The Patagonian Realm comprises much of southern and south-western South America along with the Galápagos Islands, Falkland Islands, Juan Fernández Islands, and a few smaller offshore islands. Biogeographically speaking it has obvious affinities to the Neotropical Realm, with which it has traditionally been included, but differs in a number of significant ways owing to its separation by the Andes Mountains. Notably dry for the most part, it ranges from tropical in the north to subpolar in the south. Indeed, southern South America lies nearer to Antarctica than does any other continent, and these areas are therefore often bitterly cold, with glaciers covering the mountains and mists and clouds often sweeping around them. But the microclimates are even more various, owing to differences in altitude and temperatures south of 40°S. latitude. Temperate deciduous forests, arid brushlands, deserts, steppes, and sub-Antarctic moors are the major vegetation types. As one moves south from Chile to the region south of the Strait of Magellan the vegetation changes from forests consisting of many trees covered with epiphytes and lianas to areas where the tree species are few, with half of the forests being composed of southern beeches (Nothofagus). The fauna diminishes in the same way. Large areas of Patagonia once consisted of rich temperate grasslands, but have declined considerably due to overgrazing of cattle. Here the vegetation has disappeared over large areas, erosion has set in, and dust fills the air.