GPR is an electromagnetic imaging technique that can be used to detect buried objects or hidden structures. GPR has been used for geological research, archaeology, forensics, and for assessing the integrity of roads and bridges. FS researchers soon recognized the potential for using the technology in forest-based research.

Measuring the belowground growth of trees is essential to understanding forest productivity and carbon allocation. Estimating the biomass of tree roots traditionally involves using soil cores, pits, and trenches--digging up roots, then sieving, washing, drying, and weighing them. These methods are destructive, labor-intensive, and not very useful for measuring the lateral extent of a root system.

In the September/October issue of the Soil Science Society of America Journal (SSSAJ), researchers from the FS Southern Research Station (SRS) unit in Research Triangle Park, NC present the results of a study that assesses ground penetrating radar (GPR) as a fast, noninvasive method to improve estimates of root biomass.

"Knowing both the volume and extent of root systems is important in the carbon sequestration studies we do," says Kurt Johnsen, director of the SRS Biological Foundations of Southern Forest Productivity and Sustainability unit, and co-author of the article with John Butnor and Lance Kress. "Many of the forests in the Southeast grow on land where the soil carbon has been depleted by former farming practices. In these forests, tree roots are the most dynamic pool for carbon accumulation below the ground."

For the carbon flux experiments that Johnsen and fellow researchers conduct at the Free Air Carbon Dioxide Enrichment (FACE) sites in the Duke Forest, they use a so
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Contact: John Butnor
jbutnor@fs.fed.us
802-951-6771 x1230
Southern Research Station - USDA Forest Service
23-Sep-2003