ECOLOGICAL STRUCTURE OF DOTHIDEOMYCETES IN THE STEPPE ECOSYSTEMS OF THE STEPPE ZONE OF UKRAINE

Abstract

The article considers the ecological structure of the Dothideomycetes and the peculiarities of its formation in conditions of steppe ecosystems of the steppe zone of Ukraine. The materials of the work were the original mycological collecting carried out within the mycological survey of this territory during 2008-2020, sporadic collections of 2021 and 2023, as well as the materials of the herbarium of the M. G. Kholodny Institute of Botany (KW). Herbarium collection and identification of the samples were performed in accordance with the generally accepted methods of cameral processing of xylotrophic, herbotrophic and coprothrophic micromycetes. As a result of our research, characteristic features of the ecological structure of the investigated mycobiota were established. According to the substrate specificity, among the species of Dothideomycetes found in the steppe communities, herbotrophs (74 species) dominate, xylotrophs (28 species), phyllotrophs (14) and coprophiles (7) are also represented. Phytotrophic species of micromycetes develops on 120 species of vascular plants, with the largest number of micromycetes (65 species) noted on plants of the Asteraceae. By trophic specialization, the vast majority of the considered species belong to saprotrophs (103 species), but there are also representatives of pleomorphic hemibiotrophs (20 species). Some hemibiotrophic species at the saprotrophic stage of the life cycle do not have a strict substrate limitation, just like obligate saprotrophs. Species of fungi are discussed. A comparison of the substrate specificity of the studied species of fungi showed that in arid sandy-steppe and sagebrush-steppe plant communities, a wider distribution of herbosaprotrophic species is observed in comparison with meadow-steppe communities. A comparative analysis of the species composition of Dothideomycetes in steppe and forest communities of the steppe zone revealed 13 general species, among which 10 species were found on different plant substrates. The most significant ecological and biological peculiarities of the investigated mycobiota in the conditions of steppe communities of the steppe zone of Ukraine are the formation of stable consortium relationships with a considerable variety of higher plants, zonal and seasonal change of the habitats as a adaptive mechanism for the settlement of the studied species of fungi. The prospect of further research is the study of changes in the species structure of micromycetes under the conditions of anthropogenic influence in the steppe ecosystems of the steppe zone of Ukraine.