Sustainability

Deforestation and consequences

Farming also means exploitation of forests. There are many reasons for deforestation: timber trade, exploitation of ore deposits, urbanisation and use of land as farmland or pasture.
Unfortunately, for many poor countries, high-quality wood from the forests is one of the few assets available to develop their economy. And often we see indiscriminate deforestation being carried out, which causes huge damages to the environment and to mankind.
 For a sustainable use of the forestry resources, all the advantages and drawbacks should at least be assessed before pulling down a forest. Then, if one decides to pull it down, one should consider replanting either the same area or other areas, so that the total amount of forests on Earth does not change with time.
The effects of the loss of whole forests are particularly harmful and involve, among other things:

• loss of biodiversity. For instance, the Tropical forest (one of the most at risk), that contains over two thirds of the animal and vegetal species of our planet, is a huge reservoir of genetic diversity, which can be used to obtain new, more productive or better-quality crops and active agents for new drugs.
• negative effects on the soil. Once the vegetal coating has been removed, the soil becomes less fertile and more vulnerable to the eroding action of winds and water.
• increased concentration of carbon dioxide in the atmosphere. Through the photosynthesis, the forest is a natural reservoir for the absorption of atmospheric carbon dioxide (see the Greenhouse Effect under Atmosphere);
• repercussions on the water cycle and risk of desertification in some areas;
• negative and often irreversible social effects for the indigenous communities that live on the products of forest ecosystems. 

The destruction of forests, especially Tropical forests, has been attached “global” importance over the last few decades because of its indirect effects on the Earth’s climate.
Burning or cutting down trees, leaving them to rotten on the place, has a double effect: on one side, the combustion or decomposition processes release carbon dioxide, while, on the other side, the trees are prevented from taking in carbon dioxide from the atmosphere and releasing oxygen through the photosynthesis. In addition, the soil, deprived of its vegetal coating, reflects the sunrays better, thus further increasing the greenhouse effect. At present, the emissions of carbon dioxide caused by deforestation and changes in the use of the soil have been estimated, even if very approximately, to amount to about 1.6 billion tons of carbon a year, while those caused by combustion are approximately 6 billion.