Soil yeast communities under the aggressive invasion of Sosnowsky's hogweed (Heracleum sosnowskyi)

The year-round dynamics of the number and taxonomic composition of yeast communities in the soddy-podzolic soils under invasive thickets of Heracleum sosnowskyi were investigated. The yeast groups that are formed in the soil under the continuous Sosnowsky's hogweed thickets significantly differ from the indigenous yeast communities under the adjacent meadows. In the soils of both biotopes, typical eurybiotic yeast species predominate. In the soil under Heracleum sosnowskyi, the share of the ascomycetes Candida vartiovaarae and Wickerhamomyces anomalus is much lower, and the portion of yeast-like fungi with high hydrolytic activity such as Trichosporon moniliforme and Trichosporon porosum is greater. A possible explanation for this phenomenon is that Sosnowsky's hogweed, unlike most aboriginal meadow grasses, does not hibernate with green leaves that do not gradually die out with the formation of semidecomposed plant residues-the main source of nutrients for the soil-litter microbial complex. In addition, grasses of the lower layer do not develop under Sosnowsky's hogweed due to the strong shading and allelopathic impact preventing the development of typical epiphytic copiotrophic species of yeasts.