About Field Sites
The San Joaquin Experimental range (SJER) is a terrestrial NEON field site located approximately 40 km (25 mi.) north of Fresno, CA. The 18.2 km2 (4500 acre) site sits at 210-520 m (690-1700 ft.) above sea level in the foothills of the Sierra Nevada mountains and is hosted by the U.S. Forest Service. The area is mainly grassy open oak woodland and drains into the San Joaquin River basin. It is part of the Pacific Southwest Domain (D17), which is bounded by the Pacific Ocean on the west and the Sierra Nevada Mountains on the east, and encompasses most of California. There are four other NEON field sites in D17, including two additional terrestrial sites and two aquatic sites. 
SJER has a Mediterranean climate. Winters are cool and wet; the rainy growing season typically runs from October to April, with peak greenness in early March. Summers are hot and dry, with average temperatures between 24-27°C (75-80°F), and high temperatures frequently exceeding 38°C (100°F). Vegetation is mostly dormant during the summer months. Mean annual temperature is 16.4°C (61.5°F). Mean annual precipitation is 539.62 mm (21.25 in.).  
The geology of SJER is granodiorite and quartz monzonite. 
At SJER parent materials consist of residuum, colluvium, and local alluvium that are derived from Mesozoic aged granite, quartz monzonite, granodiorite, and quartz diorite crystalline rocks. The primary soil series on the site are Ahwahnee (Coarse-loamy, mixed, active, thermic Mollic Haploxeralfs) and Vista (Coarse-loamy, mixed, superactive, thermic Typic Haploxerepts). Both soils are moderately deep to a paralithic contact. 
SJER is primarily open oak woodland, with an overstory of evergreen oaks, gray pine, scattered manzanita and whitethorn shrubs. The understory is cool season grasses (predominantly Bromus) with other perennial forbes and legumes. Native bunch grasses can be found on some northern slopes.  
A large population of California ground squirrels (Spermophilus beecheyi) and other small rodents supports abundant mesocarnivores, including coyotes (Canis latrans), American badgers (Taxidea taxus), and bobcats (Lynx rufus), as well as gopher snakes and rattlesnakes. The site hosts a wide variety of resident and migratory songbird and raptor species, including the important game species California quail (Callipepla californica). Species unique to the region include the Western spadefoot toad (Spea hammondii), San Joaquin pocket mouse (Perognathus inoratus), and Heerman's kangaroo rat (Dipodomys heermani). 
Past Land Management and Use
The San Joaquin Experimental range was established in 1934 as California's first range research station. Its original research goal was to identify cost-effective methods of livestock production and monitor its effect on the annual grass and oak woodland ecosystem. Research objectives have since expanded to contribute to scientific knowledge of ecological patterns and processes in this ecosystem. In 2009, the Southern Sierra Critical Zone Observatory established an eddy-covariance flux tower on the site to monitor meteorological processes along the critical zone elevation gradient.
The period between 2011 and 2015 marked the driest years on record in California, and significantly reduced the flow of the San Joaquin river. Multiple small wildfires have affected the site and its surroundings in recent years.     
Current Land Management and Use
SJER is currently managed in collaboration by the Pacific Southwest Research station of the United States Forest Service and California State University at Fresno's Agricultural foundation. It hosts the university's commercial cow-calf herd. The range serves as an outdoor lab for agriculture students at Fresno State and Fresno City College and is used for extensive ecological and agricultural research. Data collected at San Joaquin forms the basis for over 500 scientific publications in disciplines ranging from livestock production to nutrient flow modeling and fire ecology.
The area immediately surrounding SJER is agricultural, primarily cattle pasture with some wine and fruit production. The site is situated relatively close to two urban areas: the city of Fresno, 32 km (20 mi.) south, and Coarsegold/Oakhurst, 24 km (15 mi.) north. 
NEON Site Establishment
NEON plot establishment at SJER began in 2015, and was completed in 2016. The site transitioned to operations in October 2016. The terrestrial sampling and observations began in the same month, coinciding with the start of the central valley’s cool, rainy growing season. Construction of the site’s 39 m (127 ft.), 6-level instrumentation tower was completed in 2017, and the tower came online and began streaming data in the fall of 2018.
 Terrestrial Observation System (TOS) Site Characterization Report: Domain 17. NEON.DOC.003900vB
 Larson, J. H., J. Stebbins, and W. L. Porter. 1985. A revised checklist of plants of the San Joaquin Experimental Range. California State University, Fresno. California Agricultural Technology Institute, CATI Publication 850303. 38 p.
 Kunch, Theresa. (2018). NEON Site Level Plot Summary, San Joaquin Experimental Range (SJER), April 2018. https://data.neonscience.org/documents/10179/2361410/SJER_Soil_SiteSumm….
 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.
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 39 m (128 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 Double Fence Intercomparison Reference (DFIR) near 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
US Forest Service
Site Access Allowed
Site Access Details
Researchers should coordinate directly with the US Forest Service for permitting and approval.
NEON Field Operations Office
NEON Field Operations Address
4727 West Shaw Avenue
Fresno, CA 93722
NEON Field Operations Phone
Mean Annual Temperature
Mean Annual Precipitation
Dominant Wind Direction
Mean Canopy Height
Dominant NLCD Classes
Evergreen Forest, Grassland/Herbaceous, Shrub/Scrub
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
Mesozoic granitic rocks, unit 3 (Sierra Nevada, Death Valley area, Northern Mojave Desert and Transverse Ranges)
USGS Lithologic Constituents
Primarily granodiorite, tonalite, quartz monzonite, and granite
USGS Geology Age
Permian to Tertiary; most Mesozoic
Other Domain D17 Field Sites
Other Field Sites in CA