Wood decay under the microscope

Published Date
November 2007, Vol.21(4):133–170, doi:10.1016/j.fbr.2007.09.001

Revie 

Author 

Francis W.M.R. Schwarze ^a,b,,

aSwiss Federal Laboratories for Materials Testing and Research (EMPA), Wood Laboratory, Lerchenfeldstr. 5, CH-9014 St. Gallen, Switzerland

• bProfessur für Forstbotanik, Albert-Ludwigs-Universität Freiburg, Bertoldstrasse 17, D-79085 Freiburg i.Brsg., Germany

Available online 26 November 2007.

Abstract

Many aspects of the interactions between host wood structure and fungal activity can be revealed by high resolution light microscopy, and this technique has provided much of the information discussed here. A wide range of different types of decay can result from permutations of host species, fungal species and conditions within wood. Within this spectrum, three main types are commonly recognised: brown rot, white rot and soft rot. The present review explores parts of the range of variation that each of these encompasses and emphasizes that degradation modes appear to reflect a co-evolutionary adaptation of decay fungi to different wood species or the lignin composition within more primitive and advanced wood cell types. One objective of this review is to provide evidence that the terms brown rot, white rot and soft rot may not be obsolete, but rigid definitions for fungi that are placed into these categories may be less appropriate than thought previously. Detailed knowledge of decomposition processes does not only aid prognosis of decay development in living trees for hazard assessment but also allows the identification of wood decay fungi that can be used for biotechnology processes in the wood industry. In contrast to bacteria or commercial enzymes, hyphae can completely ramify through solid wood. In this review evidence is provided that wood decay fungi can effectively induce permeability changes in gymnospermous heartwood or can be applied to facilitate the identification of tree rings in diffuse porous wood of angiosperms. The specificity of their enzymes and the mild conditions under which degradation proceeds is partly detrimental for trees, but also make wood decay fungi potentially efficient biotechnological tools.

Keywords

Co-evolutionary adaptation

Host fungus interactions

Light microscopy

Lignin composition

Tree risk assessment

Wood decay

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• ☆
  Dedicated to Alex L. Shigo.

• ∗ 
  Swiss Federal Laboratories for Materials Testing and Research (EMPA), Wood Laboratory, Lerchenfeldstr. 5, CH-9014 St. Gallen, Switzerland. Tel.: +41 71 2747274; fax: +41 71 274 7694.

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