Diversity of wood-inhabiting fungi in woodpecker nest cavities in southern Poland

Robert Jankowiak,Michał Ciach,Riikka Linnakoski,Piotr Bilański

doi:10.5586/am.1126

Abstract

Globally, tree-holes are important ecological component of forest and woodlands. Numerous microorganisms rely on cavities, both natural and those excavated by primary cavity nesting birds, mainly by woodpeckers, for their survival and reproduction. However, the fungi occurring in cavities are not well characterized. Specifically, very little is known about the fungal communities inhabiting the woodpecker nest cavities. Therefore, in this study, we investigated the fungal diversity of cavities in southern Poland. The samples were collected from freshly excavated woodpecker nest cavities using a nondestructive method (ND). The spatial distribution of fungal communities within the cavities was evaluated by sampling different parts of a single cavity using a destructive method (D). We detected 598 fungal isolates that included 64 species in three phyla and 16 orders using the ND method. Most of the fungi isolated from the cavities represented the phylum Ascomycota (73.9% of the isolates) with 11 orders, and Microascales was the predominant order (30% of the isolates). The most common species detected was <em>Petriella musispora</em>, which was isolated from 65% of the cavities. A total of 150 isolates (25%) were members of Basidiomycota, with Hymenochaetales being the dominant order (16% of the isolates). The basidiomycetous fungi were isolated from 55% of the cavities. Several taxa closely related to the pathogenic fungi and associated with secondary animal infections were detected in the wood of cavities. We identified different fungal communities in the three cavity parts using the D method. The cavity entrance had more number of species than the middle and bottom parts. The results of this study advanced our current knowledge on the mycobiota in woodpecker nest cavities and provided preliminary evidence for tree cavities being the hotspot for fungal diversity.

Highlights

Tree-holes are important ecological component of forest and woodlands
As the initial morphological survey of the isolated cultures and internal transcribed spacer (ITS) sequence data revealed that our morphotypic criteria were not stringent, the morphotypes were grouped into 69 species based on the ITS and other gene sequence analysis
The ITS and large ribosomal subunit (LSU) sequence analyses within the order Microascales revealed that 43 isolates resided in two major phylogenetic clades: Graphiaceae and Microascaceae (Fig. 1 and Fig. 2)

Summary

Introduction

Tree-holes are important ecological component of forest and woodlands. Tree-holes are formed by three major mechanisms: natural formation, where the fungi decompose the wood over time; excavation by birds, mainly by woodpeckers, which are often considered as habitat engineers that play a key role in forest ecosystems [1]; Published by Polish Botanical SocietyJankowiak et al / Fungi associated with woodpecker nest cavities in Poland wood-boring insects that attack and damage the bark and wood of trees [2]. Especially the wood-decay species, can assist avian species to excavate cavities in the stems and branches of trees by softening the wood [5,6,7,8]. Most Holarctic woodpecker species are reported to select trees that are softened by fungi, including the sections of tree bole that contain heart rot for cavity construction [6,7,9,10]. The trees selected for cavity excavation by woodpeckers may be inhabited either by specific fungal species [11] or by distinct host fungal communities [8,12]. Red-cockaded woodpecker (Picoides borealis) prefers trees infected with the heart rot fungus, Porodaedalea pini for cavity excavation [6,8]. Jusino et al [13] reported that Picoides borealis shares a symbiotic relationship with the fungi, where the fungi may help excavators by softening the wood and the excavators may facilitate the fungal dispersal

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Conclusion