and buried organic debris, assess root size, map root distribution, and estimate root biomass (But-nor et al., 2001, 2003; Stover et al., 2007). Being non-invasive and non-destructive, GPR allows repeated measurements that facilitate the study of root system development. Roots as small as 0.5 cm in diameter have been detected at depths of less than 50 cm with a 1500 MHz antenna in well drained, coarse-textured soils (Butnor et al., 2003). There has been considerable interest in mapping tree root systems to understand root architecture and soil volume utilization (Cermak et al., 2000; Hruska et al., 1999; Stokes et al., 2002). However, without intensively detailed, methodical scanning of small grids, it is not possible to separate roots by size class or depth (Wielopolski et al., 2000). Orientations of roots, geometry of root reflective surfaces, and proximity of other adjacent roots presently confound attempts to delineate root size classes in forest soils. In addition, this methodology cannot determine differences in species within a mixed stand.

We present the results of two case studies conducted in Florida which were aimed at determining tree root biomass with GPR in a pine plantation and a native scrub-oak shrubland ecosystem to highlight the technical considerations, successes, and examples of where clutter confounded meaningful interpretation.

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