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.
From O'Geen et al., 2018:
The pine-oak forest site Soaproot Saddle is a 543-ha headwater catchment situated at the lower boundary of the rain–snow transition line. The site is representative of a midmontane, mixed-conifer ecosystem exhibiting high net primary productivity and strong seasonality with warm dry summers and cool wet winters. Mean Annual Temperature: 13.8°C. Mean Annual Precipitation: 805 mm yr−1.
Soils are mapped at the family level, consisting mainly of Holland (fine-loamy, mixed, semiactive, mesic Ultic Haploxeralfs) and Chaix (coarse-loamy, mixed, superactive, mesic Typic Dystroxerepts) series, which are representative of soils across a similar elevational band of the western Sierra Nevada. Holland has sandy loam surface texture and underlying Bt horizons with sandy clay loam textures. It is a highly weathered Ultic Halploxeralf. Red hues indicate abundance of hematite, which is indicative of a relatively intense degree of weathering. The Chaix series has sandy loam textures throughout the profile. This soil is found on landscape positions that shed water and sediment, thus erosion outpaces soil development.
Vegetation community comprises ponderosa pine (Pinus ponderosa Lawson & C. Lawson), California black oak (Quercus kelloggii Newberry), and incense cedar [Calocedrus decurrens (Torr.) Florin].
For additional information on climate and vegetation, see also Goulden et al., 2012.
Panorama of Soaproot Saddle. July 2014, shortly before major mortality event. Photo by Erin Stacy.
A full size image is available at the Sierra Nevda / San Joaquin Hydrologic Observatory digital library (external link).
An eddy-covariance flux tower was installed at this site in September 2010. Elevation of the tower is 1160 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.
Most of the hydrological monitoring infrastructure at Soaproot Saddle is located near the eddy flux tower.
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Flux Tower Transect, Soaproot Saddle - Flux Tower, Meteorology (2009-2018)
10 components • Soaproot Saddle (1000-1500 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
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.
Hundreds of instruments and sensors have been deployed in the primary SSCZO research site of the Providence Creek watershed as well as in Wolverton basin. Additional SSCZO flux towers and instruments have also been installed at the San Joaquin Experimental Range, Soaproot Saddle, and Short Hair Creek.
Explore more photos of the intstuments and sensors used by SSCZO.
Soaproot Saddle, 1100 m elevation
Quad: Shaver Lake
Bass Lake Tonalite (Kbl, formerly Tonalite of Blue Canyon)
“Medium-grained biotite-hornblende tonalite facies characterized by large euhedral hornblende prisms” (Lockwood and Bateman 1976). “Typical Bass Lake Tonalite is medium-gray, medium-grained, equigranular tonalite with a conspicuous foliation that is shown both by the preferred orientation of minerals, chiefly hornblended and biotite, and by crudely lens-shaped mafic inclusions… The color index … for most samples is 10 to 30” (Bateman 1992).
SJER, 400 m elevation
Quad: Millerton Lake
Ward Mountain Trondhjemite (Kw) (formerly Leucotonalite of Ward Mountain)
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)