Deforestation

In many countries, and especially in the developing countries of the southern hemisphere, systematic burning, grazing and cutting of forest-land is carried out in order to provide new land for agricultural or livestock purposes. It is often carried out without factors such as climate and topography having been sufficiently studied and on lands where slope, nature of the soil or other physiographic characteristics clearly indicate that the land involved is suitable only for forest. | Environmental Assessment: Pressure State Response Indicators Policy Pressures and Policy Options

Although this practice may lead to a temporary increase in productivity, there are also many indications that in the long run there is usually a decrease in productivity per unit of surface and that erosion and irreversible soil deterioration often accompany this process.

Forests on which humans and other animals depend heavily take in carbon dioxide gas, provide oxygen and clean the air. Their water holding capacity maintains soil and water levels, preventing disasters such as landslides, floods and droughts. Tropical forests, the most important surviving woodlands, contain about two thirds of all plant and animal species. Tropical plants are the basis for several useful drugs, but vast numbers have not been tested for their medical properties. Tropical forests are also stores of genetic material to feed back into cultivated plants susceptible to disease and pests. At the present rate of deforestation, an estimated 15% of all species could disappear within the next two decades.

Many factors contribute to deforestation: timber production, clearance for agriculture (including livestock production), cutting for firewood and charcoal, fires, droughts, strip mining, pollution, urban development, population pressures and warfare.

It is estimated that the annual rate of deforestation is of the order of 17 million hectares. Other estimates include:

- The Himalayan watershed covering Northern India, Nepal, and Bangladesh had lost 40% of its forest by 1980.
- The USA cleared most of its forests in the 19th century and is still felling trees. In the last decade, logs equivalent to a 600,000 acre forest were shipped outside the US. By the year 2000, timber will be cut nearly twice as fast on national forests as new trees can replace it.
- Costa Rica has lost a third of its forests, loses 60,000 hectares a year and will have none by the 2000.
- Ethiopia had 60% forest cover in 1940, today it has just 2.5%.
- One million Indonesian farmers still use slash and burn techniques.
- Thousands of hectares are being lost due to warfare in Honduras, Nicaragua, El Salvador and Guatemala.
- More than a third of Switzerland's forests are dead or dying from pollution.
- Over 50% of the trees in west Germany are dead or dying.
- The coniferous taiga is one of the last remaining large forest areas in Siberia. In recent years, 25 million tonnes of Siberian timber have been transported westwards annually along the Trans-Siberian railway line and millions of tonnes more to Pacific harbours such as Vladivostok and on to Japan -- part of the new Russian economic expansion. In addition, deliberate fires (to create pasture) and accidental fires consume one million hectares of Siberian forest every year, and air pollution from industry around Lake Baikal is affecting the health of the uncleared forest.

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