Immediately to the south is the evergreen Magellanic rainforest, probably associated with the increased precipitation, the greater altitude and an improvement in the drainage. The characteristic species is "Nothofagus betuloides" (Coihue of Magallanes), forming pure communities in sectors of greater altitude or coasts exposed to the wind. The south portion of the island, surrounding Lakes Navarino and Windhond, and the territories of the southern coast, have a vegetation of Magellanic moorland. This includes a series of vegetal communities, the Esfagnosa Tundra ("Sphagnum magellanicum") and the Pulvinada Tundra ("Donatia fascicularis" - "Astelia pumila"). At higher altitudes, the terrain is Andean Desert, which lacks trees or tall shrubs and is less than 30% covered by vegetation. Like much of surrounding Tierra del Fuego, Navarino Island has been severely affected by invasive beavers. The Canadian beavers were introduced to Tierra del Fuego in the 1940s by the Argentinian government in an effort to kickstart a fur trade in the area. With no natural predators, the beavers quickly spread to neighbouring islands. Because the trees in Tierra del Fuego and Isla Navarino do not have any natural defences, they are unable to recover once felled by beavers. Researchers from the University of North Texas, when studying Navarino Island found that the slow-moving water behind beaver damns has attracted two further invasive species to the Island, muskrat and mink. While the mink prey on the muskrats, they also feed on native geese and duck, leading to what they term an "invasive meltdown process". Cultural historical sites are Bahia Wulaia and the English Mission of Douglas Creek. The large Stirling House, an iron Meccano construction brought in 1869 from England by the Anglican English missionaries, used to be in Ushuaia. It was moved to Tekenika Bay, and then was installed for mission use at Douglas Creek. In the Yahgan cemetery at Mejillones Bay, tombs dating from the first half of the 20th century show elements of religious syncretism. Villa Ukika is a district of Puerto Williams where the last few Yaghan people live. Puerto Navarino, a fishing port for king crabs, has wooden buildings, constructed mainly in the 1930s.