Preliminary Evaluation of Bending Properties in Dimension Lumber of Paulownia tomentosa as a Fast-Growing Tree Species in Japan

The aim of this study is to evaluate the possibility of re-establishment of the Paulownia tomentosa (Thunb.) Steud. forestry and wood industry for sustainable wood production in Japan. Bending properties were preliminarily investigated for dimension lumber (2 by 4, 38 by 89 mm in transverse section) and small-clear specimens of this species. The severe slope of grain in lumber reduced the modulus of rupture (MOR) and disturbed the relationship between the modulus of elasticity (MOE) and MOR. Preliminary studies determined a 5 percent lower tolerance limit with a 75 percent confidence level in MOR of lumber was 12.1 MPa. The value exceeded the characteristic value of MOR of 2 by 4 lumber in structural grade Western redcedar ( Thuja plicata ).