Taxonomic and trophic structure of the biota of agaricoid basidiomycetes in mountain tundras of the Subpolar Urals

The diversity of agaricoid basidiomycetes in mountain tundras of Russia is still underinvestigated. The aim of this work was to identify species diversity and analyze the biota of agaricoid Basidiomycetes in mountain tundras of the Nether-Polar Urals. We collected the material for this article during 2009-2010 and 2012-2015 in the northern part of the western slope of the Subpolar Urals in the national park "Yugyd-Va" (the Komi Republic, Russia, 63°59'N, 59°13'E). The research covered all plant communities and altitudinal belts, presented in the given territory. The studied samples are stored in the Herbarium of the Institute of Biology, Komi Science Centre UB RAS (SYKO). We identified 139 species and intraspecific taxa of the agaricoid basidiomycetes from 35 genera, 17 families and three orders. The leading families are Russulaceae (20.1%), Strophariaceae (15.8%), Inocybaceae (10.8%), Cortinariaceae (10.1%) and Tricholomataceae (8.6%). The leading genera are Lactarius (11.5%), Inocybe (10.8%), Cortinarius (10.1%), Galerina (9.4%) and Russula (8.6%). Comparing with the mountain-forest belt of the Subpolar Urals, in the mountain tundra, the diversity of family Inocybaceae, genera Lactarius, Inocybe, Galerina increases and the diversity of family Tricholomataceae and genus Mycena reduces. The trophic structure of the mycobiota of the mountain tundra of the Subpolar Urals is dominated by mycorrhizal fungi. The share of the mycorrhizal fungi increases from 40% to 50% with the altitude. The share of saprotrophic fungi is 50% of the total species diversity. The saprotrophic on litter dominated among them (27 species, 19%). The group of saprotrophic on bryophytes contains 22 species (15%). Their share markedly increases with the altitude. A high diversity of saprotrophic on bryophytes is typical of the plain tundra. The saprotrophic on humus includes 14 species (10%); their diversity reduces markedly with the altitude. The other groups of fungi (saprotrophic on wood, saprotrophic on leaf, lichenicolous fungi, parasites and saprotrophic on dung) are presented by a small number of species. Agaricoid basidiomycetes are distributed irregularly in the mountain-tundra belt. The greatest diversity is observed in the lower part of the belt. A gradual depletion of the species diversity is observed with the altitude increasing. At the same time, arctic-alpine species appear and prefer dwarf shrub and dryas tundras. Arctic-alpine species, determining the originality and specificity of the mountain tundra of the Subpolar Urals, include 35 species (25% of the total species diversity of the mountain tundra): Amanita nivalis, Cortinarius alpinus, C. durus, C. fennoscandicus, C. minutalis, C. norvegicus, C. polaris, C. septentrionalis, Entoloma alpicola, E. bipelle, Hygrocybe cinerella, Lichenomphalia alpina, L. hudsoniana, Inocybe argenteolutea, I. giacomi, I. salicis-herbaceae, I. subhirsuta, Mycena epipterygia var. badiceps, Galerina arctica, G. pseudomycenopsis, G. pumila var. subalpina, Psilocybe chionophila, Arrhenia lobata, Gymnopus alpinus, Infundibulicybe dryadum, I. lapponica, Lepista multiformis, Leccinum rotundifoliae, Lactarius brunneoviolaceus, L. dryadophilus, L. pseudouvidus, L. salicis-reticulatae, L. torminosulus, Russula nana and R. pascua.

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