Cortinarius ferrugineifolius is an alpine ectomycorrhizal fungal species associated with dwarf Salix in snowbeds as well as with calcareous Dryas-Salix reticulata heaths. 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.

Cortinarius ferrugineifolius belongs to the hinnuleus group, which in alpine zone is represented by C. ferrugineifolius and C. hinnuleus var. minutalis. These are rather similar, and can be difficult to separate.

Cortinarius ferrugineifolius is an alpine species associated with severely declining habitats (Salix herbacea snowbeds, calcareous Dryas-Salis reticulata heaths).

The species is DNA-sequence-verified from two localities in Norway (Dovre mountains), one in Sweden (Jämtland), one in France (Jura), a few in N Italy (Dolomites), and from Wyoming, W North America from where it was first described.

Cortinarius ferrugineifolius has three DNA-sequence-verified localities in N Europe (Norway and Sweden). Since the species belongs to a difficult group (Hinnulei) with two taxa in alpine zone, and since the alpine habitats are little investigated, known records therefore likely represent only a fraction of the true population. In N Europe, the real/total number of known and unknown localities is estimated to approx 1 000, and with a similar number is estimated for the Alps and the Carpathian Mountains (where it probably also occur). We further assume at least 1 000 localities according to the area of potentially suitable habitat in North America. This adds up to an estimated number of 3 000 localities worldwide. We assume on average 5-10 fungal individuals (unique genets) per site resulting in a total population size of 20 000-30 000 mature individuals (cf. Dahlberg and Mueller, 2011).

Trends: Cortinarius ferrugineifolius is associated with alpine Salix herbacea snowbeds, as well as calcareous Dryas-Salix reticulata heaths. These habitats 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.

The species is recorded exclusively in the alpine zone; both in more or less calcareous Salix herbacea snowbeds, as well as in calcareous Dryas-Salix reticulata heaths.

Cortinarius ferrugineifolius is threatened by climate-driven habitat loss and vegetation change in alpine habitats. Snowbeds, where the species and its dwarf-Salix hosts frequently occur, are particularly sensitive to reduced snow cover, drying, and longer growing seasons, with pronounced vegetation change already documented (Sandvik & Odland 2014; Matteodo et al. 2016; Björk & Molau 2007). Increasing dominance of shrubs and graminoids may reduce suitable habitat for low-growing Salix hosts, while predictive studies indicate that specialized alpine mycorrhizal fungal communities are likely to decline under future climatic conditions (Niittynen et al. 2018; Arraiano-Castilho et al. 2024). Alpine zones are naturally restricted habitats, as populations have limited capacity to track suitable conditions and move upwards. Furthermore, physical disturbance of alpine habitats through construction, e.g. for tourism, negatively affect local populations.

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 Cortinarius ferrugineifolius and its host-plant communities to ongoing environmental change.

Cortinarius ferrugineifolius belongs to complex including two alpine taxa. 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.