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2488983 
Journal Article 
Estimating coarse root biomass with ground penetrating radar in a tree-based intercropping system 
Borden, KA; Isaac, ME; Thevathasan, NV; Gordon, AM; Thomas, SC 
2014 
Yes 
Agroforestry Systems
ISSN: 0167-4366
EISSN: 1572-9680 
88 
4 
657-669 
WOS:000340049800009 
Conventional measurements of tree root biomass in tree-based intercropping (TBI) systems can be inadequate in capturing the heterogeneity of rooting patterns or can be highly destructive and non-repeatable. In this study, we estimated coarse root biomass using ground penetrating radar (GPR) of 25-year-old trees inclusive of five species (Populus deltoides x nigra clone DN-177, Juglans nigra L., Quercus rubra L., Picea abies L. Karst, and Thuja occidentalis L.) at a TBI site in Southern Ontario, Canada. Subsurface images generated by GPR were collected in grids (4.5 x 4.5 m) centred on tree stems. The predictive relationship developed between GPR signal response and root biomass was corrected for species effects prior to tree-scale estimates of belowground biomass. Accuracy of the tree-scale estimates was assessed by comparing coarse root biomass measured from complete excavations of the corresponding tree. The mean coarse root biomass estimated from GPR analysis was 54.1 +/- A 8.7 kg tree(-1) (mean +/- A S.E.; n = 12), within 1 % of the mean coarse root biomass measured from excavation. Overall there was a root mean square error of 14.4 kg between measured and estimated biomass with no detectable bias despite variable conditions within the in-field and multi-species study. Root system C storage by species, calculated with species-specific root carbon concentrations, is estimated at 5.4 +/- A 0.7-34.8 +/- A 6.9 kg C tree(-1) at this site. GPR is an effective tool for non-destructively predicting coarse root biomass in multi-species environments such as temperate TBI systems. 
Temperate agroforestry; Belowground biomass; Root detection; Geo-imaging; Tree root system; Volatile carbon; Carbon storage