Fungal colonization patterns of wood exposed out of soil contact in Western Oregon

Abstract

Wood is among the most decay-resistant cellulosic materials; however, all organics eventually succumb to decay. Understanding the degradation process is important when considering how products perform, but this knowledge can also be useful when determining how climates affect the organisms involved and the rates at which degradation occurs. Above ground wood decay tends to occur more slowly than decay in direct soil contact and is more dependent on climatic differences and wood species chemistries. While above ground wood deterioration is a subject of interest, most research has concentrated on the effects of the organisms on the wood. There are surprisingly few comprehensive studies of the fungi involved in the process and most have been performed under aggressive tropical conditions. Fungal colonization of red alder and Douglas-fir samples exposed above ground was evaluated over a 24-month period. Red alder is highly susceptible to fungal attack while Douglas-fir is moderately resistant. As such, they presented two differing selective media for fungal colonization. Red alder was more heavily colonized than Douglas-fir, reflecting the differing susceptibility of the two wood species to degradation. A similar number of Ascomycete and Basidiomycete species were isolated (11 vs 8 species, respectively), but Basidiomycetes were more frequently isolated. These results were similar to those found under more tropical conditions. The results illustrate the wide range of species that colonize wood exposed above ground.