Arctic LTER

Sampling at Arctic LTER

Key Research Findings:

Continuous addition of the tracer 15N (nitrogen isotope) to streams is a method for measuring nitrogen cycling in flowing waters was pioneered by ARC scientists. This technique has transformed the study of streams and is now used throughout the world.
Long-term experimental additions of small amounts of phosphorus to arctic streams contributed to what is now a general principle of stream ecology: nutrient addition stimulates increased algal and plant growth, which leads to a cascade of impacts on food webs, community structure, and biodiversity.
ARC scientists have determined that fish in arctic lakes depend on benthic (bottom-dwelling) plants and algae for food since phytoplankton growth is so low in most of these ecosystems. This finding was revealed through a combination of long-term observations, lake fertilization experiments, and new 15N (nitrogen isotope) tracer methods that measure nitrogen cycling.


The Arctic LTER research site is in the foothills region of the North Slope of Alaska 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 is the dominant vegetation type but there are extensive areas of drier heath tundra on ridge tops and other well-drained sites as well as areas of river-bottom willow communities. The North Slope is divided into the Coastal Plain (6,000 km²), the Foothills (95,000 km²), and the Mountains (40,000 km²).

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The key event in the development of research in the Upper Kuparuk/Toolik Lake region was the construction of the Alaska oil pipeline and Haul Road (later named the Dalton Highway) in 1974- 1976 (Alexander and VanCleve, 1983). Before that time, access to interior regions of the North Slope was limited by the lack of roads and the small number of widely scattered locations where aircraft (mostly fixed-wing) could land, take off, and be fueled or serviced. Completion of the Haul Road in September 1974 suddenly opened up a magnificent environmental transect across the heart of northern Alaska. Toolik Lake and the Upper Kuparuk River lie near the center of this transect, and ecologists and other environmental scientists were quick to exploit the opportunities for new research in the surrounding area.

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Research Topics:

Movement of nutrients from land to stream to lake; changes due to anthropogenic influences; controls of ecological processes by nutrients and by predation.

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