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The tree line is the edge of a habitat at which trees are capable of growing and beyond which they are not. It is found at high elevations and high latitudes. Beyond the tree line, trees cannot tolerate the environmental conditions (usually low temperatures, extreme snowpack, or associated lack of available moisture).
The Canadian Arctic tundra is a biogeographic designation for Northern Canada's terrain generally lying north of the tree line or boreal forest, [2] [3] [4] 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.
This line, like the arctic tree line, is a natural boundary rather than an artificial one, such as the borders of nations and time zones. It not only separates two hydrological regions, but also separates areas of distinctive marine life and climates.
Another definition of the Arctic, which is popular with ecologists, is the region in the Northern Hemisphere where the average temperature for the warmest month (July) is below 10 °C (50 °F); the northernmost tree line roughly follows the isotherm at the boundary of this region. [7] [8]
Arctic vegetation is largely controlled by the mean temperature in July, the warmest month. Arctic vegetation occurs in the tundra climate, where trees cannot grow.Tundra climate has two boundaries: the snow line, where permanent year-round snow and ice are on the ground, and the tree line, where the climate becomes warm enough for trees to grow. [7]
At the tree line, tree growth is often sparse, stunted, and deformed by wind and cold krummholz (German for "crooked wood"). [26] The tree line often appears well-defined, but it can be a more gradual transition. Trees grow shorter and often at lower densities as they approach tree line, above which they cease to exist. [27]
The underlying soil of this damp Arctic coast is thick, solid permafrost, covered in summer with thermokarst "thaw lakes" of melted ice. Ice features such as ice wedges and pingo mounds of soil and ice can be found. This coast has an arctic climate warm enough to allow plant growth in late-June, July and August only, and even then frosts may occur.
There are no trees in the Baffin Mountains because they are north of the Arctic tree line. Rocks that compose the Baffin Mountains are primarily deeply dissected granitic rocks. They were covered with ice until about 1500 years ago, and vast parts of them are still ice-covered.