The flexural and sawn timber properties of Pinus patula × tecunumanii (low elevation) from the southern Cape, South Africa

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Abstract

Pinus species currently planted for saw log production in the southern Cape, South Africa, present various challenges for growers and processors, including susceptibility to Fusarium circinatum, poor stem form, and various wood quality concerns. In this study P. patula × tecunumanii (low elevation) grown in the southern Cape were evaluated for its suitability as structural sawn timber material. The specific objectives of the study were to determine the flexural and other properties of interest such as the wood density, warp, and the grade recovery of the sawn boards. Sample trees were obtained from two 9-year old Camcore Pinus hybrid trials planted at Kruisfontein and Witelsbos estates. Before harvesting, the diameter at breast height, tree height and the stress wave time-of-flight, using a Fakopp Treesonic, were determined for each tree. The logs were processed into boards of dry dimension 38 × 114 × 3 000 mm. Wood density, bow and spring were measured before destructive testing in bending to determine the modulus of elasticity (MOE) and modulus of rupture (MOR) for each board. The results of this study showed that P. patula × tecunumanii (low elevation) grown in the southern Cape has excellent stiffness properties. Compared to previous research using comparable management regimes (specifically planting density), the only other species planted in South Africa that performed similarly in terms of the mean MOE of sawn boards were P. radiata and P. maximinoi from the southern Cape. The bending strength or MOR was not as good as the MOE, compared to SANS 10163-1 (2003) structural grade requirements, but should be adequate when efficient structural grading is performed. The sawn timber had relatively high and very uniform wood density while the bow and spring (warp) were relatively low. It can be concluded that P. patula × tecunumanii (low elevation) grown in the southern Cape has very good structural timber properties.

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