An isolated evolutionary island
The Valdivian Temperate Rainforest is a biogeographic island. For millions of years, it has been separated from other South American forests by the Atacama Desert to the north, the Andes mountains to the east, and the Pacific Ocean to the west. This long isolation, which began with the breakup of the supercontinent Gondwana, has allowed a unique collection of life to evolve. Many of its plant families and genera are shared not with the nearby Amazon, but with the distant temperate rainforests of Australia, Tasmania, and New Zealand.
This forest contains Gondwanan flora. It contains southern beeches (Nothofagus) and conifers like podocarps, both of which are also found across the Pacific in Oceania. The dominant tree in many areas is the Alerce (Fitzroya cupressoides), a massive conifer and the largest tree species in South America. These trees are exceptionally long-lived; one individual in Alerce Costero National Park, known as the "Gran Abuelo" (Great-Grandfather), is estimated to be 5,484 years old, potentially making it the world's oldest living tree. Alerce trees can grow to heights of over 60 meters (200 feet) with trunk diameters up to 5 meters (16 feet). The forest receives immense rainfall, from 1,000 mm in the north to over 6,000 mm per year in some southern areas.
Sanctuary for living fossils
The forest's isolation has also shaped its animal life. It is a refuge for creatures whose closest relatives are continents away. The most notable example is the monito del monte (Dromiciops gliroides), a small, nocturnal marsupial. It is the only surviving species of the ancient order Microbiotheria and is more closely related to Australian marsupials like kangaroos than to any other marsupial in the Americas. This is a living fossil.
Other unique mammals have evolved here. The southern pudú (Pudu puda) is the world's second-smallest deer, standing just 35 to 45 cm (14 to 18 inches) at the shoulder and weighing between 6.5 and 13.5 kg. The dense bamboo thickets provide it with excellent cover from predators. The forest is also home to the kodkod (Leopardus guigna), the smallest cat in the Americas, and Darwin's fox (Lycalopex fulvipes), an endangered canid first identified by Charles Darwin in 1834. The region has exceptionally high rates of endemism; about 45% of all vertebrates and 76% of amphibians are found nowhere else on Earth.