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.
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.
Some of the biogeochemical studies conducted at the CZO by grad students, post docs, PIs and collaborators, include:
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.
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.
For additional information contact Erin Stacy.
30 Oct 2017 - Water Resources Research published a new special collection in September 2017 featuring concentration-discharge research from multiple CZOs.
06 Apr 2017 - 2017 CZO Webinar Series: Critical Zone and Society.
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,...
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.
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.
20 Dec 2016 - Lawrence Livermore and UC Merced researchers are tracking water through the critical zone using cutting-edge technology and new collection methods.
19 Oct 2016 - University of Nevada Reno's Adrian Harpold reflects on his past and present time researching at Critical Zone Observatories.
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.
0.992 km2, 1790-2117 m elevation,
1.323 km2, 1731-2025 m elevation,
0.487 km2, 1768-1983 m elevation,
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.
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.
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.