Researchers started a research site at Toolik Lake in Alaska in 1975 to study arctic lake and streams. Some researchers who would later become part of the Ecosystems Center studied ecosystems at the far-north location of Barrow, Alaska, as part of the International Biological Program from 1971 to 1973. After the IBP ended, some researchers set out to find a new arctic research site, and they chose Toolik Lake, Alaska. Toolik Lake is located in northeast Alaska, in the northern foothills of the Brooks Range of mountains. The US National Science Foundation (NSF) and Department of Energy funded some of the initial ecological studies at Toolik Lake. The arctic ecosystem at Toolik Lake was ideal for terrestrial and aquatic ecological research because while most of the year it was frozen over, it was active during three months in the summer, so researchers could concentrate their studies in a short time period.
Ecosystems Center scientists John Hobbie, Bruce Peterson, and Gus Shaver were involved in the first experiments at Toolik Lake, along with their collaborator, F. Stuart “Terry” Chapin III from the University of Alaska. Scientists from the Ecosystems Center started studying bacteria that lived in the lake and how nutrients in the soil affected plant growth. Hobbie and Peterson began a study on nutrient fertilization starting in 1983 to test how an increase in nutrients might impact organisms in lakes and streams. The researchers added phosphorus and nitrogen fertilizers to large, floating corrals in Toolik Lake. They also added phosphorus directly to Kuparuk River, a river near Toolik Lake, and in small tube chambers in the river. Researchers then tracked the changes in the ecosystem—usually seen in the growth of microbes and algae. During the first eight years of the stream fertilization experiment, insect populations increased. But in the second eight years, a moss took over the river bottom, which affected all other biotic communities in the stream.
In 1987, the NSF awarded researchers from the Ecosystems Center a grant to make Toolik Lake a Long Term Ecological Research (LTER) site focused on arctic tundra ecosystems. John Hobbie, Brian Fry, Anne Giblin, Knute Nadelhoffer, Bruce Peterson, Ed Rastetter, and Gus Shaver were all involved in the first LTER project at Toolik Lake. The researchers decided that the Arctic LTER should aim to link studies of terrestrial and aquatic ecosystems using new experimental techniques such as stable isotope tracer studies. One of the first projects was to collect baseline data, such as nutrient concentrations, pH levels, insect populations, plant species, and weather data. By 1998 researchers made over 1,000 datasets from the Arctic LTER available online.
Researchers decided by 1998 to focus new studies at the Arctic LTER on understanding the effects of global change on arctic ecosystems, and to predict long-term environmental change. Records showed that in the 30 years up to 1998, the temperature of the region had risen by 0.5 degrees Celsius per decade. Researchers wanted to know the impact of predicted temperature change on the region. In one of the long-term experiments at the Toolik Lake site, which started in 1981, researchers studied the impact of increased the temperature and nutrient level of several small plots of land. They used greenhouses to increase the temperature and fertilizer to increase the nutrient levels. Researchers then measured how these experimental variables changed plant and microbial growth and feedbacks, which could help predict how ecosystems might respond to a warmer climate. In recent years, the Arctic LTER has focused on the direct and indirect impacts of climate change on the north Alaskan ecosystem.