Diversity and ecology of macrofungi on large decaying spruce trunks: what has changed after five years?

Macrofungi were monitored on huge decaying Norway spruce (Picea abies) trunks in Boubinsky prales virgin forest in Czechia. The work was done in 2020 on the same trunks and by the same methods as the already published study from 2015. After five years, trunks of decay stage 1 shifted to stage 2, and of stage 2 to 3, whereas no substantial changes were observed on trunks of advanced decay stages 4 and 5. There has been considerable change in cover of bark and mosses. In 2020, higher number of species was recorded. Key role of decay stage followed by bark/moss cover and the total canopy cover for shaping fungal communities was confirmed. The shift in species composition was lowest in trunks of initial decay stages, then slightly increased towards medium stages, and finally decreased in final stage. Species turnover was fastest in the first ten years after tree fall. Consequently, the first survey should be conducted up to 3 years after tree fall and the second one 5-10 years after the fall. Much of the change in species richness and composition was due to different weather patterns in 2015 and 2020. The difference was best explained by the course of mean monthly precipitation. We recommend that field fruitbodies surveys should always be confronted with the course of precipitation and temperature in a given year for assessment of mycodiversity data completeness, while precipitation 1-2 months before mycological inspection is decisive. High conservation value of the locality was highlighted by records of rare old-growth forests fungi, above allDentipratulum bialoviesense.