Do traits explain colonization-extinction rates of wood-decaying fungi?

Abstract

In Fennoscandia, intensive forest use has led to substantial decreases in the amount and diversity of dead wood, which constitutes critical habitat for saproxylic species such as wood-decaying fungi. The transient nature of the dead wood habitat implies that metapopulation persistence of wood-decaying fungi depends on the continual colonization of newly created habitat. Dead wood dynamics in turn are strongly influenced by forest management practices. Very little is known about the dispersal ecology of most species and there are competing hypotheses about functional trait effects on dispersal and colonization rates as well as on species sensitivities to forest management.

We test for the effects of traits on colonization and extinction rates using hierarchical modelling of 79 species of wood-decaying polyporoid fungi. We use data from an extensive survey in Finland of 258 forest stands of differing stand type that were surveyed twice at an interval of on average 13 years. Functional relationships between fungal morphology and rates of dispersal, establishment and development of fruiting bodies are an area of active research. We therefore broadly test for effects of spore traits (spore size, spore shape, and spore cell wall thickness; hypothesized to affect dispersal and germination probability) and traits describing the hyphae and fruiting body (hyphal system type, fruit body type, size and lifespan; hypothesized to relate to growth rate, competitive ability and longevity) on colonization and extinction rates.

Results will be informative regarding traits and mechanisms that mediate colonization-extinction dynamics as well as sensitivities to forest management of wood-decaying fungi. A better understanding of the ecology of this important functional group is imperative to improve conservation measures aimed at halting these species' decline.