the summit of mauna kea lies above the tree line, and consists of mostly lava rock and alpine tundra. an area of heavy snowfall, it is inhospitable to vegetation, and is known as the hawaiian tropical high shrublands. growth is restricted here by extremely cold temperatures, a short growing season, low rainfall, and snow during winter months. a lack of soil also retards root growth, makes it difficult to absorb nutrients from the ground, and gives the area a very low water retention capacity.