About Field Sites
Lajas Experimental Station (LAJA) is a terrestrial NEON field site located in the southwestern corner of Puerto Rico in the Lajas Valley. The site consists of two areas, a plot of farmland owned by a private farmer known as Hacienda Resolucion and the Lajas Experimental Station, one of six Agricultural Experimental Stations on the island. Hacienda Resolucion is east of the dairy farm managed by the Experimental Station and west of the Laguna Cartagena National Wildlife Refuge managed by the Fish and Wildlife Service. The Lajas Experimental Station is managed by the University of Puerto Rico – Mayaguez Campus. NEON samples approximately 3.9 km2 (976 acres) of land at the station. This location is part of the NEON Atlantic Neotropical Domain (D04), which includes the island of Puerto Rico and the southern tip of Florida. The Domain includes one additional terrestrial field site and two aquatic field sites.   
The local climate in Lajas, Puerto Rico is dry, which is typical for the region. The LAJA site receives about 830 mm (32.7 in.) of rainfall per year and most of this occurs in the months of September, October and November. The site’s annual average temperature is 25°C (77°F). Factors such as constant wind, high temperatures and low relative humidity cause a high degree of evaporation in the area, especially in the summer, when temperatures can reach 91°C. The site can be subject to hurricanes, which are an important feature of the climate of the Atlantic Neotropical Domain.  
The Lajas Agricultural Site is composed of alluvium, a sediment composed of materials such as clay, silt, sand, or gravel, deposited during recent geological time by a stream or other body of running water.  
Soils within the site are from the order Vertisol, which are clay-rich soils that typically form under grassland vegetation. These types of soils are best suited for use as pastureland and for cultivation. Subgroup classification is Sodic Haplusterts.   
The Lajas Valley is about 13 m (43 ft.) above sea level. Hydrology characteristics of the area surrounding the Lajas Valley consist of a drainage that runs alongside PR Route 303 that divides the eastern and western sides of the valley. Alluvial deposits are the primary aquifer in the area. These deposits are formed of consolidated sedimentary rocks and the aquifer is recharged by rainfall. Groundwater discharge occurs by means of evapotranspiration and pumping. 
Crop types are rotated depending on current research priorities in the Lajas Experimental Station. Dominant vegetation in the privately owned farmland that makes up the other part of the LAJA site consists mostly of crops cultivated for livestock feeding.  
The LAJA site is home to various endangered species like the Puerto Rican nightjar (Caprimulgus noctitherus), yellow-shouldered blackbird (Agelaius xanthomus), and Puerto Rican boa (Epicrates inornatus). Fauna at the station consists mostly of livestock animals such as dairy cattle used in genetics research, quail, and rabbits, among others. Insects include grasshoppers; beetles such as Apenes portoricensis; ants; and mosquitoes such as Aedes aegypti, Culex erraticus, Mansonia dyari, and Uranotaenia sapphirina. NEON provides data on five types of wildlife: small mammals, birds, mosquitoes, ticks, and ground beetles.   
Past Land Management and Use
The Lajas Agricultural Experimental Station was established in 1946 as the Lajas Research and Development Center. The goal of this center was to be able to conduct research that would aid the development of agriculture in the southwest area of Puerto Rico. 
Current Land Management and Use
The Lajas Agricultural Experimental Station was founded in 1946 with the purpose of conducting the research necessary to develop agriculture in the southwest area of Puerto Rico. In this Experimental Station, fundamental research is carried out aimed at developing and increasing the production efficiency of new and traditional crops. In addition, this is the local office of the Agricultural Extension Service and the UPRM Animal Science Department, serves as the headquarters of the Aquaculture Program of the Department of Marine Sciences, and collaborates with United States universities in studies of plant breeding of rice and soybeans. The station has cooperative agreements with external institutions such as the Mayagüez Tropical Agriculture Research Center; the Universities of Louisiana, Texas A&M, Arkansas, and Florida; the National Weather Service; and the Department of Agriculture of Puerto Rico, among others.   
NEON Site Establishment
NEON plot establishment at LAJA began in 2016 and was completed in that same year. The site transitioned to operations in September 2016. The terrestrial sampling and observations began in June 2016. Construction of the site’s 8 m (26 ft.), 4-level instrument tower was completed in 2015, and the tower came online and began streaming data in the summer of 2016. 
 Terrestrial Observation System (TOS) Site Characterization Report: Domain 04. NEON.DOC.003888vB
 2016. Designación de la Reserva Agrícola de la Estación Experimental Agrícola del Recinto Universitario de Mayagüez de la Universidad de Puerto Rico
 Location of La Hacienda Resolucion and Usage (Domain Manager and Domain Botanist, personal communication, May, 2020)
 SanClements, M., Lee, R.H., Ayres, E.D., Goodman, K., Jones, M., Durden, D., Thibault, K., Zulueta, R., Roberti, J., Lunch, C., & Gallo, A. (2020) Collaborating with NEON, BioScience 70 (2), 107-107, https://doi.org/10.1093/biosci/biaa005
 Bawiec, W.J., ed. (1999), Geology, geochemistry, geophysics, mineral occurrences and mineral resource assessment for the Commonwealth of Puerto Rico: U.S. Geological Survey Open-File Report 98-038, available online only at https://pubs.usgs.gov/pp/0953/report.pdf.
 Sercc.com. 2020. Home Page | Southeast Regional Climate Center. [online] Available at:
 USFWS Caribbean Ecological Services Field Office. (2020). List of threatened and endangered species.
 Weaver P. and Schwagerl J. (2009). U.S. Fish and Wildlife Service Refuges And Other Nearby Reserves In Southwestern Puerto Rico. International Institute of Tropical Forestry General Technical Report IITF-40. Available at https://www.fs.fed.us/global/iitf/pubs/GTR_IITF40.pdf
 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 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 tipping bucket at the top of the tower.
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, and solar radiation 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 Puerto Rico
Site Access Allowed
Site Access Details
The site host actively encourages research at this site, however all requests will be evaluated on a case-by-case basis. Please note that due to the high density of research taking place in this area, it is critical to coordinate closely with the site host to ensure no conflicts with ongoing research.; > 6months prior to planned schedule.
NEON Field Operations Office
Domain 04 Support Facility
NEON Field Operations Address
45 Carr Ochoa
Guanica, Puerto Rico 00653
NEON Field Operations Phone
Mean Annual Temperature
Mean Annual Precipitation
Dominant Wind Direction
Mean Canopy Height
Dominant NLCD Classes
Cultivated Crops, Grassland/Herbaceous, Pasture/Hay
Average number of green days
Number of Tower Levels
USGS Geology Unit
USGS Geology Name
USGS Lithologic Constituents
Unconsolidated clay, silt, sand and gravel
USGS Geology Age
Megapit Soil Family
Fine, mixed, superactive, isohyperthermic. Sodic Haplusterts.
Related Field Sites
Other Domain D04 Field Sites
Other Field Sites in PR