Smaller animals include marmots, pocket gophers, and ground squirrels. It is characterized by low-growing plants such as moss, lichens, and short shrubs. Cold winds and blowing snow favor low-growing, protected plants. Musk-oxen, wolves, some bears, and lemmings live in this biome throughout the year. The majority of the ground cover stays frozen throughout the year, with only the top 2 to 3 feet thawing out during the short, four-month spring and summer period.
Tundra is found near the poles.
Mountains are very complex areas. Drastic changes in elevation over a short distance impact rainfall, soil types, and temperature. Because the type of ecosystem found in an area is dependent on these abiotic factors, a mountain can contain several radically different types of ecosystems in a relatively small area. Ecologists refer to mountains as areas of complex zonation because of the many ecosystems found. For instance, temperate deciduous forest can be found at the base of a mountain.