Epsilon Open Archive

Abstract

Forests in the northern hemisphere are largely dominated by conifers and provide a key habitat for a multitude of species. Wood decay fungi, i.e. basidiomycetes, are important for nutrient cycling. Saproxylic insects may facilitate the fungal colonization by opening up bark layer, provide a court for introduction, or they can specifically or loosely vector fungal propagules to the substrate.

The aim of the thesis was to clarify the role of insects for dispersal of fungal spores and propagules to Norway spruce stem sections, determine whether mycelial establishment was aided by holes in the bark created by the bark beetle, examine the early succession of fungal diversity in dead wood, and determine whether the hibernation environments for Ips typographus have an impact on the fungal community dispersed by the bark beetle.

Further analysis was conducted on wood material from high stumps and stem sections, mycelia from high stumps, and bark beetles from high stumps, stem sections, standing trees and forest litter. Pure culture isolation, T-RFLP, cloning and 454-sequencing were methods used to explain the fungal community composition.

It was concluded that (i) bark beetles contribute to the establishment of wood decay fungi and act as random vectors; (ii) the fungal community vectored by the bark beetle is depending on the hibernation environment; (iii) beetle entrance and emergence holes on their own have little or no effect on the substrate availability for air-dispersed fungal species; (iv) the fungal community changes drastically in newly created dead wood and the ecological interaction between fungi and dead wood is complex; and (v) the complexity of the fungal community detected is influenced by the method used to analyze it.

Overall, bark beetles have a major impact on fungal dispersal and colonization success of wood-decay fungi.