INFRASTRUCTURE

The Southern Sierra CZO infrastructure consists of well-instrumented field sites, data and other resources for carrrying out field research, and associated data analysis and modeling. The main contact for questions about our field infrastructure is our Field Manager, Erin Stacy.

© Southern Sierra Critical Zone Observatory

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Southern Sierra CZO Infrastructure

Evapotransipration studies

There are currently 4 eddy covariance flux towers in operation at different elevations along an E-W transect of the Southern Sierra Nevada, including: San Joaquin Experimental Range (SJER) (420 m), Soaproot Saddle (1080 m), Providence CZO (1950 m), and Shorthair Creek (2670 m). The change in climate of the 4 flux towers will allow us to investigate interactions between climate, soil development, species distribution, biotic production, and hydrological balance.

Flux towers provide individual measurements of water, energy and carbon exchange with the atmosphere. This data is then extended outward using the meteorological, snow/soil, remotely sensed and other spatial data to understand broader interactions at different scales. Tower instruments also provide an measure of evapotranspiration and net ecosystem productivity. Data within the embedded wireless network use the Providence flux tower as the main transmission hub for wireless sensor network.

Two Cosmic-ray Soil Moisture Observing Systems (COSMOS) were co-located with the P301 and Shorthair flux towers in June 2011. COSMOS is an advanced technology used to measure soil water content over large areas. This is a collaboration with the University of Arizona.


CZO tree experiments

In August 2008 we instrumented a mature white fir (Abies concolor) and the surrounding soil to better define the water balance in a single tree. In July 2010, we instrumented a second tree, a Ponderosa pine (Pinus ponderosa) in shallower soils on a drier, exposed slope. Sap-flow measurements in the trunk and stem-water-potential measurements in the canopy capture the seasonal cycles of soil wetting and drying. See time lapse photos of snow around the tree in 2008-09.

The objectives of this study are to 1) monitor surface and subsurface water budgets in remote landscapes, with specific attention to moisture and temperature variability in near surface soils and 2) study the interactions between soil hydrology and tree functioning in a forested catchment, as part of a wider effort to analyze changing ecosystem response to changing environmental inputs.

In September 2010 a root excavation was conducted on a white fir adjacent to the first Critical Zone tree. Excavation was performed to map the root structure and location in response to new questions regarding moisture deficit in the soil profile. Excavation allows us to confirm the lateral and vertical extent of the root system and provide a better estimate of the area of influence of moisture removal for the tree. See images of the excavation here (Google login required).

For additional information contact Pete Hartsough.


Biogeochemistry

Some of the biogeochemical studies conducted at the CZO by grad students, post docs, PIs and collaborators, include:

  • The use of snow melt plots to determine which soil biogeochemical processes are most likely to be impacted by climate change across the rain-snow transition zone.
  • Carbon cycling and organic matter stabilization as affected by erosion.
  • Estimating the response of gaseous fluxes to climate change using an N isotope mass-balance model in order to determine how the rain-snow transition zone affects N cycling in the plant-soil system.
  • Investigation of nutrient hotspots and O horizon runoff in soils.

For additional information contact Steve Hart or Asmeret Asefaw Berhe.


Surface-Groundwater interactions

The objective of this experiment is to determine variations in diel temperature change, inflow and outflow of groundwater into the stream, quantify interactions between vegetation and water, and understand the water balance and hydrologic processes. Experiments are being conducted in both the P301 meadow and at Long Meadow in Sequoia National Park.

Groundwater exchange in P301 meadow includes the installation of 24 wells and piezometers, 2 stilling wells, and 3 three sap rock piezometers to a depth of 205 to 500 cm. Evapotranspiration chamber measurements commenced in June 2010, continuing in Fall 2011 in order to understand ET throughout the growing season. Salt dilutions have commenced at the installed stilling wells to measure flow and establish a rating curve.

Activities in Long meadow, Sequoia NP began in 2007. Long Meadow is within the Wolverton area of the park. Research has focused on exploiting temperature as a hydrologic tracer using a distributed temperature sensor (DTS) and Tidbit temperature sensors, plus data from piezometers and observation wells. The DTS system includes a computer, two 1-km long fiber optic cables and a power source. The DTS deployment led to the observations of polymictic pool behavior in the meadow pools. This daily thermal stratification and nightly was further assessed in 2008 and 2009 using Hobo Tidbit temperature loggers, for vertical temperature profiles, and Radon-222 analysis.

In addition to temperature and geochemical tracer activities, evapotranspiration (ET) and ground water level and pressure head measurements have so far been collected from 2008-2011.


Weathering and Geophysical studies

Spearheaded by colleagues at the University of Wyoming, researchers have been participating in a number of weathering studies investigating long-term versus short-term rates of erosion (sediment basins and solute fluxes versus cosmogenic nuclides and regolith geochemistry), landscape evolution, “stepped topography” and the role of bare rock in shaping landscapes, the role of dust in pedogenesis and nutrient supply to the forests in and around the CZO (from isotopic tracers), and the origins of coarse sediment in streams (also from isotopic tracers).

Geophysical imaging of weathered layers at the CZO has been studied over the past two summers to provide 2D and 3D knowledge of the subsurface. Methods of geophysical investigation include seismic refraction and resistivity. Tests on hypotheses include what controls the thickness of the subsurface (weathering and erosion), and how much water is stored in the subsurface (porosity versus depth).

Future studies focus on cosmogenic nuclide method development (10Be in magnetite), drilling and coring in partnership with DOSECC (Drilling, Observation and Sampling of the Earths Continental Crust).

For additional information contact Clifford Riebe.

Wireless sensor networks

In the Fall of 2007 a 28-node sensor network was deployed around the upper and lower met stations in P300, the main CZO catchment. On N-S aspects sensors were placed and under canopy, at the canopy drip edge and in the open. In the Fall of 2008 a 50-node wireless embedded sensor network was deployed across varying aspects, elevations, and canopy covers to capture spatial and temporal variations of snow depth, soil temperature and soil volumetric water content in the P301 headwaters of Providence Creek. Over 300 sensors are included in this deployment. For more information on the wireless sensor networks, read a case study on Dust networks (pdf).

For additional information contact Erin Stacy.


© Southern Sierra Critical Zone Observatory

© Southern Sierra Critical Zone Observatory

© Southern Sierra Critical Zone Observatory

© Southern Sierra Critical Zone Observatory

© Southern Sierra Critical Zone Observatory

Infrastructure News

FEATURED NATIONALLY

Water Resources Research Special Collection: Concentration-discharge relations in the critical zone

30 Oct 2017 - Water Resources Research published a new special collection in September 2017 featuring concentration-discharge research from multiple CZOs.

FEATURED

2017 CZO Webinar Series: Critical Zone and Society

06 Apr 2017 - 2017 CZO Webinar Series: Critical Zone and Society.


Visiting the Water Source: A Tour of the Kings River Headwaters

06 Nov 2017 - By Michelle Gilmore and Leigh Bernacchi   Ever wonder how we know what we know about water? Twenty-five intrepid water and forest managers,...

New SSCZO comic artfully communicates research

19 Jul 2017 - Wonder what soils and sponges have in common? Or why some trees in the Sierra Nevada are dying while others are surviving? Find out in our new comic.

Gobi Desert Dust Helps Sustain California’s Sierra Nevada

28 Mar 2017 - A team of researchers found that dust provides a much greater amount of nutrients to vegetation in the Sierra Nevada than previously thought.

Pushing the Limits on Water Isotope Measurement:  Lawrence Livermore and UC Merced

20 Dec 2016 - Lawrence Livermore and UC Merced researchers are tracking water through the critical zone using cutting-edge technology and new collection methods.

Critical Zone Q&A with researcher Adrian Harpold

19 Oct 2016 - University of Nevada Reno's Adrian Harpold reflects on his past and present time researching at Critical Zone Observatories.

More News >


Field Areas:

Providence Creek headwater catchments

4.6 km2, 1660-2117 m elevation, 8 °C, 1200 mm/yr

The primary Southern Sierra CZO research area is the Providence Creek headwaters, located on the North Fork of the Kings River. The Providence Creek headwaters area varies in elevation from 1660 to 2115 meters. This 4.6 square kilometer catchment is designated as P300. Nested within the P300 catchment are three subcatchments, designated as P301, P303 and P304.

Providence Creek Subcatchment P301

0.992 km2, 1790-2117 m elevation,

P301 Meadows

Critical Zone Tree 1

0.0001 km2,

Providence Creek Subcatchment P303

1.323 km2, 1731-2025 m elevation,

Providence Creek Subcatchment P304

0.487 km2, 1768-1983 m elevation,


Flux Towers Transect

Transect area: 568 km2, 405-2700 m elevation,

The Southern Sierra CZO operates eddy co-variance flux towers installed at four different locations varying from 405-2700 meters.

405 m Flux Tower, San Joaquin Experimental Range

513 mm/yr

1160 m Flux Tower, Soaproot Saddle

805 mm/yr

2015 m Flux Tower, Providence Creek subcatchment P301

1015 mm/yr

2700 m Flux Tower, Short Hair Creek

1078 mm/yr


Wolverton Basin

8 km2, 2230-2700 m elevation,

The Southern Sierra CZO conducts additional research in the Wolverton basin, located at an elevation of 2230-2700 meters, in Sequoia National Park.


Other instrumented sites

Three additional sets of instrumented sites are available in the Southern Sierra for comparative research: these include the Kings River Experimental Watershed (KREW) project, sites in the Sierra Nevada Adaptive Management Project (SNAMP), and the America River Observatory.