Physical, Anatomical and treatment Characteristics of the Wood of Cola Gigantea and Ficus Sur

A nation – wide market survey study discovered that more than 47 timber species are being sold on Ghanaian market whose technological properties are not known. Therefore to ensure efficient utilization and promotion of these timber resources, their technological properties must be determined. Two species namely Cola gigantea and Ficus sur were selected to determine their technological properties. This study focused on the green and air – dried moisture contents, basic density, anatomical properties and the treatment characteristics of Cola gigantea and Ficus sur from Pra – Anum Forest Reserve in the Moist Semi Deciduous Forest Zone of Ghana. The green and air – dried moisture contents were determined using ASTM D4442 – 07; basic density of the species was done using the immersion method ASTM D2395 – 07a and the anatomical description using IAWA committee, 1989 protocols. The treatability studies was conducted using 0.5 % Copper Chrome Arsenate type C (CCA – C) preservative AWPA P5 – 08 and vacuum-pressure impregnation method by varying the pressure magnitudes (600 kPa to 1200 kPa) and treatment durations (30 to 240 minutes). The depth of penetration was done by AWPA A3 - 08, the assessment of permeability of the wood species by Fougerousse, 1976 method and preservative oxide retentions by AWPA A9 - 01. The heartwood of C. gigantea has significantly higher green moisture than its sapwood at P<0.05. There was no significant difference in green moisture content between the sapwood and heartwood of F. sur at P≥0.05. Green moisture content varied along the bole of both species. Air – dried moisture content varied slightly within and between species but the differences was not significant. Mean basic densities were 479 kg/m3 for Cola gigantea and 386 kg/m3 for F. sur. The mean basic density values for sapwood of both species were significantly different at P< 0.05 from their respective heartwood. The mean basic densities varied from the butt to the top portions of both species. The ground tissue proportions namely vessels: parenchyma: fibres were 8 %: 43 %: 49 % for C. gigantea and 59 %: 47 %: 44 % for F. sur. The fibre length, lumen diameter and double wall thickness were 2.0 mm, 14.8 μm and 9.9 μm for C. gigantea and 1.5 mm, 23.9 μm 7.5 μm for F. sur. There was no significance between sapwood and heartwood volumetric retention of both species. F. sur significantly has higher volumetric retention than C. gigantea at P≤ 0.05. The ratio of mean longitudinal to transverse penetrations was about 32 to 1 for C. gigantea sapwood and 39 to 1 for its heartwood and those of Ficus sur sapwood and its heartwood were 22 to 1 and 24 to 1 respectively. The ratio of longitudinal to transverse penetrations was 36 to 1 for Cola gigantea and 23 to 1 for Ficus sur. The sapwood of F. sur and heartwood of both species were rated as moderately resistant when treated at 1200 kPa for 30 minutes or more whilst the sapwood of C.gigantea was rated as moderately resistant when treated at 1200 kPa for at least 60 minutes. The heartwood of both species is relatively more permeable than their respective sapwoods. For the same range of pressure magnitude and duration as well as 0.5 % CCA-C oncentration used in this study, the mean oxide retention of Cola gigantea sapwood ranges were 1.41 to 2.21 kg/m3 and its heartwood were 1.39 to 2.29 kg/m3 and those of Ficus sur sapwood were 1.86 to 3.21 kg/m3 and 1.89 to 3.19 kg/m3 for its heartwood. Ficus sur can also be used as substitute for Triplochiton scleroxylon (wawa), Pycnanthus angolensis (otie) and Antiaris toxicaria (kyenkyen). Both species are treatable and therefore can be impregnated with adequate amount of preservative to prolong their service life.

Source: KNUST