Other factors like soil development, movement of soil by animals, and drainage determine vegetation community distribution. Alpine tundra of Niwot Ridge,Colorado, USA . Solifluction terraces with willow growing on top and to the back are visible in the center of the photograph. Late lying snow patches keep conditions moist to permit willow growth. Reaching several feet high, willows are covered by snow to protect the overwintering buds.
Willows are the tallest of any species in the alpine tundra.
These colorful rock gardens are exposed to the rigors of the wind. Wind removes snow throughout the season subjecting the plants to desiccation. Low-lying mats and cushion plants nestle against the the rocky surface.