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.
06 Apr 2017 - 2017 CZO Webinar Series: Critical Zone and Society.
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...
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...
05 Nov 2015 - Dan Richter has been excavating soils profiles up and down the banks of Holcombe's Branch in the Calhoun historic watersheds area, which will...
13 Oct 2015 - The Calhoun CZO received nearly 25 cm rain in 24-hr Sunday 4 October. Paul Schroeder shot a photo of Ryan Fimmen's 2004 "Tyger Stripe"...
Calhoun Research Area 8, the newest and easternmost of the 8 CCZO research areas, includes adjacent pine and hardwood stands.
Calhoun Research Area 7, located south of the Enoree River, includes adjacent pine and hardwood stands. This is the southernmost of the 8 CCZO research areas.
Research Area 6 is centered on the historic Rose Hill Plantation, home of South Carolina's secessionist governor William Henry Gist (1807-1874).
Calhoun Research Area 5, located at the corner of Old Buncombe and Sardis Roads, includes adjacent pine and hardwood stands.
One of four historic Calhoun experimental catchments, which were instrumented with precipitation and runoff gauges from the 1940s to 1960s. The catchment was severely eroded and gullied and has been reforested over the last half century. The archived hydrologic records and photographs have been stored in the Coweeta Hydrologic Laboratory data vault since 1962. Contemporary hydrologic responses of the catchments will be compared with the historical data.
0.40 km2, 180-190 m elevation, 16 °C, 1250 mm/yr
The largest of the research areas at the Calhoun, this includes three major subsections: (1) the Calhoun Long-Term Soil-Ecosystem Plots and Reference Areas, (2) the "tower site" (site of future flux tower and clearcut treatment), and (3) the "dove field", which to our knowledge has been continuously cultivated since at least the 1930s. Also included in Research Area 1 is a 70-m deep well in a cow pasture on private land adjacent to the long-term plots.
16 °C, 1250 mm/yr
180-190 m elevation, 16 °C, 1250 mm/yr
134-157 m elevation, 16 °C, 1250 mm/yr
Three historic Calhoun experimental catchments are being re- and up-instrumented based on precipitation and runoff gauging from the 1940s to 1960s. The catchments were severely eroded and gullied and have been reforested over the last half century. The archived hydrologic records were stored in the Coweeta Hydrologic Laboratory data vault since 1962. Contemporary hydrologic responses of the catchments will be compared with those that are historic. The three experimental catchments reside within the much larger Holcombe's Branch, a tributary of the Tyger River. The Holcombe's Branch basin will be used to examine the erosion's interactions with soil carbon gains and losses.