Physical and Mechanical Properties of Liquidambar styraciflua as a Potential Timber Tree for Kenya

The wood of 38-year-old Liquidambar styraciflua grown in a provenance trial plot in Kenya was studied to determine its physical and mechanical properties as well as the relationship between the modulus of rupture (MOR) and static modulus of elasticity (MOE) of the timber. Mechanical properties determined were MOE, MOR, compression strength parallel to grain, shear strength parallel to grain and Janka hardness. Physical properties determined were moisture content and specific gravity. Physical and mechanical properties of small clear specimens from the L. styraciflua were determined according to British Standards (BS 373:1957) using the Universal Strength Testing Machine. The results were analysed using R statistical software (Version 4.4.2). Three trees were sampled, one from each of the three best-performing L. styraciflua provenances, from trials established in 1986 in Lugari Forest Station, Kakamega County, in western Kenya. The sampled trees were from Honduras, Nicaragua and Guatemala provenances. Tree 1 (Honduras provenance) had the highest average strength for all the properties tested. Tree 6 (Guatemala provenance) had the lowest average strength for MOE, compression strength parallel to grain and hardness. Tree 3 (Nicaragua provenance) had the lowest average strength for MOR. Trees 3 and 6 had similar average strength for shear parallel to the grain. Variations in the strength of the three trees may have been due to their different specific gravities. Average strength values for MOE, MOR, compression strength parallel to the grain, shear strength parallel to the grain, and Janka hardness were 12,399 MPa, 106.3 MPa, 52.3 MPa, 16.6 MPa and 5.8 kN, respectively. There was a significant correlation (P<0.05) between the MOR and MOE of L. styraciflua; the correlation coefficient was 0.7. Machine strength grading may be suitable for the Liquidambar timber due to its relatively high correlation coefficient. Liquidambar styraciflua from this study had superior properties compared to those of the current plantation species in Kenya; cypress, pines and eucalyptus. This study therefore recommends L. styraciflua as a suitable tree species for plantation growing for sawn timber in Kenya. In Kenya, L. styraciflua provenance trials were conducted at an altitude of 1,600 m above sea level. Provenance trials in lower altitudes could also be established to determine the growing range of L. styraciflua within Kenya. Further research to determine the physical and mechanical properties of graded structural timber from the species is necessary for design purposes. Additional studies are also required to assess the wood’s susceptibility and resistance to biological agents.