Oak Ridge National Laboratory (ORNL) is located at the U.S. Department of Energy's Oak Ridge Reservation in Roane County, Tennessee. The ORNL reservation is situated within the borders of five parallel ridges and valleys to the north of the Clinch River that are part of the Ridge-and-Valley Appalachians physiographic province (Environmental Sciences Division n.d.). The NEON tower site and Walker Branch aquatic site at ORNL are located within the Walker Branch Watershed, a 100 ha area that has served as the site for long-term environmental studies by the Environmental Sciences Division at ORNL, NOAA, and many visiting university researchers.
The ORNL climate is typical of the humid southern Appalachian region: mean annual precipitation in the Walker Branch Watershed is 151 cm and mean temperature is 14.5 ⁰C.
Vegetation within ORNL is primarily a mixture of oak (Quercus spp.) and hickory (Carya spp.), with patches of shortleaf pine (Pinus echineta) and Virginia pine (Pinus virginiana) on the ridges and mesophytic hardwoods in the valleys. The Walker Branch watershed is a dominated by second-growth deciduous forest of chestnut oak (Quercus prinus), tulip poplar (Liriodendron tulipifera), red maple (Acer rubrum), white oak (Quercus alba), and American beech (Fagus granifolia) (Johnson and Van Hook 1989). Canopy height is ~28 m near the tower site with lowest branches at ~10 m above ground level. Seedlings and saplings form and understory 5-10 m in height.
Outside of the NEON site boundaries, the U.S. Department of Energy's research facility includes the Y-12 National Security Complex, used for nuclear weapons processing and materials storage. This area, in addition to the East Tennessee Technology Park (ETTP), is considered a sensitive area with national security concerns.