The Canadian Arctic tundra is a biogeographic designation for Northern Canada's terrain generally lying north of the tree line or boreal forest,The tundra biome at the University of CaliforniaCanada's Arctic Tundra at Hinterland Who's WhoThe Arctic: Environmental Issues at the Parliament of Canada that corresponds with the Scandinavian Alpine tundra to the east and the Siberian Arctic tundra to the west inside the circumpolar tundra belt of the Northern Hemisphere.
Canada's northern territories encompass a total area of , 26% of the country's landmass that includes the Arctic coastal tundra, the Arctic Lowlands and the Innuitian Region in the High Arctic. Tundra terrain accounts for approximately in Yukon, the Northwest Territories, in Nunavut, north-eastern Manitoba, northern Ontario, northern Quebec, northern Labrador and the islands of the Arctic Archipelago, of which Baffin Island with is the largest.
Canada's tundra is characterized by extreme climatic conditions with year-round frozen grounds, long and cold winters, a very short growing season and low precipitation rates.
The Canadian Arctic tundra is the traditional home of indigenous peoples, predominately Inuit, who for most of their settlement history occupied the coastal areas of Nunavut, Nunavik (northern Quebec), Nunatsiavut (northern Labrador), the Northwest Territories and formerly in Yukon. Population numbers remain very moderate for the entire region and as of 2006 around 50% of the inhabitants are of indigenous descent.
Changing climate, recorded and documented over several decades has already caused noticeable regional environmental instability and threatened or endangered a number of species.
Tundra is predominant in: Canada's northern mainland - the terrain north of the arboreal taiga belt, east and west of Hudson Bay the islands of the Arctic Archipelago - bordered by the Beaufort Sea, Hudson Bay and Baffin Bay
Coordinates
Geographic extremes for Canada's Arctic tundra North - South maximum latitudinal extent North: Cape Columbia to South: Flaherty Island East - West maximum longitudinal extent East: Baffin Island to West: Herschel Island
Mainland
The northern mainland terrains, the Arctic coastal tundra and the Arctic Lowlands connect with the Alaskan coastal plain to the west and adjoin the coastal tundra of Greenland to the east. Countless lakes, rivers, deltas, marine straits and an extensive, rugged coastline comprise this complex and interdependent patchwork of terrestrial and marine habitats.
Arctic archipelago
The Arctic Archipelago is subdivided into three biogeographical regions with distinctive floral and faunal communities:
Arctic Cordillera The Arctic Cordillera is a large, deeply dissected chain of mountain ranges extending along the northeastern flank of the Arctic Archipelago from Ellesmere Island to the north-easternmost part of the Labrador Peninsula in northern Labrador and northern Quebec. The range is characterized by high glaciated peaks and ice caps, that includes Northern Canada's highest point at Barbeau Peak, reaching . The high elevations of this ecoregion is a Polar desert as lower elevated plains are dominated by patches of lichen and moss.
Northern Arctic It contains the northern edges of the Northwest Territories, Nunavut and much of the island plateaus, such as the Parry and Lancaster island plateaus. Extending over most of the archipelago, this is the coldest and driest part of Canada. Lichens and herbs dominate in dry tundra interspersed with wetland species.
Southern Arctic It comprises areas on the mainland - the southern half of Nunavut and the Northwest territories and stretches down into Quebec, Hudson Bay, the Ungava Peninsula and includes the Aberdeen and Amundsen Plains. Dominant features are hills and plains, ponds and lakes that allow growth of low shrubs mixed with herbs, lichens, and cotton-grass. Stunted Krummholz trees grow along the major river valleys.
For almost a million square kilometres, the pattern of habitats in the Southern Arctic is the same: sprawling shrublands, wet sedge meadows, and cold, clear lakes. Superimposed on this pattern are the fascinating shapes and textures created by intense frost action in the soil.
The Southern Arctic is the region of transition from the treeless Arctic tundra to the conifer forests. dwarf birch and Arctic willow are among the common shrub species, along with heaths, herbaceous plants, and lichens. Where nutrients and moisture are available along the rivers and streams, scattered clumps of stunted spruce trees grow. Sedges and mosses thrive in the wetlands of the lowland areas of this ecoregion and provide nesting sites for birds. Vegetation is most dense in sheltered areas and depressions, where there is less wind and more moisture.
Arctic forest tundra transition zone
Canada's long tree line is a spatially inconsistent structure. Often several alternating vegetation patches are found in a Vegetation Tension Zone. The entire range greatly varies in width and widens markedly in the east, particularly in the region of the Hudson Bay. Local soil, elevation and drainage quality are influential factors for the growth of the transition, some scholars also pointed to "differences in albedo and snow retention caused by the presence of certain coniferous trees".
Geological setting
Northern Canada's present physiognomy formed beginning around 750 to 600 million years ago by the breakup and subsequent rifting of the supercontinent Rodinia. The subsequent geological sequence has since created a recent physiography that divides into the regions listed below.
Canadian Shield Interior Platform Appalachian Orogen Innuitian Orogeny Cordillera and Western Canada Sedimentary Basin
Canada's tundra runs more or less over all physiographic divisions except the Appalachian Orogen. As these formations are of deep tectonic nature they do not necessarily constitute the structure and material found on the surface, are observable elevated mountain ranges or orogenic belts. Large areas of the Canadian Shield - the ancient geological core of the North American continental plate are buried under sedimentary rocks of the Interior Platform. Repeated glaciations have had a profound impact on shaping land forms and determining drainage patterns.
Surface geology and permafrost
Permafrost, the dominant natural phenomenon of the tundra is of fundamental significance for this unique ecosystem, as it commands the tundra's climate, wild life, ecology, drainage and soils. Definition: "Permafrost is soil, rock or sediment that is frozen for more than two consecutive years."
Recognized classification for the Northern Hemisphere regions in which permafrost occurs, on approximately 25% of the land area ().
continuous permafrost (underlying 90 to 100% of the landscape) discontinuous permafrost (50 to 90%) sporadic permafrost (0 to 50%)
In the discontinuous and sporadic zones permafrost distribution is complex and patchy, and permafrost-free terrain is common. The depth of permafrost varies from less than one meter to more than . Patterned ground - large polygonal ground patterns and ice wedges caused by frost over a long period of time are common throughout the region except for areas of solid bedrock.
Surface
The Arctic Cordillera peaks at over , topped with extensive glaciers. There are nunataks, ice fields and deeply cut valleys, a rugged coastline with long winding fjords and large areas of exposed bedrock. Lowland soils consist of loose rocky, sandy, colluvial and morainal material.
The lowland plains of the western mainland Arctic are covered with Pleistocene materials and outcrops of Paleozoic and Mesozoic sediments. East of the Prince of Wales and Somerset islands, Precambrian granite bedrock surfaces.
The Southern Arctic sits on Precambrian granitic bedrock outcrops, followed in the west by Cretaceous shales from the Great Bear Lake to the Firth River, Yukon. The undulating landscape has innumerable lakes, ponds and wetlands and stratified sediments up to long. Seasonally frozen top layers vary in depth as differences in moisture give rise to a variety of land forms and habitats.
Soils
The active top layer of most southern and central soil profiles is only seasonally frozen, contains water, gases and nutrients, its depth varies depending on material, vegetative cover and the local temperature. Permafrost acts "through physical and chemical processes in the top layer which operate as thermal and hydrological gradients". Soils of the southern terrain consist of various glacial deposits. Finely-textured marine sediments dominate the soils of the coastal regions.
Climate and biotope
Characteristics
Harsh environmental and weather conditions, slow growth and decomposition, poor soils, sparse resources and nutrients, low variety of land forms favour highly adapted and migratory life forms. Diversity of species is only seasonal and habitat sustainability is usually confined to brief periods of appropriate conditions. Hundreds of species of flowering plants are documented. Yet these are organisms with a short life cycle that reproduce by budding and division rather than by interaction with insects. The mid-summer growing season with up to 24 hours of sun lasts for 50 to 60 days. The average precipitation is per season. The tundra classifies as a desert due to low precipitation rates, yet permafrost causes even lower degrees of drainage and evaporation and as a result the ground, lakes and glaciers hold large quantities of fresh water.
Prolonged periods without sun light, frozen ground and strong winds also prevent substantial tree growth. Lichen, uniquely adapted, and does not rely on roots and soil for growth is one of the most notable, widespread and enduring organisms of the tundra. A symbiotic life form with a photobiont (algae or cyanobacteria) living among the filaments of a fungus where it benefits from moisture, elementary nutrients and is protected from the environment. The photobiont's photosynthetic processes in turn generate organic carbon sugars that feed the fungus.
Temperatures
Midsummer shade temperatures peak at on the continent beyond the Arctic Circle, and in winter the temperature drops below . In the Arctic Archipelago average midsummer temperatures are lower than . Differences between soil surface and air temperatures can be considerable and are largely influenced by direct insolation and wind velocity.
Wildlife
Pleistocene migrations
During the Pleistocene, Beringia a land bridge existed (from 70,000 to 60,000 and 30,000 to 11,000 years ago) between Alaska and Siberia. This corridor offered an opportunity for the interchange of fauna between Asia and the Americas. At the same time, these land masses provided ice-free terrain for mammals on which they could settle and reproduce - called Wisconsin refuge.
Beringia is also one of the main migration routes of paleo-humans into North America including the Paleo-Eskimo communities of Alaska, Greenland and the Canadian Arctic.
Flora
The flora of the Canadian Arctic is characterized by low species diversity, low endemism and high resistance towards introduced species, attributed to more recent glaciation, in comparison to other Arctic regions, such as the Siberian tundra. The southern edge of the Canadian Arctic tundra is met by an arboreal tree line - the Arctic forest-tundra transition zone.
In order to adapt to the extreme conditions of the Arctic, plants have: reduced leaf size to minimize water loss to wind fuzzy hair-like structures or alternatively grow in mats to protect themselves from snow and wind damage often extensive root systems to store nutrients for the long and harsh winter months.