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San Joaquin Experimental Range (210-520 m elevation)

Field Areas     


The San Joaquin Experimental Range (SJER) research site is in the oak woodland foothills of the southern Sierra Nevada.

SJER field area. Photo by Erin Stacy.


igneous-felsic intrusive

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Setting & Research
Dynamic Map
Partner Organizations
  • Setting & Research

    This site is part of an elevational transect that increases in altitude from west to east.

    Sites include San Joaquin Experimental Range, Soaproot Saddle, Providence Creek Headwater Catchments, and Short Hair Creek, spanning a 2300-m elevation range that captures gradients in climate, regolith, soils, and vegetation. Along this transect, bedrock lithology is generally constant (intrusive felsic plutons). Ecosystems range from low-elevation oak savannah (rain-dominated) to high-elevation subalpine forest (snow-dominated). A series of eddy-covariance gas flux towers are installed at these sites (see below). Examples of transect-length work include soil and regolith depth, chemistry, and moisture characterizations; vegetation surveys; forest water-balance research; and wind-blown dust geochemistry and microbiology studies.

    Climate, Landscape, Soils, Vegetation

    From O'Geen et al., 2018:

    The oak savannah San Joaquin Experimental Range is the driest and warmest site out of our field areas. Mean Annual Temperature: 16.6°C. Mean Annual Precipitation: 513 mm yr−1.

    Rolling hills at the site serve as small, localized catchments (typically <1 ha) that feed ephemeral streams.

    Soils are classified as Ahwahnee (coarse-loamy, mixed, active, thermic Mollic Haploxeralfs), Vista (coarse-loamy, mixed, superactive, thermic Typic Haploxerepts), or Auberry (fine-loamy, mixed, semiactive, thermic Ultic Haploxeralfs) series. The extent of weathering and pedogenesis is low. Soils are coarse textured (loamy sands and sandy loams), shallow to moderately deep (Beaudette and O’Geen, 2016). 

    Vegetation community comprises scattered blue oak (Quercus douglasii Hook. & Arn.) and interior live oak (Quercus wislizeni A. DC.) with naturalized annual grass understory.

    For additional information on climate and vegetation, see also Goulden et al., 2012.

    Panorama of San Joaquin Experimental Range. May 2014.

    A full size image is available at Sierra Nevada / San Joaquin Hydrologic Observatory digital library (external link).

    Active Instrumentation
    Flux Tower

    An eddy-covariance flux tower was installed at this site in October 2009. Elevation of the tower is 405 m above sea level.

    The flux tower is used to analyze the carbon and water balance of the surrounding forest. Instruments on the flux tower track changes in carbon dioxide, water vapor, air temperature, relative humidity, and other atmospheric properties.

    Panorama of San Joaquin Experimental Range. May 2014.

    A full size image is available at Sierra Nevada / San Joaquin Hydrologic Observatory digital library (external link).

  • Dynamic Map

    To fully zoom into a small area, you may need to visit the "Map" button and uncheck "Terrain" view.

  • Data

    Flux Tower Transect, SJER - Flux Tower, Meteorology (2009-2018)
    10 components    San Joaquin Experimental Range (210-520 m elevation)    Biology / Ecology, Climatology / Meteorology    Mike Goulden; Anne Kelly

    National - Flux Tower - AmeriFlux Network data (2007-2018)
    14 components    Boulder Creek Watershed, Jemez River Basin, Reynolds Creek Experimental Watershed, Susquehanna Shale Hills Critical Zone Observatory, San Joaquin Experimental Range (210-520 m elevation), Soaproot Saddle (1000-1500 m elevation), Short Hair (2670 m elevation)    Climatology / Meteorology    Boulder Creek Critical Zone Observatory; Catalina-Jemez Critical Zone Observatory; Reynolds Creek Critical Zone Observatory; Shale Hills Critical Zone Observatory; Southern Sierra Critical Zone Observatory

  • Photos

    SSCZO - SJER field area

    This gallery showcases the landscape, vegetation, equipment and facilities at the SJER field area. 

    SSCZO - Flux Towers

    An eddy covariance flux tower is located near the top of the P301 watershed. Instruments collect data on temperature, relative humidity, and fluxes of carbon dioxide and water vapor to determine the physiological responses of the site (for example, how photosynthesis increases with light) and summed over a year to determine the carbon balance of a site (how much carbon it is gaining or losing). Three other flux towers have been instrumented at different elevations with the Sierras including the San Joaquin River, Soaproot, and Short Hair Creek.

    This west-east transect spans elevation gradient from 400 m to 2700 m. The change in elevation is accompanied by a slight increase in precipitation, but the main change is a shift from rain-dominated precipitation to snow-dominated precipitation. The climatic shift plays out in other ways as well. At lower elevations, high temperatures and low water availability limit evapotranspiration by vegetation. Meanwhile, forest activity (evapotranspiration) at higher elevations is limited by cold winter temperatures. There is a sweet spot at middle elevations of yera-round evapotranspiration and forest activity.

    Photo galleries of each flux tower are available: San Joaquin Experimental Range;  Soaproot SaddleProvidence subcatchment P301; and Short Hair Creek.

  • Partner Organizations

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  • Geology

    • igneous-felsic intrusive

    SJER – 400 m elevation
    Quad: Millerton Lake

    Ward Mountain Trondhjemite (Kw) (formerly Leucotonalite of Ward Mountain)
    “Medium- to fine-grained biotite leucotonalite (trondhjemite). Rock appears gneissic in outcrop and deformed and recrystallized in thin section... Biotite, generally in tiny plates, is the sole primary mafic mineral. Secondary muscovite in plates as much as 2 mm across is abundant locally... U-Pb age of … 115 m.y” (Bateman and Busacca 1982). “Biotite averages about 10 percent of the rock… most samples contain less than 5 percent alkali feldspar… Deformed trondhjemite, which constitutes the bulk of the rock, is fine grained and gneissic, and when viewed in thin section it can be seen to have a granoblastic texture… The Ward Mountain Trondhjemite intrudes the Bass Lake Tonalite” (Bateman 1992).

    Soaproot Saddle, 1100 m elevation
    Quad: Shaver Lake
    Bass Lake Tonalite (Kbl, formerly Tonalite of Blue Canyon)

    P301, 2000 m elevation
    Quad: Huntington Lake
    Dinkey Creek Granodiorite (Kdc, formerly Granodiorite of Dinkey Creek)

    Short Hair Creek, 2700 m elevation
    Quad: Blackcap Mountain
    Aplite and felsic quartz monzonite dikes (Kap)
    Granodiorite of Dinkey Creek (Kdc, see description for P301)