The Calhoun CZO features long-term plot and watershed experiments. Data from sensor networks; gas, water, and solid samples; geophysical measurements; and models will be used to evaluate CZ evolution following severe erosion and land degradation. Observational data sets are being developed via three major infrastructure projects: 1) Re- and up-instrumentation of three historic experimental catchments; 2) Inverted tower installation for atmospheric and deep-profile sampling; and 3) Sub-surface sensor installations in space-for-time land-use plots.
Re- and Up-Instrumented Experimental Watersheds
Three experimental watersheds that operated for more than ten years between 1947 and 1962 will be re-instrumented to test effects of 60-years of reforestation on severely eroded and gullied watersheds. Old strip charts from rain and stream gages are being digitized with help from USGS in Atlanta.
Atmosphere to Bedrock Instrumentation
A flux tower will be built to estimate forest-atmosphere dynamics of energy, water, and CO2 and forest-bedrock dynamics of water, CO2, and other gases. The instrumentation has three components: 1) an above-canopy eddy covariance (EC) system for direct measurement of above-canopy fluxes of energy, water and carbon (CO2), 2) a below-canopy radiation and meteorological sensor system which in conjunction with a Maximum Entropy Production (MEP) modeling will estimate tree-scale above- and under-canopy energy and water fluxes, and 3) co-located below-ground sensors and samplers for measurement of gases (CO2 and O2), soil moisture, and temperature at multiple depths as deeply as they can be installed.
Old-field and Uncultivated Forest Comparisons
At four research areas, paired hardwood stands (uncultivated hillslopes to small watersheds) and old-fields will be instrumented with co-located below-ground sensors and samplers for measurement of gases (CO2 and O2), soil moisture, and temperature at multiple depths as deeply as they can be installed.
08 Jul 2019 - CZO will end Nov 2020, succeeded by the “CZ Collaborative Network”. Let’s explore how the CZ community can build upon the CZOs via new NSF proposals.
14 Nov 2018 - How critical zone science unearths secrets: The new cross-disciplinary field of study concerns itself with the living skin of the Earth.
01 May 2017 - Anna Wade (visiting from Duke University) and Jay Austin (based at the University of Georgia) are collaborating by using X-ray Diffraction (XRD) to...
21 Nov 2016 - Four soil pits were installed in new Research Area 8 at the Calhoun CZO on 21-22 November 2016 for easy access for soil sampling down to 2 meters.
17 Oct 2016 - Eight soil pits were installed at the Calhoun CZO on 17-18 October 2016 for easy access for soil sampling down to 2 meters. Photo: Will Cook.
03 Oct 2016 - Just posted, thanks to efforts of Don Nelson, Kathy O'Neill, Mike Coughlan, Michael Lonneman, Zachary Meyers, and many other students, is an...
17 Aug 2016 - On August 17, 2016 a crew from Georgia Tech led by graduate student Yao Tang and professor Jingfeng Wang, with a little help from the folks at Duke,...
14 Jul 2016 - Another Calhoun CZO record - gas reservoirs installed at 8.5m depth! Jay Austin, Zach Brecheisen, and Dan Richter only stopped at 8.5m because they...
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.
15 Sep 2016 - At long last, a 900 sq ft house is now our headquarters at the Calhoun!!! We should all start to use it for multi-day, 2-day, & even 1-day...
13 Jul 2016 - On July 13, 2016, Duke PhD candidate Zach Brecheisen, with assistance from his advisor Dan Richter and Jay Austin, installed TDR probes at 25-cm...
04 Dec 2015 - Taking the Pulse of the Earth's Surface Systems In September of 2014, Laurel Larsen (UC Berkley), Elizabeth Hajek (Penn State), and others...
134-190 m elevation, 16 °C, 1250 mm/yr
The Calhoun Critical Zone Observatory is comprised of eight research areas in the Calhoun Experimental Forest and surrounding areas in the Sumter National Forest in upstate South Carolina, including the Holcombe's Branch watershed, experimental catchments, and space-for-time (paired hardwood-pine-cultivated field) plots. The areas were chosen primarily for their wealth of historical data giving researchers an ideal platform for testing hypotheses on how critical zones evolve in response to human forcings at the landscape scale.
6.5 km2, 108-195 m elevation, 16 °C, 1250 mm/yr
0.40 km2, 180-190 m elevation, 16 °C, 1250 mm/yr
16 °C, 1250 mm/yr
180-190 m elevation, 16 °C, 1250 mm/yr
134-157 m elevation, 16 °C, 1250 mm/yr