s at more than $1 billion.

The Yangtze watershed in China, home to nearly 400 million people, has lost 85 per cent of its original forest cover which once absorbed and held huge quantities of monsoon rainfall. The Chinese government acknowledged that extensive logging was to blame for the floods in 1998 that killed more than 3,000 people and caused over $20 billion in damage in 1998. It has now banned the cutting of old-growth forests in a desperate attempt to halt further damage in the Yangtze watershed.

Other watershed areas under pressure include the valleylands of the Irrawaddy, Salween, Chao, Phraya and Mekong Rivers in Southeast Asia. The continued degradation of watersheds due to agricultural extension and deforestation will become even more pertinent as the world population continues to grow and the pressure for freshwater mounts, heightening the potential for conflict in these regions.

Climate control (top)
Most important at a global level is the role forests play in regulating the earth's climate. Forests are natural carbon sinks, or storage reservoirs for carbon. But when this is bulldozed or burnt, forest can become a net source of carbon in the atmosphere.

The world's forests currently store some 830 billion metric tons of carbon - about the same amount of carbon as the atmosphere holds in the form of carbon dioxide. Roughly 40 per cent of this carbon - 330 billion tons - is contained in forest vegetation, with the remainder contained in forest soils and roots.

Tropical deforestation and forest degradation account for roughly one quarter of all the CO2 emissions that result from human activity. Forest fires, both natural and man-made, are a major source of atmospheric carbon. Of the roughly 7.6 gigatonnes of carbon dioxide emitted into the atmosphere and contributing almost half of greenhouse-effect processes, 1.6 gigatonnes (plus or minus 0.4 of a gigatonne) come from forest burning in the tropics, almost all the rest stemming from combustion of fossil fuels.

Future acceleration in the loss of tropical forests or of Siberia's huge boreal forests could lead to significant additional emissions of CO2, further hampering international efforts to combat global warming.

Programmes that reverse the global loss of forests could make a major contribution towards balancing the global carbon budget. A 1996 report commissioned by the UN Intergovernmental Panel on Climate Change concluded that the world's forests could store up to 87 billion tonnes of carbon between 1995 and 2050, an amount representing more than 12 per cent of cumulative fossil fuel emissions over the same period. This additional carbon storage, however, would need to come from a reversal of tropical deforestation.

Priceless treasures (top)
It is especially difficult to quantify the value of complex forests ecosystems in economic terms but a 1997 study led by ecologist Robert Costanza estimated that the annual value of such services at $4.7 trillion, roughly 15 per cent of global GNP. Tropical forests were over six times more valuable than temperate and boreal forests, producing on average $2,000 of ecosystem services per hectare.

Studies in the Peruvian Amazon show that whereas the maximum sustainable timber yield for one hectare of plantation forest would be about 30 cubic metres every 20 years, yielding a net value of US$490, fruits and latex could be harvested every year from a protected forest, producing a net income (at fixed prices) of US$8,400 over a 20-year period.

Tegucigalpa, the capital of Honduras, receives 40 per cent of its drinking water from a cloud forest, the La Tigra National Park. Experts estimate that at least US$100 million would be required to replace this service.

Ecotourists at a cloud forest in Costa Rica::� Carsten Rahbek, Still Pictures
Ecotourists at a cloud forest in Costa Rica
� Carsten Rahbek, Still Pictures

In the US alone, revenue generated from tourism in national parks amounts to about $3 billion each year. Studies from the 1980s show that the tourism value of protected areas such as Amboseli National Park in Kenya amounted to US$40 per hectare. The same land, if under agriculture, would be valued at less than US$0.80 per hectare.

According to a recent UN report, undervaluing the economic worth of forests causes governments around the world to lose some $5 billion a year in taxes and royalties. This amount is equal to more than three times the level of official development assistance for financing sustainable forest management (see the UN Forum on Forests report: Economic aspects of forests).

Inadequate tax collection decreases government revenues, poses as a disguised subsidy to producers and reinforces wasteful logging. The problem is typically an indication of improper accounting of forest resources and poor forest valuation. With prices that do not reflect the real value of the products and malfunctioning market mechanisms, illegal economic activities flourish and forest cover continues to decline.

Annual losses from illegal logging exceed $10 billion. The estimated net loss of forests in the 1990s as a whole was 94 million hectares - an area larger than Venezuela.

© People & the Planet 2000 - 2006
Rubber tapper in Jurua Extractive Reserve, Amazon, Brazil. Photo: Greenpeace/Felipe Goifman
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