Abstract
Due to the ongoing climatic changes in the Arctic, the ranges of many plants and animal species are rising higher into the mountains, into the treeline; however, such studies are rare for fungi. The 60-year fruiting dynamics of 66 species of Agaricomycetous macrofungi has been studied along the altitudinal transect located on the slope of Slantsevaya Mountain (Polar Urals, Russia). It has been found that the three basic trophic groups (mycorrhizal, saprobes on litter and soil, and saprobes on wood) fruit higher in the mountains. Additionally, for most of the studied species, a tendency towards upward displacement of fruiting was revealed. The rise in fruiting for saprobes on litter and soil was the most obvious. Mycorrhizal fungi associated with woody plants showed the least uplifting effect. Fungal species that were characterized by fruiting higher up the mountainside half a century ago show stronger upward shifts compared to species previously bearing fruit only at the mountain foot. Probably, such a reaction of the aboveground mycobiota is similar to the processes occurring in the soil, which are associated with an active increase in the decomposition rate of the litter, an increase in the depth of permafrost thawing, and a significant redistribution of the soil water balance. On the other hand, the rise of fungi is associated with an increase of plant biomass in the middle and upper parts, which are the most important sources of fungal nutrition.