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Dead wood in the forest - alive and dynamic!
Authors: P. K. Buchanan, P. W. Clinton, R. B. AllenPublication: New Zealand Journal of Forestry, Volume N.Z.J.For. 2000, Issue N.Z.J.For. 45(4) 2001, pp 40-42, Jan 2001
Publisher: New Zealand Institute of Forestry
Abstract: The study discusses the role of fungi in decomposition of wood, focusing on New Zealand beech (Nothofagus) forest. An estimated 22 000 species of fungi are thought to occur in the country, based on ratios of fungi to plants from regions where constituents of both groups are well known. In New Zealand beech forests, the mycorrhizal fungi are mainly ectomycorrhizal Basidiomycetes that form mushrooms and mushroom-like sporocarps. Two main enzymatic systems gives rise to the two main kinds of wood rots: white rot (in which the cellulose, hemicellulose and lignin are degraded) and brown rot (in which cellulose and hemicelluloses are degraded to leave a residue of brown lignin). Two other types of decay are also typical of the decomposition process but are less significant: non-wood decay and soft rot. To gain a preliminary understanding of rates of decomposition, test blocks of wood of three Nothofagus species were inoculated with 12 beech-inhabiting fungi. Decomposition rates under experimental conditions seem to reflect the ecological role of the fungi, e.g. the most vigorous decomposer (Coriolus versicolor) is an early colonizer of fallen beech and can be seen among the first fungi to fruit in open sites. On the other hand, Australoporus tasmanicus is most commonly seen on well-decayed logs and may colonize the substrate only after decomposition by other fungi. Sporocarp N concentrations ranged from 12-55 mg/g, while logs contained 1.5 mg/g N and the forest floor 8.7 mg/g. These results suggest that the decomposition process requires interaction between a broad range of fungal species.