Abstract

The quality of dimension lumber (2 by 4 lumber) was preliminarily investigated in four common Mongolian softwoods: Pinus sylvestris L., Pinus sibirica Du Tour, Picea obovata Ledeb., and Larix sibirica Ledeb. to produce high quality dimension lumber for structural use. In total 61, 39, 67, and 37 pieces of lumber were prepared for Pinus sylvestris, Pinus sibirica, Picea obovata, and L. sibirica, respectively. The lumber was visually graded and then tested in static bending to obtain the 5% lower tolerance limits at 75% confidence level (f0.05) of the modulus of elasticity (MOE) and the modulus of rupture (MOR). In addition, the effects of sawing patterns on bending properties were also analyzed. The f0.05 of the MOE and MOR were 4.75 GPa and 15.6 MPa, 3.39 GPa and 11.0 MPa, 3.78 GPa and 11.7 MPa, and 6.07 GPa and 22.3 MPa for Pinus sylvestris, Pinus sibirica, Picea obovata, and L. sibirica, respectively. These results suggested that with a few exceptions, characteristic values of MOR in the four common Mongolian softwoods resembled those in similar commercial species already used. In visual grading, over 80% of total lumber was assigned to select structural and No. 1 grades in Pinus sylvestris and Pinus sibirica, whereas approximately 40% of total lumber in L. sibirica was No. 3 and out of grades. Sawing patterns affected bending properties in Pinus sylvestris and L. sibirica, but did not affect Pinus sibirica and Picea obovata. Dynamic Young's modulus was significantly correlated with bending properties of dimension lumber for the four species. Based on the results, it was concluded that dimension lumber for structural use can be produced from the four common Mongolian softwoods.

Highlights

  • In Mongolia, coniferous tree species occupy over 70% in total forest area of 11.5 million hectares [1]

  • These results indicated that among the four species, crook and bow were severe in Pinus sibirica, and twist was severe in L. sibirica, followed by Picea obovata

  • In the present study, dimension lumber qualities were investigated for four common Mongolian softwood species, Pinus sylvestris, Pinus sibirica, Picea obovata, and L. sibirica

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Summary

Introduction

In Mongolia, coniferous tree species occupy over 70% in total forest area of 11.5 million hectares [1]. 62.5%, and the other species, including Pinus sylvestris L., Pinus sibirica Du Tour, and Picea obovata Ledeb., cover 9.8% [1]. Wood from these four species are considered as Mechanical properties of structural lumber, such as dimension lumber, have been investigated for softwood species by many researchers [3,4,5,6,7,8,9,10,11,12,13]. Dahlen et al [16] reported that the f0.05 values for Southern pine (Pinus spp.) were 5.8 to 8.2 GPa and 13.0 to 23.0 MPa for MOE and MOR, respectively, in dimension lumber (No 2 grade in visual grading) for 2 by 6, 2 by 8, Sarkhad et al J Wood Sci (2020) 66:72

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