The San Joaquin Experimental range is located approximately 20 miles north of Fresno, CA. The site sits at 210-520 m above sea level, in the foothills of the Sierra Nevada mountains. The area is mainly grassy open oak woodland, and drains into the San Joaquin River basin. 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. This core site provides: A representative wildland to contrast the design of the relocatable sites, Statistical power for regional-scale understanding, robust design to address expected future changes in climate that are, in turn, expected to influence biodiversity, biogeochemistry, and infectious and invasive species biology.

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 20 miles south, and Coarsegold/Oakhurst 15 miles north. The site includes a 127' tall flux tower and an underground soil array surrounded by observational sampling plots for plants, animals, soils and microbes.