Inocybe favrei is a widespread but not common arctic-alpine and alpine ectomycorrhizal fungal species associated with dwarf Salix and dwarf birch in snowbed habitats. These habitats have been undergoing climate-driven decline in extent and quality through reduced snow cover, drying, and vegetation shifts (see Threats section for references). Further deterioration is predicted with continued biodiversity loss and decline of specialized alpine mycorrhizal fungal communities under future climatic conditions. Based on these observed and projected habitat trends and the species’ ecological specialization, an ongoing and future global population reduction of at least 15% over a 50-year assessment period is conservatively inferred. The species is therefore assessed as Near Threatened (NT) under Criteria A3c+4c.

= Inocybe decipientoides var. taxocystis J. Favre
= Astrosporina taxocystis J. Favre &E. Horak
= Inocybe taxocystis (J. Favre &E. Horak) Senn-Irlet
= Inocybe taxocystis (J. Favre) Singer

Inocybe favrei and I. taxocystis were synonymized according to phylogenetic and morphological revisions by Larsson, et al. (2018). The species resembles I. rivularis and may be misidentified.

Inocybe favrei is an alpine(-arctic) ectomycorrhizal species connected to Salix herbacea snowbeds and Salix-Betula nana heaths. These habitats are now strongly declining due to climate changes.

Inocybe favrei has a broad geographic distribution in Europe but is likely restricted mainly to the alpine zone and especially to the lower alpine zone. eDNA sequence data from soil suggest that the species also occurs in Greenland, Iceland and North America (Alaska) with a northern distribution in the taiga and boreal forest ecosystems. The species probably has a circumpolar distribution but observational data, is still lacking from many locations.

There are only 195 occurrences in GBIF, a number which definitely is underestimating the actual distribution when comparing with rather well studied alpine areas like Norway with estimated 800 localities. We estimate the total number of known and unknown localities at least 1200 for Northern Europe and a similar number for the Alps and possibly the Carpathian Mountains. We further assume additional at least 1200 localities according to the area of potentially suitable habitat in North America. This adds up to an estimated number of 3600 localities worldwide. We assume on average 5 (10) fungal individuals (unique genotypes) per site each potentially comprising of several clones resulting in a total population size of >20000 mature individuals (cf. Dahlberg and Mueller, 2011).

Trends: Inocybe favrei is easily overlooked, has low detectability, and belongs to a taxonomically difficult species complex, while its alpine and arctic-alpine habitats are also relatively poorly surveyed for fungi. Known records therefore likely represent only a fraction of the true population. It is associated with alpine and arctic-alpine habitats, where suitable habitat have been declining and are expected to continue to decline, particularly due to climate-driven vegetation change. Based on these habitat trends and the species’ ecological specialization, an ongoing global population decline of at least 15% over the next 50 years is conservatively inferred.

This ectomycorrhizal fungus is associated with Betula nana, various Salix shrubs, including S. herbacea and S. reticulata on moist places as close to small brooks and in snow bed areas. The species is known almost exclusively from the alpine zone above timberline, with some arctic records as well.

Inocybe favrei is a widespread but not common arctic-alpine and alpine ectomycorrhizal fungal species associated with dwarf Salix and dwarf birch in snowbed habitats. Although the species is likely substantially under-recorded because of low detectability and taxonomic difficulties, its habitat is undergoing continuing climate-driven change, including reduced snow cover, drying, longer growing seasons, and vegetation shifts that may reduce suitable dwarf-Salix habitat (Björk & Molau 2007; Sandvik & Odland 2014; Matteodo et al. 2016). Predictive studies further indicate continued biodiversity loss and decline of specialized alpine mycorrhizal fungal communities under future climatic conditions (Niittynen et al. 2018; Arraiano-Castilho et al. 2024). Based on these observed and projected habitat trends and the species’ ecological specialization, an ongoing and future global population reduction of at least 15% over a 50-year assessment period is conservatively inferred. The species is therefore assessed as Near Threatened (NT) under Criteria A3c+4c, based on a suspected ongoing and projected population reduction inferred from continuing decline in the extent and quality of suitable habitat.  Inocybe favrei is a widespread but not common arctic-alpine and alpine ectomycorrhizal fungal species associated with dwarf Salix and dwarf birch in snowbed habitats. These habitats have been undergoing climate-driven decline in extent and quality through reduced snow cover, drying, and vegetation shifts (see Threats section for references). Further deterioration is predicted with continued biodiversity loss and decline of specialized alpine mycorrhizal fungal communities under future climatic conditions. Based on these observed and projected habitat trends and the species’ ecological specialization, an ongoing and future global population reduction of at least 15% over a 50-year assessment period is conservatively inferred. The species is therefore assessed as Near Threatened (NT) under Criteria A3c+4c.

Conservation should focus on maintaining the extent, quality, and ecological integrity of known and potential arctic and alpine habitats and preventing avoidable local degradation from infrastructure development, intensive recreation, and other physical disturbance. Although the broader impacts of climate change cannot be addressed through species-specific conservation measures, protecting intact and well-connected alpine habitats may increase the resilience of Inocybe favrei and its host-plant communities to ongoing environmental change.

Inocybe favrei has only relatively recently been synonymized with I. taxocystis and may have been, and continue to be, confused with other members of the I. praetervisa species complex. Because reliable identification of these closely related taxa often requires DNA-based methods, records based on morphology alone may be uncertain. Targeted surveys in suitable habitats and molecular identification of specimens are therefore needed to clarify the species’ distribution, and improve baseline data on population status and trends. Without such data, declines may remain undetected and the severity of current threats difficult to assess.

There is no known significant use or trade of this species.