A new method for evaluating decay: the effect of oxygen on Polyporuscompactus in red oak

Abstract

The effects of oxygen decay (weight loss) incited by Polyporuscompactus Overh. was studied using small fresh and dried wood blocks containing both sapwood and heartwood of similar radial position and age. A manifold was used to deliver hydrated gas mixtures of 1.0, 4.2, or 21% (ambient air) oxygen at constant pressure and continuous flow to jars containing inoculated or noninoculated blocks. Means (P = 0.05) for dry weight losses in inoculated blocks at 1.0, 4.2, and 21% oxygen were 3.3, 8.9, and 21.4%, respectively; losses may be comparable to decay by other white rot fungi using the soil-block procedure. Losses in noninoculated blocks at the above oxygen levels were 2.0, 4.6, and 7.0%, respectively. Differences in dry weight losses between fresh and dry blocks were found. In particular, losses in inoculated fresh blocks were significantly less than losses in inoculated dry blocks in ambient air. Native inhabitants occurring in fresh wood appear to interfere with the decay processes of P. compactus. Losses in noninoculated fresh blocks were significantly greater than in noninoculated dry blocks at 21% oxygen but not at 1.0 or 4.2% oxygen; losses were attributed to natural inhabitants in fresh wood.