the alaska range is a mountainous expanse running through the entire park, strongly influencing the park's ecosystems. vegetation in the park depends on the altitude. the treeline is at , causing most of the park to be a vast expanse of tundra. in the lowland areas of the park, such as the western sections surrounding wonder lake, spruces and willows dominate the forest. most trees and shrubs do not reach full size, due to unfavorable climate and thin soils. there are three types of forest in the park: from lowest to highest, they are low brush bog, bottomland spruce-poplar forest, upland spruce-hardwood forest. the forest grows in a mosaic, due to periodic fires.