The community of soil fungi associated with the western red cedar (Thuja plicata Donn ex D. Don, 1824)

The western red cedar (Thuja plicata Donn ex D. Don), an important forest-forming species in the Western part of the North American continent, is an alien species naturalised in Europe. It is popular and highly valued in horticulture. While considering the progressing climate change, it may also be a potential alternative to native species in European forests. The community of soil fungi associated with the western red cedar in forested areas of Europe has not been fully determined. Thus, this study is aimed to identify the community of soil fungi associated with the western red cedar. The experimental plots are located in the Kościan Forest District (51°98’87″ N; 16°23’54″ E). All soil samples were taken from the topsoil layer at a depth of 25 cm with a trowel, three from the centre of natural regeneration (1G, 2G, 5G) and three from the centre stand under the canopy of old-growth western red cedar (3G, 4G, 6G). Fungi were identified directly from the soil based on the ITS1 rDNA region. The derived product was sequenced using Illumina’s sequencing by synthesis (SBS) technology. Sequences were referred to the National Center for Biotechnology Information (NCBI) database applying the BLAST algorithm. The fungal counts were defined based on the number of operational taxonomic units (OTU) in the sample. The OTU number was 835 206, with fungal isolates accounting for 683 095 (81.79%). A total of 8 591 taxa belonging to the Kingdom Fungi were identified. The species with the greatest shares in the community included Mortierella spp. (10.5%), Russula spp. (5.6%), Hydnum spp. (3.44%), Solicoccozyma spp. (3.1%) and Penicillium spp. (2.2%). Results showed that saprotrophs and mycorrhizal fungi predominated in the community. The dominance of ectomycorrhizal fungi over arbuscular ones, quite impressive natural regeneration was shown in T. plicata stands in Kościan. Subsequent research should take into account tree stands in Poland in which natural regeneration does not occur or occurs sporadically.