Alternative site for the Global ecosystem typology with additional information for ecosystem profiles and indicative maps.
This site is maintained by jrfep
The polar/alpine biome encompasses the extensive Arctic and Antarctic regions as well as high mountainous areas across all continental land masses. Primary productivity is low or very low, strictly seasonal and limited by conditions of extreme cold associated with low insolation and/or high elevation, further exacerbated by desiccating conditions and high velocity winds. Low temperatures limit metabolic activity and define the length of growing seasons. Microbial decomposition is consequently slow, leading to peat accumulation in the most productive ecosystems. Regional and local temperature gradients have major influences on shaping ecosystems within the biome. Standing biomass, for example, is low or very low and varies with the severity of cold and insolation. Microbial life-forms dominate in the coldest systems with perennial snow or ice cover, augmented with crustose lichens, bryophytes and algae on periodically exposed lithic substrates. Forbs, grasses and dwarf shrubs with slow growth rates and long life-spans become increasingly prominent and may develop continuous cover with increasing insolation and warmer conditions. This vegetation cover provides habitat structure and food for vertebrate and invertebrate consumers and their predators. Trophic webs are simple or truncated and populations of larger vertebrates are generally migratory or itinerant. In these warmer cryogenic systems, snow cover is seasonal (except at equatorial latitudes) and insulates plants and animals that lie dormant beneath it during winter and critically during their emergence from dormancy just prior to spring thaw. While dormancy is a common trait, a diverse range of other physiological, behavioural and morphological traits that facilitate cold tolerance are also well represented among the biota.