Highlands ecoregion. This ecoregion has abundant precipitation; an average of of precipitation falls each year at Spirit Lake. This precipitation supported dense forest up to , with western hemlock, Douglas fir, and western redcedar. Above this, this forest was dominated by Pacific silver fir up to . Finally, below treeline, the forest consisted of mountain hemlock, Pacific silver fir and Alaska yellow cedar. Large mammals included Roosevelt elk, black-tailed deer, American black bear, and mountain lion. The treeline at Mount St. Helens was unusually low, at about , the result of prior volcanic disturbance of the forest, as the treeline was thought to be moving up the slopes before the eruption. Alpine meadows were uncommon at Mount St. Helens. Mountain goats inhabited higher elevations of the peak, although their population was eliminated by the 1980 eruption. Ecological disturbance caused by eruption The eruption of Mount St. Helens has been subject to more ecological study than has any other eruption, because research into disturbance commenced immediately after the eruption and because the eruption did not sterilize the immediate area. More than half of the papers on ecological response to volcanic eruption originated from studies of Mount St. Helens. Perhaps the most important ecological concept originating from the study of Mount St. Helens is the biological legacy. Biological legacies are the survivors of catastrophic disturbance; they can either be alive (e.g., plants that survive ashfall or pyroclastic flow), organic debris, or biotic patterns remaining from before the disturbance. These biological legacies highly influence the reestablishment of the post-disturbance ecology. Human history Importance to indigenous tribes Native American lore contains numerous stories to explain the eruptions of Mount St. Helens and other Cascade volcanoes. The best known of these is the Bridge of the Gods story told by the Klickitat people. In the story, the chief of all the gods and his two sons, Pahto (also called Klickitat) and Wy'east, traveled down the Columbia River from the Far North in search for a suitable area to settle. They came upon an area that is now called The Dalles and thought they had never seen a land so beautiful. The sons quarreled over the land, so to solve the dispute their father shot two arrows from his mighty bow – one to the north and the other to the south. Pahto followed the arrow to the north and settled there while Wy'east did the