About Field Sites
Great Smoky Mountains National Park, Twin Creeks (GRSM) is a terrestrial NEON site located in the mountains of southeastern Tennessee near the North Carolina border. It is comprised of 32.7 km2 (8080 acres) within the 2108 km2 (814 sq. mi.) Great Smoky Mountains National Park. GRSM is characterized by abundant rainfall, variable elevations, and an exceptional richness of biota hosted by closed-canopy deciduous old growth forests. As one of the largest protected areas in the eastern U.S., it is the most biodiverse park in the National Park system and the most visited. GRSM is part of NEON Domain 07 - Appalachians & Cumberland Plateau, which includes eastern Tennessee, most of Kentucky, southern Ohio, and parts of North Carolina, Georgia, Indiana, and Illinois. D07 includes four other NEON field sites, including two additional terrestrial sites and two aquatic sites. GRSM is colocated with the LECO aquatic field site.  
The park’s altitude variation simulates the climate and habitat changes you would experience traveling north or south across the eastern United States. The cool, moist environment found in higher elevations is juxtaposed against the drier, warmer lowlands. Temperature ranges are dependent on elevation and can vary 6-11°C (10-20°F) from mountain base to top. Average annual rainfall also varies with these elevation changes, ranging from approximately 1400 mm (55 in.) in the lower valleys to over 2160 mm (85 in.) on some of the highest peaks. Mean annual temperature is 13.1°C (56°F) and mean annual precipitation is 1375 mm (55 in.). With the exception of the Pacific Northwest, the Great Smoky Mountain Park receives more annual rainfall than anywhere else in the contiguous United States. This heavy rainfall can cause extreme weather events such as flash flooding, particularly in the spring and summer months. During fall and winter, winds can become strong and damaging, reaching up to 80-100 mph as a result of a phenomenon known as mountain waves.     
The Great Smoky Mountains belong to the Snowbird Group, a geologic unit consisting of siltstone and sandstone. 
Climatic variations throughout the Great Smoky Mountains Park contribute to its diverse soil composition and chemistry. Soil parent materials consist of residuum, colluvium, and local alluvium weathered or derived from Precambrian-, Late Proterozoic- and Paleozoic-age crystalline (igneous and metasedimentary) and sedimentary rocks. Organic Horizon thickness ranges from 2-7 cm (0.75 - 2.75 in.) and notably, many fine, medium, and coarse roots were found in the surface horizons. Dominant soil series at this site are from the Spivey-Santeetlah-Nowhere complex.   
Light rainfall is the dominant form of precipitation at GRSM, governing the region's water cycle by accounting for 50-60% of a year’s total. Because it falls slowly and continuously, water efficiently infiltrates soil layers, percolating deep and recharging underground aquifers. 
Variations in elevation, rainfall, temperature, and geology in GRSM provide habitat for over 1600 species of flowering plants. In addition, the park is one of the largest stands of deciduous old growth forest in North America. The lower region forests are dominated by deciduous leafy trees including yellow poplar (Liriodendron tulipifera), red maple (Acer rubrum), and chestnut oak (Quercus montana). Spice bush (Lindera benzoin), mountain laurel (Kalmia latifolia), and rhododendron (Rhododendron maximum) dominate the dense understory. At higher altitudes, deciduous forests give way to coniferous trees like Fraser Fir (Abies fraseri), red cedar (Juniperus virginiana), and eastern hemlock (Tsuga canadensis). Of these species, 76 plants are listed as threatened or endangered in the states of Tennessee and North Carolina. Spreading avens (Geum radiatum), Virginia spiraea (Spiraea virginiana), and rock gnome lichen (Gymnoderma lineare) are federally listed threatened and endangered species that can be found in the park. 
Animals of the Great Smoky Mountains National Park have been thoroughly documented since an inventory of all taxa began in 1998. Fauna present in the Great Smoky Mountains are representative of species found in both the northern and southern regions of the United States. Northern species have found suitable ecological niches in the park’s mountainous areas, allowing them to live far south of their present primary ranges, while southern species are found in the warmer lower valleys. Of the 66 mammal species that are recognized to inhabit the park, white-tailed deer (Odocoileus virginianus), black bear (Ursus americanus), groundhog, squirrel, and bat species are the most frequently seen. Notably, the park hosts high concentrations of black bears, 30 salamander species and a number of endangered species such as the northern flying squirrel (Glaucomys sabrinus), Red-cockaded Woodpecker (Leuconopticus borealis), Indiana bat (Myotis sodalis), spruce-fir moss spider (Microhexura montivaga), and the Smoky madtom (Noturus baileyi). NEON samples for and provides data on five types of wildlife: small mammals, birds, mosquitoes, ticks, and ground beetles. 
Past Land Management and Use
Designated as a National Park by the U.S. Congress in 1934, the Great Smoky Mountains National Park was officially dedicated by President Franklin D. Roosevelt in 1940. This designation was historically significant as it was the first national park paid for in part by the federal government. GRSM encompasses a rich mosaic of historical use including human influence from prehistoric Paleo Indians, 1880s European settlement and 20th century loggers. Prior to its establishment as a national park, many historic species were eradicated from the ecological framework including bison, elk, mountain lion, gray wolf, red wolf, river otter, and several species of fish. The extraordinary biodiversity exhibited in the park’s 2108 km2 (814 sq. mi.) of plant-covered, gently-contoured mountains led to its designation as one of the first UNESCO World Heritage Sites in 1983. The North American deciduous old growth forest was plagued by wildfires in late 2016, burning more than 10,000 acres of the park, including areas in the NEON sites.    
Current Land Management and Use
The Great Smoky National Park is considered the most biodiverse and most visited national park in the United States. Management decisions are informed by available scientific data. The park encourages scientists and students from a multitude of institutions and organizations to contribute to current research, which is ultimately accessible to the public. In 1998, scientists began documenting all life forms found in the park, commonly referred to as an All Taxa Biodiversity Inventory. Since its inception, the project has documented over 19,000 species, with 1000 species that have never been seen anywhere else in the world. The park has over 100 active research permits currently issued, with scopes of study including fire impacts, water quality, fish, soils, geology, plants, mammals, birds, invertebrates, fungi, bacteria, precipitation, and pollution. In addition to the environmental data collection and research that the park hosts, the National Park Service has helped to reintroduce previously extirpated species including the river otter, elk, and peregrine falcon.  
NEON Site Establishment
The NEON program site within the Great Smoky Mountains was established in November 2015. The Airborne Observation Platform (AOP) was flown over both sites collecting lidar data and hyperspectral and high-resolution RGB ortho-photos of the surrounding vegetation and landscape. Observational sampling also began in 2015. Two full seasons of organismal and biogeochemical data were collected before a significant wildfire in 2016. This site encompasses a sampling area of 32.72 km2, including distributed base plots and tower plots. TOS Distributed Plots were allocated at this site according to a spatially balanced and stratified-random design based on data from the 2006 National Land Cover Database, chosen for its consistent and comparable data availability across the United States. TOS Tower Plots were allocated according to a spatially balanced design in and around the NEON tower airshed.  
 Terrestrial Observation System (TOS) Site Characterization Report: Domain 07. NEON.DOC.003891vB
 U.S. Geological Survey, 2005, Mineral Resources Data System: U.S. Geological Survey, Reston, Virginia. https://mrdata.usgs.gov/mrds/
 PRISM Climate Group., Oregon State University, http://prism.oregonstate.edu, created 4 Feb 2004.
 NOAA. 2000. A Precipitation and Flook Climatology with Synoptic Features of Heavy Rainfall Across the Southern Appalachian Mountains. http://nwafiles.nwas.org/digest/papers/2000/Vol24No3/Pg3-Gaffin.pdf
 Smith, Tiffany. (2018). NEON Site-Level Plot Summary, Great Smoky Mountains National Park (GRSM), October 2018. https://data.neonscience.org/documents/10179/2361410/GRSM_Soil_SiteSumm…
 Soil Survey of Great Smoky Mountains National Park, Tennessee and North Carolina https://www.nrcs.usda.gov/Internet/FSE_MANUSCRIPTS/tennessee/TN640/0/GS…
Remote sensing surveys of this field site collect lidar, spectrometer and high-resolution RGB camera data.
This site has a flux/meteorological tower that is 45 m (148 ft) tall with six measurement levels. The tower top extends above the vegetation canopy to allow sensors mounted at the top and along the tower to capture the full profile of atmospheric conditions from the top of the vegetation canopy to the ground. The tower collects physical and chemical properties of atmosphere-related processes, such as humidity, wind, and net ecosystem gas exchange. Precipitation data are collected by a tipping bucket at the top of the tower and a series of throughfalls located in the soil array.
Soil Sensor Measurements
This site has five soil plots placed in an array within the airshed of the flux tower. Photosynthetically Active Radiation (PAR) at soil surface, soil heat flux, solar radiation, and throughfall are measured at the soil surface in each soil plot. Soil moisture, soil temperature, and CO2 concentration are measured at multiple depths in each soil plot.
At terrestrial sites, field ecologists observe birds and plants, and sample ground beetles, mosquitoes, small mammals, soil microbes, and ticks. Lab analyses are carried out to provide further data on DNA sequences, pathogens, soils, sediments, and biogeochemistry. Learn more about terrestrial observations or explore this site's data products.
Field Site Data
National Park Service
Site Access Allowed
Site Access Details
The National Park Service is open to additional research activities taking place in this area. Apply via IRMA Permitting portal.
NEON Field Operations Office
NEON Field Operations Address
154 Fairbanks Road, Fairbanks Plaza
Oak Ridge, TN 37830
NEON Field Operations Phone
Mean Annual Temperature
Mean Annual Precipitation
Dominant Wind Direction
Mean Canopy Height
Dominant NLCD Classes
Deciduous Forest, Evergreen Forest
Average number of green days
Average first greenness increase date
Average peak green date
Average first greenness decrease date
Average minimum greenness date
Number of Tower Levels
USGS Geology Unit
USGS Geology Name
Snowbird Group, including Pigeon Siltstone, Roaring Fork Sandstone, Metcalf Phyllite, Longarm Quartzite, and Wading Branch Formation
USGS Lithologic Constituents
Siltstone with sandstone
USGS Geology Age
Megapit Soil Family
Loamy, skeletal, isotic, mesic. Typic Humudepts.
Other Domain D07 Field Sites
Other Field Sites in TN