Assessment Notes

Justification

Amanita friabilis is a small ectomycorrhizal fungal species that associates exclusively with Alnus spp. in wet to temporarily flooded habitats in Europe and Asia, mainly in the boreal, continental and alpine regions. The species is reported to have been declining in several countries. Its hosts, in the genus Alnus, have been undergoing deterioration across Europe due to disease (e.g. Phytophtora alni). The conservation status of its most common habitat has been reported as “unfavourable-bad” in the same regions where Amanita friabilis mainly occurs, meaning the habitat is in serious risk of becoming regionally extinct. The past and ongoing decline of the hosts is inferred to directly affect the population size of the species. The total number of mature individuals is suspected not to exceed 20,000, and the number of mature individual at each locality is typically less than 50, with no subpopulation containing more than 100 mature individuals. Therefore, the species is assessed as Near Threatened (NT).

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Taxonomic notes

There are cryptic species in Amanita friabilis sensu lato at the global scale (Ainsworth and Suz 2018). However, for the purpose of this assessment, we treat it as a single taxon.

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Geographic range

Amanita friabilis is widespread in Europe, but occurring mainly in boreal, continental, and alpine regions. It is also reported in Türkiye, in western Siberia (a few records), Altai and the western Caucasus. It can be considered rare in the Mediterranean region, with the largest subpopulations found further north in Finland, Germany and Sweden (Lüderitz and Gminder 2014).

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Population and Trends

The species mainly occurs in the boreal, continental and alpine regions. It is rarer in the Atlantic region and very rare in the Mediterranean region. According to Fraiture and Otto (2015), the number of known sites in Europe was about 100. Outside Europe, it is extremely rare, (e.g. one single record in western Siberia).

The most common habitat of Amanita friabilis is "Alluvial forests with Alnus glutinosa and Fraxinus excelsior" (Natura 2000 code 91E0). According to the report under Article 17 of the EU Habitats Directive (European Environmental Agency 2012), the conservation status of this habitat is “unfavourable-inadequate” in Black Sea, Mediterranean and Pannonian (Carpathian) regions and “unfavourable-bad” in the Alpine, Atlantic, Boreal, and Continental regions, meaning the habitat is in serious risk of becoming extinct (at least regionally) (Evans and Arvela 2011), in the regions where Amanita friabilis mainly occurs. The habitat is assessed as declining in all regions except the Black Sea and Continental (stable) and Mediterranean (unknown) regions (European Environmental Agency 2012).

Populations of Alnus, the exclusive host of Amanita friabilis, have been deteriorating as a result of pest damage and disease. The oomycete pathogen Phytophtora alni is now reported in ten European countries posing a serious threat to Alnus glutinosa; note that trees growing on riverbanks or flood plains are particularly vulnerable since the presence of water appears to facilitate the transport of the pathogen (Durrant et al. 2016). In another example, 'Alnus viridis' (=Alnus alnobetula; Govaerts 2013) in the Alps is declining due the fungal pathogen Valsa oxystoma (Mauri and Caudullo 2016). According to Lüderitz and Gminder (2014), Amanita friabilis and its Alnus swamp/alluvial forest types are also endangered due to forestry, drainage/lowering of groundwater table, eutrophication/N-enrichment, influence from roads/settlements and other disturbances.

Because Amanita friabilis is exclusively associates with alder species, the past and ongoing decline of the hosts is inferred to directly affect the population size of the species. The total number of mature individuals is suspected not to exceed 20,000 due to a suspected total number of localities to be less than 700 with an average of 3 genetically unique mycelia (corresponding to 30 mature individuals) per locality (cf. Dahlberg and Mueller 2011).

The species is considered Extinct in The Netherlands and is Red Listed in several European countries: e.g. Austria (EN), Czech Republic (EN), Estonia (VU), Sweden (NT).

Population Trend: Decreasing

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Habitat and Ecology

According to e.g. Lüderitz and Gminder (2014), Amanita friabilis is strictly associated with Alnus spp. and is ectomycorrhizal. The species occurs with Alnus glutinosa, Alnus incana and in the Alps also with 'Alnus viridis' (=Alnus alnobetula; Govaerts 2013), and in Altay with Alnus alnobetula subsp. fruticosa. In northern Europe the species occurs mainly with Alnus incana, and in the lowlands of central Europe more frequently with Alnus glutinosa. The species occur normally in wet forests, often in flooded parts along the rivers. It is restricted to wet soils and tolerates temporary flooding. In Fennoscandia, it also occurs in naturally established alder groves along water courses in abandoned farmlands. The species occurs in the following NATURA 2000 habitats (codes): 6310, 9010, 9050, 9080, 91E0. Alluvial forests with Alnus glutinosa and Fraxinus excelsior (91E0) is the most common habitat.

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Threats

Forest management and invasive alien fungal pathogen species affecting the hosts are major threats. Lüderitz and Gminder (2014), highlight threats to the species and its habitats as coming from forestry, drainage/lowering of groundwater table, eutrophication/N-enrichment, influence from roads/settlements and other disturbances.

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Conservation Actions

European member states indicated four conservation actions: Establish protected areas/sites, adapt forest management, restoring/improving forest habitats, and restoring/improving the hydrological regime. Further research into the distribution, trends, taxonomy and ecology of the species may also be beneficial.

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Use and Trade

The species is not known to be used.

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Source and Citation

Gonçalves, S.C. 2023. Amanita friabilis. The IUCN Red List of Threatened Species 2023: e.T125433712A125435490. Accessed on 22 November 2025.

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• Country occurrence