Southwestern Amazonian moist forests
The Southwestern Amazonian Moist Forests (a Global 200 Ecoregion - SWA G200), contains some of the richest and largest tracts of intact tropical rainforest found in the entire Amazon basin. These forests are the habitat of emblematic species like the jaguar and harpy eagle, highly threatened in other Amazonian regions, dozens of indigenous groups, some of whom have not been contacted by Western civilization, and scattered populations of traditional Brazil nut gatherers and rubber tappers. In spite of its relative isolation, the SWA G200 forests are threatened by the opening and paving of roads that provide access to a growing population of small farmers, oil and gas exploration, as well as large-scale cattle ranching and agribusiness.
Covering 2,093,811 km² of northern Bolivia, southeastern Peru and western and central Brazil, these forests still contain some of the largest tracts of intact tropical rainforest within the entire Amazon basin. Reaching into the foothills of the Andes, the Southwestern Amazonian Moist Forests are influenced by pre-montane conditions that produce diverse climatic and edaphic conditions. The high rainfall, complex topography, and influence of southern temperate winds produce a mosaic of habitats and ecosystems within the lowland tropical forest, contributing to the overall high levels of biodiversity. Such conditions contribute to the formation of an ecologically unique southwestern arc of lowland tropical forests, harboring some of the richest and most intact forest communities on Earth.
The large expanses of relatively undisturbed habitat provide refuge for many species that are highly threatened elsewhere: jaguar (Panthera onca), Harpy eagle (Harpia harpyia), the giant river otter (Pteronura brasiliensis), black caiman (Melanosuchus niger), white-lipped peccary (Tayassu tajacu) and several species of macaws (Ara spp.), guans (Cracidae), and curassows (Crax spp.). While largely understudied biologically, various inventories demonstrate that the region has some of the highest recorded species diversity index in the world for plants, birds, fish, and butterflies. Many of these species are endemic to the Southwestern Amazonian Moist Forests or are no longer found in other regions due to hunting pressure, destruction of intact forest communities, and expansion of “development” programs.
Recent decades have seen the development of the Southwestern Amazon lowland, with the opening of the Brazilian frontier to slash and burn agriculture and large-scale ranching funded by the governments to promote the development of this region and relieve the pressure of the growing populations of small farmers in the northeast and south of Brazil. In addition, colonists from the poor Andean communities of Peru and Bolivia have settled in the lowlands, repeating the process of overexploitation of resources that were eventually depleted in their abandoned highland communities. A network of roads to promote these migrations, as well as allow access to high value woods, oil, gas, and forest resources (especially Brazil nuts and rubber), have increased the colonization of the lowland forests and added stress to the ecological systems dependent on the decreasing area of intact and closed-canopy forests. Decreased rainfall, due primarily to local deforestation and increased human presence, has increased the opportunity for extensive forest fires, having reached a high in the dry season of 1999 as millions of hectares in Rondonia and Acre (Brazil) were engulfed by flames. Tourism, while an opportunity for conservation, is also proving to be a threat to the fragile ecosystems of the Tambopata-Candamo region along the Madre de Dios River basin, and along the Beni River in Bolivia (Rurrenabaque).
The Southwestern Amazonian Moist Forests Global 200 Ecoregion is around 209,381,146 ha and encompasses four ecoregions: Southwest Amazon moist forests, Juruá-Purus moist forests, Purus-Madeira moist forests, and Madeira-Tapajós moist forests.