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The Arctic is an Ecosystem
by Bill Heal
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The Arctic Gradients
  The Arctic Ecosystem is a jigsaw. The picture is made up of many parts. The ecosystems that we normally recognise, the different habitats, are each systems that have interconnected parts and processes. But, as you have seen, they are not completely self-contained and isolated from each other. They also change gradually along distinct environmental gradients. It is these physical gradients which determine the structure and function of the ecosystems, their dynamics and their responses to the ever changing environment.
  What are these gradients? On land, in freshwaters and in the sea, a dominant gradient is the rise in temperature from North to South, but other large scale physical gradients have major effects on the structure and function of the ecosystems.
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Sunrise over Eyjafjord, Akureyri Iceland. The mountains shelter the valley from the wind. Photo: Jonas Allansson

On land, from the coast to inland areas, the oceanic-continental gradient in climate gives increasing seasonal range of temperature and decreasing rain and snowfall. Ranges of mountains, especially near the coast, intercept clouds and cause major local increase in rain and snowfall. The mountains also provide sharp local altitudinal gradients in temperature.

Freshwater systems are dominated by topography (slope and steepness), determined mainly by geology. The mountain glaciers and rivers flow sharply to the sea or spread over the vast continental areas of flat tundra.

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Marine systems grade from the shore, through the tidal zone, over theextensive,gently sloping continental shelf and down to the deeper ocean floor, with its submerged valleys, troughs and mountains - a mirror image of the land surface (see figure 7a and figure 7b).

How do these systems respond to the environmental gradients? How do the structures and processes change? How do the pieces of the jigsaw change? Examine the dynamics more closely as you move along the gradients of the three subsystems - the land (terrestrial), the freshwater (hydrological), and the marine.

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The Arctic is an Ecosystem, by Bill Heal.
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