Ecosystems

The lungs of the world

For over one hundred million years, the tropical forest has played a crucial role: it serves an extraordinary and relentless biological and geopedological function which is absolutely necessary for men and animals to survive. Firstly, the trees protect the ground from the erosion of the rain and have a role in the earth-air circulation of water. Transpiration is a way to transfer water from the ground to the air: this occurs through the pores of the leaves, the stomas. In a forest with a thick vegetal covering, more than 80% of water leaves the ground through transpiration. The water vapour thus produced by the tropical forest and dispersed in the air keeps the climate wet and promotes the growth of vegetation. In addition, the trees take carbon dioxide, one of the gases responsible for the greenhouse effect, from the air. Through the photosynthesis of the chlorophyll, the plants, by using energy from sunlight, fix carbon dioxide and release oxygen. Another function of this ecosystem is that it acts as a laboratory for the development of species. Many varieties of plants, shrubs, mosses, fungi, slowly develop to occupy the small interstices of this ecosystem. This results in a great diversification. For instance, this forest has over 300 species of birds and its flora is equally plentiful. And moreover, the Amazonian basin is the largest freshwater reserve on earth (approximately one fifth of the freshwater existing on earth).