Environmental Engineering Reference
In-Depth Information
fertility of the land is low unless it is carefully tended: productivity of crops declined
rapidly once the initial nutrient content was exhausted. Artificial fertilizers are expensive
because of high transport costs in such locations, so peasant farmers could not afford
them and hence the soil fertility declined. Even unsuitable crops were supplied to the
settlers which did not grow well. Mining presents an added problem in some areas
(Figure 1). Recently the Brazilian currency has become more stable after years of
inflation. Land is therefore no longer such an important speculative asset, so the capital
cost of purchase has to be recouped by means of production on the land through timber
sales or agriculture. The Brazilian government is attempting to control the amount of
deforestation yet at the same time provide an adequate economy for those living in the
area. It seems inevitable that further demands will be made on this valuable resource.
For a variety of reasons we find that there is great pressure on the tropical rain forests
of the world. Their area is declining rapidly. Many ecologists believe that early in the
twenty-first century only two significant areas of tropical rain forest will remain - in
western Amazonia and in central Zaire.
Figure 1
Major development programmes in
Brazilian Amazonia. Source: After Goodman and
Hall (1990).
