When you sit beside a campfire you can easily feel the energy that is tied up inwoody material. As the wood burns, it is transformed to carbon dioxide, watervapour and minerals – the elements that the tree tied up throughphotosynthesis when it was alive and growing. The combustion of wood in thecampfire takes only a few hours. In temperate and boreal forest ecosystems theequivalent degradation of a tree typically takes 50–100 years and iscarried out by numerous wood decomposers working at a much lowertemperature.

This chapter deals with the activity of these decomposers – how theydegrade and recycle dead wood in forest ecosystems all over the globe. Fungi arethe principal decomposers in terrestrial ecosystems, and especially among thebasidiomycetes we find many effective wood-decaying species. Also a large numberof invertebrates, such as beetles and termites, take part in the process of wooddecomposition. Before we explore this fundamental ecosystem process, we shalldescribe some key aspects of wood structure.

Structural wood components

Wood is made up of three structural components: cellulose, hemicellulose andlignin. The chemical composition, synthesis and degradation of theseeconomically important wood constituents have been important research topics formore than 50 years – and they still are. As a result, we have a goodunderstanding of their biochemical properties. It is beyond the scope of thisbook to go into great detail about these specialized topics, which are regularlyreviewed in books and scientific journals (see Buswell, 1991 ; Markham andBazin, 1991 ; Jeffries, 1994 ; Schwarze et al., 2000b ; Vicuña, 2000 ; Martínez et al., 2005 ; Baldrian, 2008 ).