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Item Felling induced dynamic stresses in some tropical hardwoods from Nigerian lowland rainforest(2011-06) Omole, A. O.A study was undertaken to estimate the magnitude of dynamic stresses (MDS) induced in some mature tropical hardwood species during felling operation and their effect on the harvested wood. Five areas in Shasha forest reserve, Osun State, Nigeria were selected as the study sites because of the prevalent high. Two hundred and eighty nine trees represented by nine different species were studied. The species are Afzelia africana, Nauclea diderrichii, Terminalia superba, Khaya ivorensis, and Triplochiton scleroxylon Entandrophragma angolensis, Cordia milleniii, Mansonia altissima and Milicia excelsa. Using a checklist, information were collected on tree factors, terrain of the sites and experience of the operators. During felling of each tree, the duration of impact was estimated. Data collected were subjected to statistical analysis. The average content of the green wood ranged from 108% to 147% (dry basis) for all the species. The average impact force ranged from 1.498 X 106N to 7.588 X 106N, while the maximum dynamic stress ranged from 8.38 x 106 N/m2 for Triplochiton scleroxylon (Obeche) to 18.75 x 106N/m2 for Nauclea diderrichii (Opepe). The observed values of dynamic stress are very much higher than the ultimate static stress values for all the species and this will definitely affect the wood quality of the felled trees.Item Damages induced in the woods of some tropical trees during felling(2010-09) Omole, A. O.Merchantable trees in tropical forests are usually widely scattered and the cost of road construction and logging operations are expensive. This calls for finding ways of minimizing felling-induced mechanical damages on wood. This study was carried out to assess and document the magnitude of the incidental damages during the felling of some Nigerian hardwood species in Shasha Forest Reserve in Osun State Nigeria. With utilization potentials and rate of cropping a criteria data were collected with the aid of a checklist on mine species in five different forest stands within the reserve. These include height, diameter, green moisture contents, and estimate of exploitable logs as well as some wood properties. The volume of each tree was computed and the damaged volumes were estimated after felling. Analyses of data were carried out using simple percentages and regression models. Results showed that there are wide variations between and within the studied species with respect of both the tree and wood characteristics. The least average tree height of 40.39m was recorded for Mansonia altissima while the highest average tree height of 56.61m was recorded for Khaya Ivorensis. Merchantable tree volume ranged from 13.68m3 for Mansonia to 46.25m3 for Entandrophragma angolensis while green density ranged from 936.91kg/m3 tp 1845.95kg/m3 and moisture content ranged and 108.09% and 147.05% respectively. Visual assessment of damage volume shows that the degree of damage expressed as a percentage in the studied species ranged between 6.25% and 13.15%. The average damage volume per species is between 7.39% and 12.66% for the selected species. The regression models revealed that the magnitude of the damage portion has significant relationship with tree height, volume and weight.