The cerrado region of east central Brazil and southward is not only the largest savanna biome of South America but also one of the most romanticized of the world's savannas. As in the Old West of North America, the grasslands of Brazil have cowboys who traditionally have used the cerrado for farming and cattle ranching. With everincreasing pressure from agriculture, the cerrado is now under attack in various ways. Extensive fertilization, associated with modern agriculture, planting of trees for timber production, and the introduction of foreign species, especially African grasses, have all begun to change the cerrado. Frequent fires also have taken their toll. The cerrado contains more than ten thousand species of plants, with 44 percent of them endemic. As much as 75 percent of the cerrado has been lost since 1965, and what remains is fragmented.
Anumber of conservation groups are trying to save as much as possible of what remains.
Two other savanna regions farther south are the Pantanal and the Pampas. Although the Pantanal is a savanna, during the rainy season it becomes a wetland and is a haven for aquatic plants. Later, the Pantanal dries out and grasslands appear in place of the water. This unique area is under attack by a variety of human activities, including navigation and artificial drainage projects, mining, agriculture, and urban waste.
The Pampas, like the great prairies that once covered central North America, is composed almost solely of grass. Trees and shrubs grow near bodies of water, but everywhere else grass predominates. Cattle ranching and wheat and corn farming are the primary occupations of the area and are thus the primary threat. Because the area is farther south than the Pantanal, it has a more temperate climate. Pampas grass from this area has been exported as an ornamental plant.
The last major savanna region is the llanos, located at lower elevations in the drainage area of the Orinoco River in Venezuela and Colombia. This area has pronounced wet and dry seasons. At the lowest elevations, treeless grasslands persist after the water from the rainy season subsides. On the higher plains is a scattering of smaller trees. The mauritia palm can also be found here in poorly drained areas.
|
