Climate As A Factor Affecting Distribution Of Wooddecay Fungi

The influence of macroclimatic conditions on current distribution patterns of wood-decay fungi has not been investigated in detail. Thus, it is not known whether gradients of temperature and precipitation are as important to wood-decay fungi as they are to vegetation (Mathiessen and 0kland, 2007). In boreal Scandinavia there seems to be a higher ratio of polypores to corticoid Basidi-omycota in continental sites compared to more Atlantic forests (H0iland and Bendiksen, 1996), which could reflect the polypore sporocarp type being better adapted than the corticoid type to dry conditions. Equally, differences in physiological ecology may be significant. In a comparison of fungal communities on decaying beech (Fagus sylvatica) wood in six European countries there was a close similarity between Sweden and Slovenia, even though these two study areas were the most remote geographically (Heilmann-Clausen, 2005a). The studied regions of Slovenia and Sweden were both characterized by high precipitation (> 1,000 mm/year) and low winter temperatures (mean of coldest month less than —1 °C) which is probably the main explanation for the recorded similarities.

Many polypores causing heart-rot in living deciduous trees have a southern distribution in Europe, for example Ganoderma pfeifferi, Inonotus cuticularis and

Spongipellis delectans (Ryvarden and Gilbertson, 1992, 1993). This could partly reflect the distribution of host trees, but it is noteworthy that these species are often confined to places with a warm microclimate, for example south facing cliffs or grazing forests, in climatically marginal regions, even though host trees show a much wider amplitude in the same landscapes (Martikainen et al., 2000; Heilmann-Clausen, 2005a). Similarly, (Odor et al. (2006), reported that certain threatened polypores and agarics causing heart-rot in beech were more common than expected in Hungarian forest reserves than in Slovenian reserves, probably because of the more continental climate (lower precipitation, larger difference between summer and winter temperatures) in the former, which was assumed to be beneficial for stress-tolerant infection strategies of the species concerned.

Effects of longer term climate changes are now becoming manifest. Most temperate wood-inhabiting fungi produce sporocarps primarily in late summer and autumn, which must reflect mycelial activity, at least to some extent (Chapter 5). Interestingly, over the last 30 years the fruiting season of many species in the U.K. has become extended by earlier first fruiting and later last fruiting, with spring fruiting in some cases, associated with global climate change (Gange et al., 2007; Chapter 5). Similarly there have been reports of wood-decay fungi spreading northwards in Europe, for example Hyphodontia flavipora and Trametes cervina, perhaps as a response to a warmer climate (Keizer and Becker, 2003; HeilmannClausen et al., 2006).

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