The rate of deforestation in Africa is a cause for extreme concern: around four million hectares of forest are destroyed each year, to the extent that 45 per cent of its original forest cover has disappeared.
Commercial logging, clearance for agriculture, roads and railways, forest fires, mining and drilling, fuelwood collection and clearance for living space are all intimately connected with deforestation, but it is far from obvious as to which is the worst culprit.
People have been living in and around tropical rain forests for tens of thousands of years, taking what they needed from the wealth of natural resources available without compromising their environment. However, in the last two centuries populations have expanded, requiring more and more space for housing and agriculture. Coupled with the extremely lucrative international timber trade in recent years, this has brought about an unparalleled degradation of the rain forests.
The two most commonly cited causes of deforestation are shifting cultivation and commercial logging. In the past, indigenous peoples have farmed the rain forests, felling trees to allow cultivation of crops and grazing space for animals, and moving on when the soil becomes less fertile. This is no threat to the forests, provided that it is carried out sustainably, and used areas are left to regenerate for long periods before repeating the process. Problems arise when the land is not allowed sufficient time to recover, and intensive farming results in irreversible soil degradation. This is the present situation, due to the needs of the growing population - and some sources identify shifting cultivation as the cause of 70 per cent of the deforestation in Africa.
As with shifting cultivation, if logging is carried out in a controlled way it can be implemented with only minor disturbance to the environment. It is when felling of trees begins to exceed tree production that logging becomes seriously detrimental. Before intensive mechanised logging took over from the use of handsaws, axes and animal power, it could be argued that the timber trade posed little threat to tropical rain forests, but the arrival of chainsaws, tractors, roads and railways had a much greater impact. Previously inaccessible areas have now become prime targets for commercial logging companies, and poor management has led to unprecedented losses.
Other factors such as the felling of trees for charcoal, and clearance for mining and the extraction of oil are considered less damaging than shifting cultivation and commercial logging, but they nonetheless pose a threat to the existence of the tropical rain forests.
To many people living in temperate climates, tropical rain forests are fascinating places, full of mystery and promise, containing some of the most interesting and diverse products nature has to offer. So it would be a disaster if they were to vanish. Once cleared of trees, rain forest topsoil, which can take over a thousand years to accumulate, can be eroded in just one decade. This makes the land unusable, and can in turn lead to disastrous flooding since there is no soil to soak up the rain. But that's not the end of the story.
Forest clearance also leaves human forest dwellers without food or shelter, and leads to the disappearance of ways of life which have existed largely unchanged for thousands of years. However, potentially the most damaging effect of forest clearance is its impact on the planet's climate. We have all heard of the perils of global warming and the greenhouse effect, and it is common knowledge that this is caused mainly be the build-up of carbon dioxide in the atmosphere. Trees and other green plants absorb carbon dioxide and produce oxygen through photosynthesis, whereas animals breathe in oxygen and breathe out carbon dioxide. The destruction of the tropical rain forests would bring about a disastrous imbalance in the amounts of carbon dioxide produced and recycled, leading to a build up in the atmosphere, and increased climate change. Add to this the fact that many of the trees cut down to provide space for agriculture are either burned or left to rot, releasing even more carbon dioxide, and clearly we have a recipe for disaster. The whole of nature is a vast interrelated system which currently exists in a more or less balanced state. Tampering with such important factors as the rain forests could bring about irreversible damage to the world as we know it.
A further consequence of deforestation concerns the scientific possibilities which would be lost with the demise of the tropical rain forests. It is estimated that only a small fraction of the plants and animals living in rain forests have been identified, and some scientists speculate that many of these may hold the keys to finding cures for some of the most deadly diseases known to man. For example, the US National Cancer Institute has catalogued some 3,000 plants with anti-cancer properties, 70 per cent of which are found in tropical forests. Who knows what other secrets the rain forests hold?