Assessing corewood acoustic velocity and modulus of elasticity with two impact based instruments in 11-year-old trees from a clonal-spacing experiment of Pinus radiata D. Don

Abstract Outermost wood and whole stem modulus of elasticity ( E ) was measured acoustically from trees within an 11-year-old Pinus radiata experiment, which included six clones grown at two contrasting stand densities (833 and 2500 stems ha −1 ). This study examines the effect of bark removal on whole stem E as measured by resonance ( E res ) in the lower log (0–2 m) and how branch removal influences E res in the upper log (2 m to 70% tree height). An additional objective was to develop relationships between E of the outer part of the wood made on standing trees, using time of flight ( E tof ), and whole stem E measured using resonance ( E res ). Both branch and bark removal significantly influenced E res , increasing values by an average of 8.3% and 5.4%, respectively. The influence of bark on E res was relatively constant across the E range examined, ranging from 8.0% at low values of E res (2.6 GPa) to 8.6% at high values of E res (5.5 GPa), with bark. In contrast, increases in E res induced by branch removal ranged from 24% at low values of E res (3.4 GPa) to 0% at high values of E res (6.5 GPa). There were strong positive linear relationships between E tof and E res , both when bark was present ( r 2  = 0.94) and removed ( r 2  = 0.92), from the whole stem. Values of E res measured with and without bark, were respectively on average 38% and 33%, lower than E tof (with bark). Although stand density and tree diameter did not significantly influence these equations the relationship between E tof and E res logs with bark attached was significantly influenced by clone ( P P E tof measurements on standing trees in predicting whole stem E res , and also suggest that it is important to account for the effect of bark and branches when measuring whole stem E using acoustic methods.