About Field Sites
Río Yahuecas (GUIL) is an aquatic NEON field site located in the central-western mountainous area of Puerto Rico. This site was formerly named Río Guilarte. Río Yahuecas site is a 2nd order, wadeable stream with a watershed of 9.5 km2 (2350 acres), comprised of agricultural lands and subtropical moist/wet forest. The NEON sampling reach of Río Yahuecas is located in a montane area with steep slopes, though large boulders stabilize the channel within the municipality of Adjuntas. Access to sensors and sampling locations in the reach of Río Yahuecas are located within the surrounding land, which is an agricultural research station owned and operated by the University of Puerto Rico – Mayaguez Campus. 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 two terrestrial field sites and one additional aquatic field site.  
The average annual precipitation is 1168 mm (46 in.) and the average annual temperature is 25°C (77°F). Overall, the climate in Río Yahuecas is a tropical-humid climate with a neutral pH, high precipitation levels, short photoperiods, and mild temperatures. 
Río Yahuecas is part of the Anon Formation, which consists of interbedded andesite (volcanic) breccia, rhyodacite, sandstone, and siltstone.  
The river lithology is mainly of the Anon formation: interbedded andesite or volcanic breccia, rhyodacite, and sandstone or siltstone of the Upper Eocene. Río Yahuecas substrate consists of a heterogeneous mixture of cobble, pebble and sand and large boulders are a dominant feature of the stream’s substrate regime.  
Río Yahuecas's watershed is comprised of agricultural lands and subtropical moist/wet forest. The flow regime in Río Yahuecas is typical of Puerto Rican streams draining rainforest catchments; characteristic discharge exhibits a strong seasonal pattern with low flows during the mid- to late- dry season (December through March) and high base flow discharge during the annual wet period (May through November). Extreme high flow events may ensue because of tropical storms or hurricanes, which typically occur between June and December. This NEON site’s reach is located in a montane area with steep slopes, though large boulders stabilize the channel and several large, slow-moving pools. Aside from large boulders, Río Yahuecas substrate consists of a heterogeneous mixture of cobble, pebble, and sand. 
Riparian vegetation along Río Yahuecas consists of tall grasses, shrubs, citrus trees and, in some places, a very narrow (~50 m) band of trees. The canopy at this wadeable stream is relatively open and sensor locations may be accessed from the facility roads easily. Vegetation within the Experimental Station consists crops grown for research in the central mountainous area of the Island.  
There is a variety of aquatic fauna within Río Yahuecas which include fish, amphibians, reptiles and macroinvertebrates, among others. Within the NEON site, a new species of diatom (Adlafia neoniana) was recently described, and has now been identified by researchers at the CUPE site as well. Species of fish include Poecilia reticulata, Xiphophorus hellerii, Xiphophorus variatus, and Gambusia affinis. None of them are native to the region and their food sources are mainly insects. Within the site, there are three endangered species, the Puerto Rican boa (Epicrates inornatus) and two birds, the Puerto Rican parrot (Amazona vittata) and the Puerto Rican sharp-shinned hawk (Accipiter striatus venator).   
Past Land Management and Use
The Association of Sugar Producers established the Adjuntas Agricultural Station, where Río Yahuecas is located, in 1910. In 1914, it became part of the Commonwealth of Puerto Rico, and in 1933 was transferred to the University of Puerto Rico – Mayaguez Campus, which remains in management. The Adjuntas Agricultural Experimental Station was originally located on the Finca Llinas in Castañer and in 1963 was relocated to its present location.  
Current Land Management and Use
This experimental station has around 184 plots of land that are used to cultivate coffee, citrus, bananas, ornamentals, hydroponic vegetables, and exotic fruit. The station is used by the University’s Faculty of Agricultural Sciences and by graduate students to carry out their thesis research and is the only agricultural experimental station in the central-western mountainous area of Puerto Rico. The research carried out in this substation is focused mainly on areas related to planting, fertilization, harvesting, varieties, pest and disease control, machinery, and economic studies of the main crops in that area. It is also home to a collection of coffee and citrus germplasm unique in its class and in the Caribbean.  
NEON Site Establishment
Establishment of the site GUIL began in January 2015 alongside a site characterization survey performed by the AQU team. A dry run of selected protocols at that site began in June 2015 and the site transitioned to full operations in September 2016. The aquatic instrumentation system came online in May 2018. 
 NEON.DOC.001648vC - D04 AQUATIC INSTRUMENT SYSTEM (AIS)
 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
 2016. Designación de la Reserva Agrícola de la Estación Experimental Agrícola del Recinto Universitario de Mayagüez de la Universidad de Puerto Rico
 USFWS Caribbean Ecological Services Field Office. (2020). List of threatened and endangered species.
Ciugulea I.,Burroughs S., Defrancesco C., Spitale D., Charles D.F., Lange-Bertalot H., & Cantonati M. (2019). Adlafia neoniana (Naviculaceae), new diatom species from forest streams in Puerto Rico. Plant Ecology and Evolutions. 152(2). Pp.378-384.Jensen B.,Parker S.M. Harrison N.,Monahan D. and Viggiano M. 2018. Fish Community of Hurricanes Irma and Maria on Puerto Rico Stream. Researchgate.URL.
 2019. Estacion Experimental Adjuntas. Universidad de Puerto Rico. URL: https://www.uprm.edu/eea/subestaciones/adjuntas/
 Camacho Lopez Y.,Kolterman D.A., Velez-Gavilan J.,Chinea-Rivera J.D.Wessel-Beaver L.,Cafaro M.J. (2017). Ecological Studies of the Tree Fern Alsophila Amitae D.S.Conant (Cyatheaceae) in the Cloud Forest of Puerto Rico. Universidad de Puerto Rico.
 Estado Libre Asociado de Puerto Rico Departamento de Recursos Naturales y Ambientales. (2008). Bosques de Puerto Rico: Bosque Estatal de Guilarte. P-035. Available at http://drna.pr.gov/wp-content/uploads/2015/04/El-Bosque-Estatal-de-Guil…
 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 meteorological station located in the riparian area. The met station is outfitted with a subset of the same sensors used at terrestrial sites. Measurements include wind speed and direction, air temperature, barometric pressure, relative humidity, shortwave radiation, and PAR.
A phenocam is pointed toward the land-water interface of the site. Here we show the images from the most recent hour. The full collection of images can be viewed on the Phenocam Gallery - click on the image below.
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; start permitting > 6 months prior to scheduled start.
NEON Field Operations Office
Domain 04 Support Facility
NEON Field Operations Address
45 Carr Ochoa
Guanica, Puerto Rico 00653
NEON Field Operations Phone
Dominant NLCD Classes
Evergreen Forest, Grassland/Herbaceous
USGS Geology Unit
USGS Geology Name
Lago Garzas-Anon Formations Interbedded
USGS Lithologic Constituents
Dark-red, non-pillowed andesite lava flows and volcanic breccia irregularly interbedded with hornblende-dacite-rhyodacite lava flows, sandstone-siltstone, and tuff characteristic of the Anon Formation,
USGS Geology Age
Upper Eocene (?) to Upper Campanian
Related Field Sites
Other Domain D04 Field Sites
Other Field Sites in PR