Species diversity of wood-destroying fungi on Fagus sylvatica L. depending on the structure of dead wood in Western Bulgaria

. During 2022 the stock, value and structure of the dead beech woods (Fagus sylvatica L.) as well as the diversity of the wood-destroying fungi were investigated in four sample areas (SA) situated in Stara Planina Mts. and Vitosha Mt. (Western Bulgaria). The total stock of dead wood in these mountains differs significantly. In SA Petrohan and Barzia (Stara Planina) that amount was 30.04-34.72 m3 ha-1 , but in Tihia kat and Zlatni mostove (Vitosha) 9.93-15.35 m3 ha-1 have been established. The main difference between these two groups of sample areas is the origin of the stand - seed (Stara Planina Mts.) or coppices (Vitosha Mt.). A total of 104 species of fungi were found. The SA Petrohan has the richest species composition (79 species), followed by the SA Tihia kat (29 species), SA Zlatni mostove (24) and the SA Barzia (22 species). The most numerous were the fungi species from the division Basidiomycota (76 species with 254 findings) and the most widespread among them were Stereum hirsutum, Fomes fomentarius, S. rugosum, Trametes hirsuta, Exidiopsis calcea, Trametes versicolor. Among the ascomycetes, 18 species were identified. Their average occurrence is the highest – 8.1 finds per species. The most common were Hypoxylon fragiforme, Xylaria hypoxylon, Diatrype disciformis, Bisporella citrina and Jackrogersella cohaerens. Ten species of the division Myxomycota only were found with average of 1.8 finds per species. The most common was Trichia decipiens, followed by Ceratiomyxa fruticulosa and Physarum sp.