Toolik Lake Research Natural Area (TOOL) is a terrestrial NEON field site near Toolik Field Station, AK, just north of the Brooks Range. The 60 km2 (14,800 acre) site is located 254.3 km (158 mi.) above the Arctic Circle and 188 km (116 mi.) from the Arctic Ocean. TOOL’s field sampling area is managed by the Bureau of Land Management as a Resource Natural Area and Area of Critical Environmental Concern, but housing and logistics are supported by Toolik Field Station (TFS). TFS is operated by the Institute of Arctic Biology at the University of Alaska Fairbanks, with cooperative agreement support from the Division of Polar Programs, Directorate for Geosciences at the National Science Foundation. TOOL sits at 700 - 985 m (2300 - 3200 ft.) above sea-level, which demarcates taiga and tundra ecosystems in Alaska. It provides a contrast to BARR, which is on the northern coastal floodplains. In both cases, field site boundaries overlap other ecological research networks, allowing opportunities for larger datasets and longer time series. TOOL is part of the NEON Tundra Domain (D18), which includes the northern and western parts of Alaska. D18 hosts three other NEON field sites in Alaska: two aquatic sites and the BARR terrestrial site. TOOL is colocated with the two D18 aquatic sites, Toolik Lake (TOOK) and Oksrukuyik Creek (OKSR).