The Valdivian temperate rain forests are a temperate broadleaf and mixed-forest ecoregion located on the west coast of southern South America, lying mostly in Chile and extending into a small part of Argentina. It is part of the Neotropic ecozone. The forests are named after the city of Valdivia. The Valdivian termperate rainforests are characterized by their dense understories of bamboos and ferns and for being mostly dominated by evergreen angiosperm trees albeit deciduous and conifer trees are also common.
The Valdivian temperate rain forests comprise a relatively narrow coastal strip between the Pacific Ocean to the west, and the southern Andes Mountains to the east, from roughly 37° to 48° south latitude. North of 42°, the Chilean coastal range runs along the coast, and the north-south running Chilean Central Valley lies between the coastal range and the Andes. South of 42°, the coast range continues as a chain of offshore islands, including Chiloé Island and the Chonos Archipelago, while the "Central Valley" is submerged and continues as the Gulf of Corcovado. Much of the ecoregion was covered by the Patagonian Ice Sheet and other glaciers at the peak of the last ice age, which descended from the Andes mountains, and the numerous lakes of the Chilean lakes district in the central part of the ecoregion were originally glacial valleys, while the southern part of the region has many glacier-carved fjords.
To the north the Valdivian forests give way to the Mediterranean forests, woodlands, and scrub of the Chilean Matorral ecoregion. Some few Valdivian forests grows in northern Chile such as that one in Bosque De Fray Jorge National Park as remains of the last glacial maximum. To the south lies the Magellanic Subpolar Forests ecoregion. The temperate Valdivian, Matorral, and Magellanic ecoregions are isolated from the subtropical and tropical forests of northern South America by the Atacama desert north of the Matorral, the Andes mountains, and dry rain-shadow Argentine grasslands east of the Andes. As a result, the temperate forest regions have evolved in relative isolation, with a high degree of endemic species.