Tropical Andes

The uplifting of the Andes Mountains formed an unusual ecosystem on the eastern slope of the range, where the headwaters of the Amazon River system lie. The east-west winds that blow over South America pick up moisture from the humid Amazon basin. When moisture-laden air reaches the Andes, the irregular topography creates several zones of extremely high precipitation. One is in the piedmont and foothills of Ecuador, one of the wettest places in the Amazon watershed thanks to a year-round trade wind flow. Others are the upper part of the Madre de Dios watershed in Peru, including the area around Quincemil, and Bolivia’s tropical Chapare region.

While conservationists often refer to the biological diversity of the Amazon as a whole, the western edge of the watershed — the forests on the eastern slope of the Andes — harbor more species than either the mountains above or the lowlands to the east. Scientists have found that Yasuní National Park, where a controversial oil drilling project is planned, is emblematic of this high diversity. Among the world’s biodiversity “hot spots” — places with a high diversity of species and a high degree of endemism (species found nowhere else on earth) — the tropical Andes region ranks among the most important for conservation. Scientists believe these tropical montane forests have been, and remains, important to maintaining the diversity of life in the Amazonian lowlands, as well.

Many parts of the tropical Andes, however, are under pressure from development projects, including hydroelectric dams, petroleum exploration and production, and highway and pipeline construction. Such projects often result in increased migration to and settlement of once-remote areas, with deforestation and habitat fragmentation that threaten the survival of the species living there.

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