EFFECT OF ELEVATED CO 2 ON COARSE‐ROOT BIOMASS IN FLORIDA SCRUB DETECTED BY GROUND‐PENETRATING RADAR

Growth and distribution of coarse roots in time and space represent a gap in our understanding of belowground ecology. Large roots may play a critical role in carbon sequestration belowground. Using ground‐penetrating radar (GPR), we quantified coarse‐root biomass from an open‐top chamber experiment in a scrub‐oak ecosystem at Kennedy Space Center, Florida, USA. GPR propagates electromagnetic waves directly into the soil and reflects a portion of the energy when a buried object is contacted. In our study, we utilized a 1500 MHz antenna to establish correlations between GPR signals and root biomass. A significant relationship was found between GPR signal reflectance and biomass ( R 2 = 0.68). This correlation was applied to multiple GPR scans taken from each open‐top chamber (elevated and ambient CO 2 ). Our results showed that plots receiving elevated CO 2 had significantly ( P = 0.049) greater coarse‐root biomass compared to ambient plots, suggesting that coarse roots may play a large role in carbon sequestration in scrub‐oak ecosystems. This nondestructive method holds much promise for rapid and repeatable quantification of coarse roots, which are currently the most elusive aspect of long‐term belowground studies.