Páramo can refer to a variety of alpine tundra ecosystems. Some ecologists describe the páramo broadly as "all high, tropical, montane vegetation above the continuous timberline". A more narrow term classifies the páramo according to its regional placement in the northern Andes of South America and adjacent southern Central America. The páramo is the ecosystem of the regions above the continuous forest line, yet below the permanent snowline. It is a "Neotropical high mountain biome with a vegetation composed mainly of giant rosette plants, shrubs and grasses". According to scientists, páramos may be "evolutionary hot spots" and among the fastest evolving regions on Earth.