Parameterization of tree-roots is essential for studies of water and energy fluxes across land surfaces. However, it is difficult to quantify the three-dimensional structure of roots. The below-ground biomass of a white fir (Abies concolor) in the Critical Zone Observatory watershed was excavated by pressurized air with minimal damage and studied using the terrestrial LiDAR remote sensing technology and image processing. Coarse roots were reconstructed digitally with a 3-dimensional modeling software (Maptek I-Site Studio), originally designed for mining applications. The objective of this study was to extract parameters such as root length, diameter, surface, volume and their horizontal and vertical distribution. Fine roots were found difficult to process with the software so these parameters were extracted using digital photography combined with image analysis tools. Coarse root distribution was found to be decreasing logarithmically with depth from 30 to 155 cm below the soil surface. Root/shoot ratio was approximately 16%, with an estimated root volume of 0.63 m3 and a shoot volume of 3.94 m3. Fine root length density was found to increase radially away from the trunk, until reaching a distance of 180 cm and then decreased out to the edge of the excavation at 400 cm. Terrestrial LiDAR was very effective for obtaining a model close to the actual coarse root architecture while image processing was better for quantifying fine roots.
Eumont, E., Hartsough, P.C., Moradi, A.B., Hopmans, J.W. (2011): Analysis of a Sierra Nevada white fir root biomass using terrestrial LiDAR and image processing . Fall meeting, American Geophysical Union, December 2011. Abstract H51A-1177. .