Home >> Science & Nature >> Nature

Biotic & Abiotic Characteristics of Tundras

Tundras, the coldest of biomes, cover approximately 20 percent of Earth's surface. There are two types of tundra, arctic and alpine. The former surrounds the North Pole, while the latter occurs at the tops of mountains. In both cases, extreme conditions limit biodiversity, though a number of species have developed adaptations that enable them to survive in the tundra's harsh, icy environment.

Soil
- Arctic tundra is distinguished from alpine tundra by permafrost, a layer of subsoil that remains frozen year-round. Permafrost consists mainly of gravel and dead plant matter. In some regions, such as the Alaska Arctic Plain, the permafrost layer can be more than 2,000 feet thick. The soil above the permafrost, known as the active layer, melts during the summer to form bogs and lakes that teem with life. Drainage occurs in alpine tundra, where there is no permafrost.
Climate
- The average temperature of tundra ranges from 10 to 20 degrees Fahrenheit, according to National Geographic. In the winter, temperatures can plummet to -76 degrees F. The arctic tundra's summer lasts approximately two months, during which there is sunlight 24 hours a day and the average temperature is between 40 and 50 degrees F. In some regions, temperatures peak at around 77 degrees. The growing season of alpine tundra is longer, lasting approximately 180 days, though temperatures are generally below the freezing point at night. Tundras receive from 6 to 10 inches of precipitation a year.
Fauna
- Many animal species in the arctic tundra migrate to the region during the growing season and depart for warmer areas when food becomes scarce. Year-round residents include polar bears and musk oxen, which have thick coats. The latter also has short legs and a short tail that reduce the loss of body heat. Other tundra mammals include hares, lemmings and caribou. Mountain goats, pikas, sheep and elk are found in alpine tundra ecosystems.
  
  In addition, arctic tundra supports a number of avian species, including snowy owls, terns, falcons and ravens. Alpine tundra's bird population consists of mostly grouse-like species.
  
  Butterflies and grasshoppers also occur in most tundras. Few cold-blooded animals like reptiles and amphibians can survive in the tundra.
Flora
- Though no trees can live in the tundra's conditions, the arctic variety supports approximately 1,700 plant species, according to the University of California Museum of Paleontology. Tundra vegetation generally grows close to the ground and lacks deep roots. Examples include lichen, reindeer mosses and liverworts.
  
  With a longer growing season and no permafrost, alpine tundra supports species similar to those found in the arctic, in addition to taller plants, such as dwarf trees and heaths. Because the growing season is relatively short, most tundra plants reproduce by budding and division instead of sexually.

Nature