Permafrost is a common feature of the arctic tundra climate and biome. Permafrost refers to permanently frozen ground. Actually, the ground has two layers which freeze. Beneath the active layer is the inactive layer which stays frozen throughout the year. Permafrost creates a barrier to the root development.
Larger trees can grow along better drained river valleys where the depth to permafrost is greater.
The annual freezing and thawing disrupts root systems inhibiting the growth of very tall vegetation. Tilted poles on Northway access road, Yukon region Alaska . Permafrost creates an engineering nightmare for the construction of buildings and other structures. You can see in the photo to the left how telephone poles have been tilted from the heaving of the surface during freezing and thawing. Musk Ox of the Alaskan arctic tundra.