South America : human influences on vegetation

Human activity has transformed the original vegetation cover to a large extent throughout South America, particularly in forested areas. The forests of eastern Brazil were ravaged in the process of clearing the ground for crops, especially sugarcane. The araucaria forests in the southern states of Brazil have been rapidly vanishing, as they have been exploited for timber. The slopes of the Andes are so severely deforested that it is not apparent that they once were covered with trees. In the Amazon region, hundreds of square miles of tropical rain forest are cut annually, and the forest no longer is the enormous inviolate mass it once was. In Patagonia the practice of burning to convert remaining patches of forest into pasture steadily increases. Animal herders have severely damaged grasslands through overgrazing, from the Venezuelan Llanos through the high Andes, to Tierra del Fuego. The destruction of habitats continues to accelerate throughout the continent, despite the growing concern of those favouring conservation.

Subantarctic rain forests

Temperate rain forests—similar to those found in British Columbia and in the northwestern United States—grow in southern Chile at low and moderate altitudes, thanks to abundant rainfall. The most typical trees belong to the genus Nothofagus (beech trees found in the cooler parts of the Southern Hemisphere), the northern species of which are evergreen and the southern species deciduous. Various conifers, notably the alerce and araucarias, mingle with the leafy trees. A dense undergrowth of shrubs, lianas, bamboos, ferns, mosses, and epiphytes grow in the northern districts but disappear toward latitude 49° S. In southern Chilean Patagonia, forests consist of twisted, creeping trees merging into a kind of heath.

Mountain vegetation

In the high Andes, a temperate zone extends from the upper limit of the subtropical rain forest (about 6,000 feet) up to the lower limit of the Andean meadows, at an altitude of about 11,000 feet in Ecuador and Peru. This zone is very humid on the Amazonian side because of rising air, where both the epiphytes and the undergrowth are dense, creating a cloud forest.

The upper zones have a peculiar vegetation that touches the snow line. In the wet northern Andes in Colombia and Ecuador, Alpine meadows called páramo consist of grasses and other herbaceous plants, often with bright flowers; these are surmounted by taller plants, especially the showy frailejones (Espeletia), which grow 15 to 20 feet high and are crowned by large bouquets of long hairy leaves.

Plants of mountains. horizonsunlimited.com

In the south, páramo vegetation merges with that of the high plateaus, notably the tola, a tough wind-resistant shrub, in the Altiplano of southeastern Peru and western Bolivia. Typical vegetation consists of rough grasses, between which grow a variety of herbaceous, cushion, and rosette plants, shrubs, and cacti. Vegetation extends to the limit of permanent snow but becomes scarce at higher elevations, where soil is often barren. Britannica