San Joaquin Experimental Range - SJER

Site Type

Core Terrestrial


California, D17, Pacific Southwest

Site Host

U.S. Forest Service

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NEON Sampling Boundaries
Tower Airshed Boundary
Tower Location

This map depicts the spatial layout of this field site. Please note that some locations may have moved over time due to logistics, safety and science requirements. This map was updated on April 04, 2018

Construction Status for this Site

Civil Construction Sensor Installation Field Sampling Data Status
Partially Complete
Partially Available


The San Joaquin Experimental Range (SJER) is located near the geographic center of California in the western foothills of the Sierra Nevada in Coarsegold, Madera County. SJER encompasses a total of 1806 hectares and ranges in elevation from 213-518 meters. The SJER has been designated as the core site for the Pacific Southwest.

Site history & management

The SJER is managed cooperatively by the Pacific Southwest Research Station and California State University's Agricultural Foundation. In 1934, SJER was established as California's first range research station. It was originally conceived as a cooperative interdisciplinary research center to identify cost-effect methods of commercial livestock production in the annual grass-oak pine woodlands, while maintaining the integrity of the ecosystem.


The SJER contains open woodland dominated by blue and interior live oaks and California Foothills pine (Pinus sabiniana) with scattered shrubs and nearly continuous cover of herbaceous plants. Swales occur in low areas between rises. Dominant shrub species include ceanothus (both wedgeleaf ceanothus and chaparral whitehorn) and manzanita.  Herbaceous plants are generally annuals including grasses (e.g., pine bluegrass soft chess, foxtail fescue), and various legumes. Perennials, primarily rushes, are found in the bottomlands. Native perennial bunchgrasses are uncommon and occur on north slopes.


The climate is Mediterranean. Winters are cool and wet, with frequent frosts and monthly mean temperatures between 4 and 10 °C.  The area drains into a small tributary of the San Joaquin River.  Summers are hot and dry, with maximum daily temperatures commonly exceeding 38 °C and monthly mean temperatures ranging from 24 to 27 °C.


Bedrock is mainly granitic. Soils on slopes are shallow, residual, and granitic and generally of the Ahwahnee series. Soils in swales are deeper, alluvial and generally of the Visalia series. Slope and swale soils have a relatively low water-holding capacity. Granitic outcrops are common on slopes.

Site-specific topics

NEON’s science focus for the Pacific Southwest is on a climate gradient, extending from the core site in the oak woodland at the SJER, up through an elevation gradient into mixed conifer and red fir forests. The low density of cattle, light grazing management and fire management are also representative of land use practices throughout the extent of this ecosystem. This core site provides:

  • A representative wildland to contrast the design of the relocatable sites
  • Statistical power for regional-scale understanding
  • A robust design to address expected future changes in climate that are, in turn, expected to influence biodiversity, biogeochemistry, and infectious and invasive species biology

Research history

Databases maintained at the SJER include:

  • Long-term climate information
  • Publications based on information acquired at the forest
  • Spring bird counts beginning in the mid-1980s
  • Long-term acorn production censuses
  • Grazing intensity information.

More than 500 scientific publications have emerged from work at the SJER ranging from studies on fire ecology to sulfur fertilization. Learn more about the SJER's history here.

Resources & additional readings

Dialog content.