TEST ASSEMBLIES FOR MONITORING DECAY IN WOOD EXPOSED ABOVE GROUND

No method exists for quantitatively evaluating the durability of wood exposed aboveground. The aim of this study was to develop a test assembly that would (1) be conducive to rapid decay, (2) exhibit minimal variation between replicates in decay response, and (3) lend itself to nondestructive testing in the field. Eighteen different designs for test units of southern pine sapwood were tested in an open field in southern Mississippi in the United States and in a rainforest in Panama. At both locations, test units were exposed above ground to natural infestations of wood decay fungi. No design seemed particularly advantageous in the tropical climate. In the temperate climate, onset of wood decay and frequency of failed units at given intervals of exposure were influenced by the size of the units. Two designs met experimental objectives. Test units of these designs consisted of short lengths of 5.1 cm thick lumber, exposed horizontally, or of stacks of smaller beams that were supported at a 45-degrees angle from the horizontal These designs are being used in additional studies to assess the potential for using nondestructive stress-wave technology to quantitatively measure decay in the field.