Atlantic Forest

The Atlantic Forest (Portuguese: Mata Atlântica) is a region of tropical and subtropical moist forest, tropical dry forest, tropical savanna, semi-deciduous forest and mangrove forests which extends along the Atlantic coast of Brazil from Rio Grande do Norte state in the north to Rio Grande do Sul state in the south, and inland as far as Paraguay and the Misiones Province of Argentina. The Atlantic Forest is characterized by a high species diversity and endemism. It was the first environment that the Portuguese conquerors encountered over 500 years ago when it was thought to have had an area of 1,000,000 to 1,500,000 km2 (390,000 to 580,000 sq mi) and stretching an unknown distance inland. Currently, the Atlantic Forest spans over 4,000 km2 (1,500 sq mi) along the coast of Brazil and in a small part of Paraguay and Argentina. In Argentina, it is known as Selva Atlántica.

The Atlantic Forest region includes forests of several variations:

• Restinga is a forest type that grows on stabilized coastal dunes. Restinga Forests are generally closed canopy short forests with tree density. Open Restinga is an open, savanna-like formation with scattered clumps of small trees and shrubs and an extensive layer of herbs, grasses, and sedges.
• Tropical moist forests are forests that receive more than 2000 mm of rain a year. This includes Lowland Tropical Moist Forests, Submontane Tropical Moist Forest, and Montane Tropical Moist Forest.
• Tabuleiro forests are found over very moist clay soils and Tabuleiro Savannas occur over faster-draining sand soils. These are humid areas that rely on water vapor from the ocean.
• Further inland are the Atlantic dry forests or seasonal forests, which form a transition between the arid Caatinga to the northeast and the Cerrado savannas to the east. These forests are lower in stature; more open, with high abundance of deciduous trees and lower diversity when compared to tropical moist forests. These forests have between 700-1600 mm of precipitation annually with a distinct dry season. This includes Deciduous and Semideciduous Seasonal Forest each with their own lowland and montane regions.
• Montane moist forests are higher altitude wet forests across mountains and plateaus of southern Brazil.
• Shrubby montane savannas occur at the highest elevations, also called Campo rupestre.

The Atlantic Forest is unusual in that it extends as a true tropical rainforest to latitudes as high as 24°S. This is because the trade winds produce precipitation throughout the southern winter. In fact, the northern Zona da Mata of northeastern Brazil receives much more rainfall between May and August than during the southern summer.

The Atlantic Forest is now designated a World Biosphere Reserve, which contains a large number of highly endangered species. The enormous biodiversity of the Atlantic Forest results in part from the wide range of latitude it covers, its variations in altitude, its diverse climatic regimes as well as the geological and climatic history of the whole region. The Atlantic Forest is isolated from is neighboring large South American forests: The Amazon Region and the Andean Forest. The open vegetation of the Caatinga and the Cerrado separate it from the Amazon, and the dry vegetation of the central depressions of the Chaco separate it from the Andean Forest. This isolation has resulted in an evolution of numerous endemic species, such as lion tamarins, woolly spider monkey, and marmosets.

During glacial periods in the Pleistocene, the Atlantic Forest is known to have shrunk to extremely small fragmented refugias in highly sheltered gullies, being separated by areas of dry forest or semi-deserts known as caatingas. Some maps even suggest the forest actually survived in moist pockets well away from the coastline, where its endemic rainforest species mixed with much cooler-climate species. Unlike refugia for equatorial rainforests, the refuges for the Atlantic Forest have never been the product of detailed identification.