Felling Induced Dynamic Stresses In Some Tropical Hardwoods From Nigerian Lowland Rainforest

ABSTRACT

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 millen ii, 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 /08% to /47% (dry basis) for all the

species. T71eaverage ill7,actforce ranged from /.498 X J06N to 7.588 X J06N, while the maximum dynamic stress

ranged from 8.38 x 10 N/m for Trip/ochiton scleroxylon (Obeche) to /8.75 x 106N/m1for Naue/ea 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.