About Field Sites
The Santa Rita Experimental Range (SRER) site is a terrestrial NEON field site located on the the Santa Rita Experimental Range and Wildlife Area, the oldest continuously utilized long-term agricultural research station in the U.S. Located 35 km (21.8 mi.) outside of Tucson, Arizona, the 214.9 km2 (53,101 acre) data collection site is hosted by the University of Arizona. Data collected here help scientists understand the functions of desert ecosystems; deserts are uniquely sensitive to human disturbances. SRER is located in NEON's Desert Southwest Domain (D14). D14 has one other terrestrial field site and one aquatic field site. SRER is not colocated with an aquatic site.   
The Santa Rita Experimental Range, located in the massive Sonoran Desert, is characterized by a semi-arid, hot climate. Winters are short and mild, while summers are long and hot. The mean annual temperature is 19.3°C (67°F). The Sonoran Desert is wetter than most deserts, and SRER has a mean annual precipitation of 346.2 mm (13.6 in.) each year. Precipitation has a bimodal distribution in this region, with gentle, quenching rains in the winter and fierce thunderstorms during the summer monsoons. However, there are many months between the wet seasons, so both plants and animals in the area are adapted to arid conditions. The lack of prolonged freezing temperatures in winter means that columnar cacti and other large succulents are common. During any season, diurnal temperature swings of up to 15°C (59°F) are common.   
The SRER is located at the foothills of the Santa Rita Mountains. The range itself consists of some isolated foothills but is mostly comprised of gently sloped alluvial fans cut by canyons and arroyos. The geology of SRER is characterized by undivided sand and gravels.  
The soils found at SRER are those typical of desert regions - they are mostly composed of alluvial deposits from the Santa Rita Mountains, with alluvial caps covering approximately 95% of the region. The soil subgroup Typic Torrifluvents, within Entisols, are commonly found in NEON plots at SRER. Higher-elevation soils have higher organic content, less salt, and lower temperature than soils at lower elevations. 
Arroyos and gullies are common within the experimental range, representing the alluvial fan dominated area. Runoff flows to the west and northwest into the Santa Cruz River. 
The dominant vegetation found in an area is highly dependent on elevation. For example, densities of velvet mesquite (Prosopis velutina) and cholla cactus (Cylindropuntia spp.) are greatest at elevations between 975 - 1100 m (3200 - 3600 ft.), but creosote bush (Larrea tridentata) dominates at elevations lower than 975 m (3200 ft.). Vegetation at the site is dominated by drought-resistant, thorny species. This includes a mix of short trees, shrubs, cacti and other succulents, perennial grasses, and annual forbs.  
There are many distinctive faunae found in the Santa Rita Experimental Range. One of the most interesting mammals in the region is the carnivorous grasshopper mouse (Onychomys torridus). These mice eat everything from large insects to other mice and even scorpions. Grasshopper mice have evolved to not feel the pain of bark scorpion venom, so even if they get stung by their prey, they don’t feel the lasting, burning pain most vertebrates associate with scorpion stings. This allows the mouse to take advantage of an otherwise inaccessible food source and survive in the harsh desert environment. 
Past Land Management and Use
Established in 1903 by the U.S. Forest Service, the Santa Rita Experimental Range was managed by USDA until around 1988 when control was handed over to the University of Arizona. Establishment of the SRER to study rangelands over time was prompted by several severe droughts at the end of the 1800s that completely wiped out some ranchers in the region and exposed the delicate nature of arid rangelands. When research on SRER first started, the land was badly degraded by the grazing of unregulated cattle. Subsequently, the area was fenced off and grazing prohibited until 1915. This gave scientists time to study forage plants on the range, including their phenology and carry capacity for grazing, and how to restore the denuded landscape for future grazing. Over time, the focus of research at SRER has shifted from rangeland and cattle management to more general studies about ecology, climate change, and environmental restoration.   
Current Land Management and Use
Control of the experimental range changed hands in 1988 and is now hosted by the University of Arizona. Both the College of Agriculture and Life Sciences and the School of Natural Resources at the University of Arizona use this site as an outdoor laboratory to test pressing questions about ecology, climate change, range management, and wildfire. The mission of the School of Natural resources at the SRER is "To advance research and education on the ecology and management of desert rangelands through the secure, long-term access to research areas, state-of-the-art facilities, new discoveries, and research legacies." The SRER is considered a world-class facility because since its inception over 100 years ago scientists have kept meticulous records of their research, resulting in a huge repository of information about arid grasslands and how to manage them.   
NEON Site Establishment
Plots for SRER were established in January 2015, and terrestrial sampling began in early 2016. The final instrumentation suite was installed in April 2017.
 U of A description of the range: https://cals.arizona.edu/srer/history/contents.html
 Terrestrial Observation System (TOS) Site Characterization Report: Domain 14. NEON.DOC.003897vA
 SNRE Archive: https://archive.is/20131210210738/http://www.snr.arizona.edu/project/sr…
 Sayre, N. F. (2003). Recognizing History in Range Ecology: 100 Years of Science and Management on the Santa Rita Experimental Range. USDA Forest Service Proceedings.
 U of A SNRE site: https://snre.arizona.edu/facilities/srer
 U.S. Geological Survey, 2005, Mineral Resources Data System: U.S. Geological Survey, Reston, Virginia. https://mrdata.usgs.gov/mrds/
 Rowe AH, Xiao Y, Rowe MP, Cummins TR, Zakon HH. Voltage-gated sodium channel in grasshopper mice defends against bark scorpion toxin. Science. 2013;342(6157):441‐446. doi:10.1126/science.1236451
 The North American Monsoon. (2004). Reports to the Nation.
 Sonoran Desert Museum: https://www.desertmuseum.org/kids/oz/long-fact-sheets/Saguaro%20Cactus…
 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 8 m (26 ft) tall with four 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
University of Arizona
Site Access Allowed
Site Access Details
SRER encourages research activities that do not conflict with on-going research. Researchers should apply directly for a site research permit. All proposed actions will be reviewed for potential impacts to cultural resources, endangered species and other research activities.
NEON Field Operations Office
NEON Field Operations Address
2115 East Valencia Rd, Suite 131
Tucson, AZ 85706
NEON Field Operations Phone
Mean Annual Temperature
Mean Annual Precipitation
Dominant Wind Direction
Mean Canopy Height
Dominant NLCD Classes
Average number of green days
Average first greenness increase date
Average peak green date
Average first greenness decrease date
Average minimum greenness date
219; 334 DOY
Number of Tower Levels
USGS Geology Unit
USGS Geology Name
Quaternary surficial deposits, undivided
USGS Lithologic Constituents
Silt, clay, and sand
USGS Geology Age
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