Western redcedar (Thuja plicata) is a high value species in the Canadian forest industry due in large part to the natural durability of its heartwood. Western redcedar heartwood contains extractives that are inhibitory to the growth of many fungi responsible for decay. In order to gain insights into which extractives are important in long term durability, and which fungi are important to decay of western redcedar in service, we conducted a study looking at the fungal community on wood that has been in field tests and monitored for decay for many years. We sampled old growth and second growth western redcedar fence posts that have been in ground contact for 17 years, and deck boards that have been in an above ground test for 14 years. We performed DNA metabarcoding using Illumina sequencing and traditional culturing techniques to characterize the fungal community from samples. Preliminary results from both culture studies and DNA metabarcoding show a predominance of ascomycetes on decks. Basidiomycetes were more frequent on fence posts in the DNA metabarcoding data. The most widespread species detected from decks using DNA metabarcoding was a Hyaloscypha species and from the fence posts was the brown rot species Gloeophyllum sepiarium. The most common species isolated into culture and identified by DNA from the deck samples was the basidiomycete Pachnocybe ferruginea and from the post samples was the zygomycete Mortierella parvispora. Improving our understanding of fungal communities and the role they play in western redcedar decay as well as how they are affected by inhibitory extractives can help in the improvement or development of new wood protection systems, as well as to inform breeding programs aiming to develop seedling stock with enhanced natural durability

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