Fungal decomposition of attached angiosperm twigs I. Decay community development in ash, beech and oak

Abstract

SUMMARYInitial stages in the development of fungal decay communities were followed in attached ash {Fraxinus excelsior L.) twigs which had been stressed by girdling and defoliation, and in cut lengths from living twigs of ash, oak (Quercus robur L.) and beech (Fagus sylvatica L.) incubated under controlled drying regimes in the laboratory.Community development in artificially stressed ash twigs was similar to that predicted from previous direct observations. There was direct evidence that most primary colonizers in ash, including Phomopsis platanoidis Died, and Fusarium lateritium Nees., were present as endophytes in the bark of healthy twigs and subsequently colonized wood from this inoculum source. By contrast, secondary invaders were non-endophytic fungi, including Peniophora lycii (Pers.) v. Hohn & Litsch and Libertella fraxinea Oganova. Secondary invaders began to colonize twigs after about 11 months; this was associated with a detectable reduction in moisture content.In healthy ash twigs there was evidence of superficial colonization of woody tissues, lying close to the bark, by endophytes which were not commonly isolated from dead ash twigs, including Aureobasidium pullulans (De Bary) Arnaud and Phoma macrostoma Mont. Superficial colonization was seasonal, reaching a maximum during the winter.A range of endophytes was isolated from healthy oak and beech bark, including Phomopsis spp., Cryptosporiopsis spp., Daldinia sp. and Xylaria spp. Some, but not all, of these endophytes were also isolated from the wood of dead attached oak and beech twigs, and some were able to colonize dying twig lengths under laboratory conditions. Whilst, Daldinia sp. and Xylaria spp. developed in dying twigs of all three tree species in the laboratory, neither were found in decaying twigs in the field. This may reflect different rates of drying in the laboratory and field.

Community structure and dynamics of wood-rotting Basidiomycetes on decomposing conifer trunks in northern Finland

“…As beautifully shown by Rayner, Boddy and their co-workers (Boddy & Rayner 1983c, Coates & Rayner 1985c, Rayner et al 1987, Chapela & Boddy 1988a, b, c, Rayner & Boddy 1988b, Griffith & Boddy 1990, Boddy 1993, wood-inhabiting fungi make up both temporally and spatially changing populations and communities, and the population and community structure and de elopment are based on dynamic interactions of species and individuals (genets). Although the basic biochemical and physiological pathways in wood decomposition, and the general patterns of mycelial dynamics in wood are fairly well known in vitro (Rayner & Boddy 1988a, Eriksson et al 1990, quantitative data on mycelial dynamics, populations and communities is available for just a few species of wood-inhabiting fungi, and most of it for managed forests of the temperate zone.…”

Fungal decomposition of attached angiosperm twigs

“…Although after 6 months small volumes within many lengths had beeti colonized by Phoma macrostoma, Epicocciim nigrum and F. lateriti.u?n, after 12 months the levels of these species in the lengths had declined. Elsewhere it has been observed that P. macrostoma, E. nigrum and F. lateritium superficially colonized living twigs during winter months (Griffith & Boddy, 1990) and, interestingly, in this study the sample of experimental lengths made after 6 months was taken during the winter. These observations may therefore indicate that there is a seasonal invasion of dead attached ash twigs by these species which die back during the summer and return again the following winter.…”

“…12, do not replace each other as they persist in close proximity for a year or more (Griffith & Boddy, 1988, 1990Boddy & Griffith, 1989;Griffith, 1989). The dominant secondary colonizers, Acremonium sp.…”

Fungal decomposition of attached angiosperm twigs

“…However, other factors are also important since, for example, the ascomycete Daldinia concentrica, which is very common in dead attached ash branches, is infrequent in dead twigs, despite the fact that it can grow at xJr less than -4 MPa (Boddy, Gibbon & Grundy, 1985). In this case drying rate appears to be important (Griffith & Boddy, 1990 a).…”