6 Wood Discoloration

82 3 Physiology
The various competition strategies and reciprocal effects influence the sequence
(succession) of fungi and bacteria that are found at different stages in
the degradation of a complex substrate like wood. Each species uses a different
component of the substrate as it becomes available as a result of the degradation
by the preceding species (Jennings and Lysek 1999). Primary colonists,
bacteria and non-decay fungi (slime fungi, yeasts, molds), rely on relatively
easy assimilable substrates such as simple sugars, starch and proteins and remain
predominantly on the wood surface and within the outer wood parts,
preparing the substrate for following organisms. There may occur a continued
co-existence of non-decay organisms on the substrate. Or the primary colonists
are followed by the decay fungi which are capable of degrading the relatively
refractory wood cell wall components and which penetrate deeper into the
wood such as staining fungi and the brown, soft and white-rot fungi (Levy
1975a; Käärik 1975; Rayner and Boddy 1988).
Schales (1992) found 15 wood-decay fungi on a wind-thrown beech tree
and its stump. Chondrostereum purpureum and Stereum hirsutum occurred
during the initial phase of 2 years. Bjerkandera adusta and Trametes versicolor
were common in the following medium (optimum) phase of 5–7 years.
Kuehneromyces mutabilis and Kretzschmaria deusta were observed in the final
phase (also Jahn 1990; Röhrig 1991). Ten beech stumps showed within 4 years
after tree felling 74 fungal species, 46 Basidiomycetes, 25 Ascomycetes and three
Deuteromycetes (Andersson 1997a; also Willig and Schlechte 1995; Andersson
1997b; Blaschke and Helfer 1999). Those surveys indicate that a substrate is
colonized by more species than commonly described in literature and that
some fungi occur earlier than expected.
While most fungi colonizing wood use nutrients of the substrate, some are
probably only passive occupants using the wood only as a support for fruit
body formation.
Interrelationships between trees and the fungi that inhabit them have been
treated by Rayner (1993).
3.8.2
Mycorrhiza and Lichens
Mycorrhiza (“fungal root”) is the association of mutual benefit (mutualistic interaction)
between a fungus and the root of a higher plant (Agerer et al. to 1986;
Willenborg 1990; Allen 1991; Schwantes 1996; Smith and Read 1997; Varma and
Hock 1999; Egli and Brunner 2002; v.d. Heijden and Sanders 2002; Peterson
et al. 2004). About 80–95% of the higher plants are capable of mycorrhization
(e.g., Bothe and Hildebrandt 2003).
Mycorrhizas are differently grouped. The grouping according to Hock and
Bartunek (1984) in Fig. 3.5 distinguishes three major forms.
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