Pinus patula is one of the major exotic species grown in Malawi mainly for saw-timber production. It is native to Mexico. Little has been reported about the mechanical properties of the wood. The objective of this study was to investigate the mechanical properties of Pinus patula in more detail, in order to provide a basis for utilizing this resource. The mechanical properties of small clear wood specimens of Pinus patula were evaluated using 40 cm logs from 1, 3, 5, 7 and 9 m above the ground. Small clear wood specimens were selected and subjected to a bending test in accordance with Japan Industrial Standards (JIS) air-dry conditions. The growth rate did not affect the mechanical properties measured. There were significant correlations at 1% level between air-dry density and Modulus Of Elasticity (MOE) (R = 0.85) and between air-dry density and Modulus Of Rupture (MOR) (R = 0.83). There was also a significant correlation between MOE and MOR at 1% level (R = 0.90). At about 12% moisture content, the tested five Pinus patula families have average MOR and MOE of 105.17 MPa and 10.93 GPa, respectively.
Growth ring structure and wood density were compared among five families of Pinus patula planted in Malawi, Africa. The vertical and radial variations of wood density and growth characteristics were investigated in stems of 30-year-old Pinus patula planted at a spacing of 2.74 × 2.74 m. The pattern of ring width with cambial aging was broadly similar at all stem heights: wide to the 4 th growth ring, decreasing gradually up to the 10 th ring and then very narrow towards the bark. In all the families, the first complete growth ring was the widest, ranging from 20 to 50 mm across the families. This trend was different from other similar studies carried out in Zimbabwe and South Africa where the growth ring width increased from the 1 st to the 3 rd ring with the highest ring width of 19 mm. Specific gravity varied with height above the ground for all the trees. The average specific gravity was 0.56. Weak to medium correlations between latewood percentage and specific gravity were observed. The study shows that selection for density in Pinus patula could be made at least by the age of 10 years.
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