Non-destructive wood density assessment of Scots pine (Pinus sylvestris L.) using Resistograph and Pilodyn

We tested two methods for non-destructive assessment of wood density of Scots pine standing trees: one based on penetration depth of a steel pin (Pilodyn) and the other on micro-drilling resistance (Resistograph). As a benchmark we used wood density data from x-ray analysis (SilviScan). We assessed in total 622 trees of 175 full-sib families growing in a single progeny test. Pilodyn was applied with bark (PIL) and without bark (PIL(B)). Raw Resistograph drilling profiles (RES) were adjusted (RES(TB)) in order to eliminate increasing trend caused by needle friction. Individual narrow-sense heritability of benchmark SilviScan density (DEN; 0.46) was most closely approached by that of adjusted RES(TB) (0.43). Heritabilities were lower for unadjusted RES (0.35) as well as for PIL and PIL(B) (both 0.32). Additive genetic correlations of the benchmark DEN with RES, RES(TB), PIL and PIL(B) were 0.89, 0.96, 0.59 and 0.71, respectively. Our results suggest that Resistograph is a more reliable tool than Pilodyn for wood density assessment of Scots pine; however, we highly recommend adjusting Resistograph drilling profiles prior to further analyses.