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The Tundra of North America is a Level I ecoregion of North America designated by the Commission for Environmental Cooperation (CEC) in its North American Environmental Atlas. One of the planet's most recent biomes , a result of the last ice age only 10,000 years ago, the tundra contains unique flora and fauna formed during the last glaciation ...
In physical geography, tundra (/ ˈ t ʌ n d r ə, ˈ t ʊ n-/) is a type of biome where tree growth is hindered by frigid temperatures and short growing seasons. There are three regions and associated types of tundra: Arctic tundra, [ 2 ] alpine tundra , [ 2 ] and Antarctic tundra.
Alpine tundra is a type of natural region or biome that does not contain trees because it is at high elevation, with an associated harsh climate. As the latitude of a location approaches the poles, the threshold elevation for alpine tundra gets lower until it reaches sea level, and alpine tundra merges with polar tundra .
The short (3–4 month) growing season in boreal forests is sustained by greater levels of rainfall than the tundra receives (between 30 and 85 cm or 12 and 33 in per year). This biome is dominated by closed canopy forests of evergreen conifers, especially spruces, fir, pine and tamarack with some diffuse-porous hardwoods.
The term tundra comes through Russian тундра from the Kildin Sami word tūndâr "uplands," "treeless mountain tract." [15] There are three types of tundra: Arctic tundra, [16] alpine tundra, [16] and Antarctic tundra [17] In tundra, the vegetation is composed of dwarf shrubs, sedges and grasses, mosses, and lichens. Scattered trees grow ...
Formation of deep and bottom waters: the polar areas are the source of ocean deep and bottom cold waters. Due to the sinking of cold and dense saline waters near Greenland, and at the Antarctic Convergence, among other sites, the global ocean circulation is maintained. [4] Models predict a latitudinal effect in response to climate change.
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Marine ecosystems are important sources of ecosystem services and food and jobs for significant portions of the global population. Human uses of marine ecosystems and pollution in marine ecosystems are significantly threats to the stability of these ecosystems.