The type of wood decay does not depend on tree species but from several other factors (Read, 2000), among which one of the most important is the kind of fungus involved. There are three main types o wood decay (Kirk & Cowling, 1984; Harmon et al., 1986; Araya, 1993; Read, 2000):

(1) White rot: It produces a whitish or bleached (yellowish or white-greyish) wood, with fibrose texture and balsa wood consistency, in the early stages, and consistency of thick porridge in the advanced stages. Sometimes white rot uniformly affects the wood; in occasions white rot pockets are formed. This rot is produced by basidiomycetes and it is more common in frondose than in conifer trees.

(2) Brown rot (Fig. 1): It produces reddish-brown wood, brittle but stiff and sometimes forming cubes when powdered with the hands; it is more common in conifer trees (Hibbett & Donoghue, 2001) but it also appear in, e.g., chesnuts and oaks. It is produced by basidiomycetes.

Fig. 1. Brown rot in an oak Quercus robur, Stockholm (Photo: Marcos Méndez).

(3) Soft rot: It produces dull-gray to brownigh wood, with a minute check pattern. It only appears in water-soaked wood, so it is more frequen in parts of logs in contact with the soil or in dead wood in aquatic habitats. It if produced by ascomycetes and fungi imperfecti and it is more common in frondose than in conifer trees.

References

Araya, K. 1993. Relationship between the decay types of dead wood and occurrence of lucanide beetles (Coleoptera: Lucanidae). Applied Entomology and Zoology 28: 27-33.

Hibbett, D. S.; Donoghue, M. J. 2001. Analysis of character correlations among wood decay mechanisms, mating systems, and substrate ranges in Homobasidiomycetes. Systematic Biology 50: 215-242.

Harmon, M. E.; Franklin, J. F.; Swanson, F. J.; Sollins, P.; Gregory, S. V.; Lattin, J. D.; Anderson, N. H.; Cline, S. P.; Aumen, N. G.; Sedell, J. R.; Lienkaemper, G. W.; Cromack, K. Jr.; Cummins, K. W. 1986. Ecology of coarse woody debris in temperate ecosystems. Advances in Ecological Research 15: 133-302.

Kirk, T. K.; Cowling, E. B. 1984. Biological decomposition of solid wood. In: Rowell, R. M. (ed.) The chemistry of solid wood: 455-487. American Chemical Society, Washington DC.

Read, H. 2000. Veteran trees: a guide to good management. English Nature, Peterborough.