The Arctic LTER site is located in the northern foothills of the Brooks Range, Alaska, in tundra vegetation of sedges and grasses mixed with dwarf birch and low willows. The tundra, streams and lakes at the site have been undisturbed and unchanged for more than 5,000 years. This allows the analysis of relationships among plants and animals in this ecosystem which is unaffected by an ecological legacy of human use. In contrast to this ecological stability, the climate of northern Alaska has changed remarkablyover the past 30 years. The temperature of the region has increased by more than 0.5oC per decade. No one knows if this warming is a part of the 3-5 degree change predicted by GCM models but it is known that other areas of the Arctic have either not changed or have become colder. Based on several types of observations, there appears to be a biotic response to this regional warming. The goal of this LTER project is to predict the future ecological characteristics of the site. This prediction is based on knowledge of the controls of ecosystem structure and function as exerted by physical setting and geologic factors, climatic factors, biotic factors, and the changes in fluxes of water and materials from land to water. The long-term research is based on the following approaches: (1) Long-term monitoring and surveys of natural variation of ecosystem characteristics in space and time. This will include routine monitoring of variables, such as climate, tundra plant communities and productivity, thaw depth, stream flow, stream chemistry, lake temperatures, lake chemistry, lake productivity and the abundance of zooplankton and fish. (2) A north-south regional transect in cooperation with the Bonanza Creek LTER program. (3) Experimental manipulations of ecosystems which are maintained and measured for decades. These experiments include tundra warming, shading and fertilizing, the exclusion of large herbivores, fertilization of lakes and streams, and the addition and removal of predators. (4) Synthesis and modeling efforts. Overall, this research will add to our basic understanding of the response of ecosystems to human induced global environmental change. In addition, these analyses will contribute to theoretical questions in ecology, including issues related to disturbances, resource availability, top-down vs. bottom-up controls on communities, and ecosystem structure and function.
