ACES is a dynamic system that uses an open, flow-through design to measure carbon dioxide as it is emitted from the forest floor or from the woody tissue of trees. The system uses a series of chambers and pumps to maintain a constant flow and evacuation of air. Sixteen soil chambers are measured sequentially using a single infrared gas analyzer and a datalogger. Since chambers are constantly cleared when not being sampled, the carbon dioxide does not build up in the soil sample and skew the readings, as it does in the static chambers used in previous systems. ACES runs continuously and is fully automatic, requiring only calibration checks twice a week.
ACES units are being used in several long-term ecological studies to collect data on a continuous basis across the southeastern United States. Current research cooperators include: Duke University (Durham, NC), USDA Agricultural Research Service (Auburn, AL), the SRS Center for Forested Wetlands Research (Charleston, SC), SRS Disturbance and Management of Southern Pine Ecosystems unit (Athens, GA), Auburn University (Auburn, AL), Westvaco Corporation, and International Paper Corporation.
ACES units have also been used in a variety of short-term studies in the United States and Canada, including black spruce plantations in the Petawawa Experimental Forest (Deep River, ON), native fir/pine ecosystems in the Teakettle Experimental Forest (east of Fresno, CA), and old-growth forests in the Pacific Northwest (Wind River Canopy Crane, near Stevenson, WA).
"We have now built 17 ACES that we have used in cooperative research projects across the country," says Kurt Johnsen, project leader of the Research Triangle Park unit. "We worked hard to develop and test this system. Now that it is patented, we hope the technology will be used in even more forested ecosystems, so that our knowledge of and ability to predict forest carbon cycling will increase even more rapidly."