Decay in Attached Branches

The most detailed studies on fungal community development in standing trees have focused on the sapwood of attached ash and oak branches (Boddy and Rayner, 1983; Boddy et al., 1987). In southern Britain the most common primary colonizers of oak branches were Peniophora quercina, Stereum gausapatum, Vuille-minia comedens, Phellinus ferreus and Phlebia rufa (Boddy and Rayner, 1983). Latent presence has been demonstrated for the first three (Hirst, 1995; Boddy, 2001), but presumably they all have S- and R-selected characters allowing them to exist latently in functional sapwood, and then to develop overtly as mycelia as soon as the high water content/poor aeration regime is alleviated. T. versicolor, P. radiata and Stereum hirsutum were identified as combative secondary colonizers whose establishment depends on conditions having ameliorated sufficiently to allow their growth, and whether they are better combatants under the conditions obtaining. Other secondary colonizers, e.g. Hyphoderma setigerum and H. paradoxa, were less combative but tolerant of desiccation and insect activity. By virtue of this they sometimes replaced both primary and combative secondary colonizers. In the same way Peniophora lycii persisted in terminal branch regions. Analogous communities seem to develop in attached branches of many other deciduous tree species (Butin and Kowalski, 1986; Boddy et al., 1987; Unterseher and Tal, 2006), though the primary colonizers are predominantly Ascomycota in some species, e.g. in Fraxinus (Boddy et al., 1987). The amount of decay occurring in the canopy prior to fall is variable. Complete decay of sapwood can occur in the canopy if it is supported by heartwood, but if not, branches and twigs will fall to the floor, where decay continues.

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