ABSTRACT

The study examined some wood pulp properties of Pinus caribaeafmorelet) grown in Oluwa forest reserve ( a world bank assisted pulpwood project) in Ondo State, Western Nigeria. The study determined the extent to which the variation in wood density of Pinus caribaea (morelet) was associated with differences between plantations, between trees and within trees, investigate the relative suitability of the wood species based on density and other wood properties for pulp and paper making, determine the relationship, if any, between wood density and shrinkage variations and determine the effects of ring width on wood density and wood type. Wood samples were collected from different age classes and each age class was a 25 hectare plantation. The ages were 15, 16, 17, and 18 years, established in 1989, 1990, 1991, and 1992 respectively. Three (3) well formed trees were randomly selected from each plantation. Diameter at breast height and the 4 cardinals were marked before the trees were felled. A total of sixty (60) discs of 50 millimetres (mm) in thickness were collected at 5 sampling levels of 10%, 30%, 50%, 70% and 90% of merchantable length from the 4 plantations. Strips of 20mmx20mmx20mm were obtained when each disc was sawn radially from the bark to the pith and partitioned into inner wood (A), middle wood (B), and outer wood(C) based on the number of annual rings counted from the pith to the bark. Data obtained were analyzed using graphs, analyses of variance, correlation and regression. Differences in wood density, shrinkage and ring width due to age, level and tree were highly significant. Mean values for wood density were 0.52g/cm3,0.47g/cm ,0.43g/cm3 and 0.36g/cm3 for 15, 16, 17, and 18 years old plantations respectively. Wood density increased with decreasing age. Variance components from the age classes were 30.9%, 27.6%, 25.1% and 27.5% in respective ages. Wood density variation axially did not follow any patter in all the 4 plantations. Ring width variation along the bole did not follow any pattern in 15 and 16 years old plantation. In 17 and 18 years old plantation, ring with increased with decreasing ring number with mean values of between 1.6% and 2.4%. However, a strong correlation existed between sampled levels in all the plantations. The pattern of volumetric shrinkage showed an increase with increasing level with mean values that lay between 7.2% and 12.5% with a prediction of 74.5%. The effect ofwood type on the total variation in volumetric shrinkage was significant with mean values of between 6.1% and 17.4% with a high prediction level of 80.5%. The pattern of variation in tangential shrinkage was an increase from the pith to the bark and mean values that lay between 2.7% and 8.2% were obtained. The highest aggregate mean value in tangential shrinkage was obtained at 90% merchantable length with values between 2.8% and 7.2% in all the plantations. This study did not obtain any specific pattern of variation in radial shrinkage along the tree bole in all the 4 plantations. However, results gave a mean average radial shrinkage that lay between 3.05 and 7.0%. The results of this study have shown that the wood density of the species was within the acceptable minimum (0.30g/cm3) and maximum (0.80g/cm3) range recommended for pulp and paper manufacture. Pulp yield was closely related to wood density and this research gave a minimum of 0.36g/cm3 from 18 years old plot while the 15 years old plot gave 0.52g/cm3.this study recommended among other things that the plantation should be harvested without undue delay since wood density dropped with increasing age.