FUNGAL POPULATION AND COMMUNITY DEVELOPMENT IN CUT BEECH LOGS

Abstract

More than 450 beech (Fagus sylvatica L.) logs, 10 to 20 cm in diameter and 30 to 40 cm long, were cut from freshly felled trees and placed upright 1 m apart with their bases buried up to 10 cm deep in the ground in a plot of about 600 m2 in a mixed deciduous woodland in the Forest of Dean, Gloucestershire, UK. Fungal colonization via the aerial and buried cut surfaces was studied.sbd.in some cases following inoculation of asidiospores.sbd.using a combination of direct and indirect techniques. A wide variety of ascomycetes, basidiomycetes and fungi imperfecti were identified, by direct observation or following direct incubation of wood samples, from the vicinity of the aerial cut surface within the first 6 months after cutting. Some such as Coriolus versicolor (L. ex Fr.) Quel. subsequently increased in occurrence, whereas others, including Chondrostereum purpureum (Fr.) Puz. declined. Isolation onto malt agar from thin sections of wood revealed the presence of some fungi, notably a Fusarium sp., not detected by direct means. In addition, homokaryons on the basidiomycetes Bjerkandera adjusta (Willd, ex Fr.) Karst. and C. versicolor were isolated from near the aerial cut surface up to 2 years after cutting, and, lower down, mostly up until 6 months after cutting (therefore heterokaryons predominated). Moreover, evidence was obtained that small volumes of discoloured, but not strongly decayed wood, sometimes contained large numbers of mutually antagonistic individuals (up to 30 per cm3) of the decay species B. adusta, C. versicolor and Stereum hirsutum (Willd. ex Fr.) S. F. Gray. Vertical penetration from the aeriation cut surface showed a marked lag phase, such that for the first 6 weeks after cutting, overt colonization was restricted to about 3 mm depth. Thereafter the depth occupied increased rapidly.