Discolouration in the Wood of Living and Cut Trees

The various kinds of discolourations in the wood of living and cut trees described in the literature are reviewed and I attempt to classify the different processes involved as physiological, biochemical, and chemical reactions.In a living tree, discolourations are initiated predominantly through wounds and dying branches and roots, where all three types of reactions may be involved.In some species, chemical reactions as e.g. between tannins and metals occur.Discolourations that develop after cu tting of a tree are interpreted mostly as oxydative reactions; however, bacteria mayaiso be involved.Chemical reactions of accessory compounds in contact with metals during wood processing are also discussed.