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Arctic LTER Site Description: Overview.

 


brooks with snow.JPG (19495 bytes)

 

The Arctic LTER research site (68°N and 149°W) is in the foothills region of the North Slope of Alaska (Fig. 1) and includes the entire Toolik Lake watershed and the adjacent watershed of the upper Kuparuk River, down to the confluence of these two watersheds. This area is typical of the northern foothills of the Brooks Range, with continuous permafrost, no trees, a complete snow cover for 7 to 9 months, winter ice cover on lakes, streams, and ocean, and cessation of river flow during the winter. Tussock tundra vegetation of sedges and grasses mixed with dwarf birch and low willows form the dominant vegetation type with areas of drier heath tundra on ridge tops and other well-drained sites as well as areas of river-bottom willow communities.

 

The climate at the site is typical of arctic regions, with a mean annual air temperature of about -10°C and low precipitation (45% of the 20-40 cm of precipitation falls as snow). During the summer the daily average air temperature is 7-12°C with the sun continuously above the horizon from mid-May to late July (Fig. 2). The snow-free season can lasts from late May to mid-September, with below-freezing temperatures and snow showers possible at any time. The entire region is underlain by continuous permafrost (depth of ~200 m at Toolik), which exerts a major influence on the distribution, structure, and function of both terrestrial and aquatic ecosystems. Since only 28-46 cm of the soil surface thaws annually, plants have limited rooting depth and soils saturate quickly with runoff immediate and flashy.  The cold, wet soils also inhibit decomposition although respiration of soil microbes can continue down to –7.5°C.

There has been a pronounced warming over the past 30 years in arctic Alaska.  Chapman and Walsh (1993) state that this warming has been as much as 2° in the winter and 1° in the summer.  Over the same period, the plant communities in the acidic tussock tundra at Toolik show a shift towards dominance of woody plants, especially the dwarf birch (Betula nana). In contrast, pollen from the sediments of lakes near Toolik show the plant communities being stable for some 6,500 years and with a peak of birch pollen abundance before that time.  The last glacial advance that reached Toolik was around 10,000 years ago.

 

Additional information.


Detailed description of the different Arctic LTER research areas:

 



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