R-L categories correct, but text here does not match final assessment. Developed and updated version published at IUCN´s Red List update, July 18th 2019.
Cortinarius atrovirens is phylogenetically very similar to C. ionochlorus (w/ e.g. identical ITS sequences). However, morphologically and eco-geographically these are clearly dissimilar, and should be treated as different taxa, either subspecies (C. atrovirens ssp. atrovirens and ssp. ionochlorus) or species. For practical reasons, we treat these as species in the present redlist assessment.
Cortinarius atrovirens is a mycorrhizal species associated with Abies alba and rarely with Pinus sylvestris and Fagus sylvatica. It is one of the more characteristic and well-known species of the rich fungus element of the (mixed) calcareous montane Abies alba forests of C and S Europe. These habitat specific species suffer from rthe fragmentation and decline of the small calcareous fir forests of e.g. Black Forest,the Jura, Prealps and Carpathians.due to areal loss and and influence from modern forestry, including introcuction of Picea plantations.
The decline of the habitat-specific fungi of the calcareous Abies forest element is due to a long-term and persistent decline in mature/old silver fir forests, due to forestry. For instance the montane mixed Abies forests of the Prealps, where these species has a main area, has had an increased forestry activity, with a doubling of annual felling the last 40 years, according to forestry statistics (Austria), and these are now listed as endangered habitats in the habitat red-list of Austria. In the same period, we have seen a shift from Abies stands to planting of Picea in many hotspot regions of Cortinarius atrovirens and allies. Furthermore, a habitat-loss is probably seen in many silver fir regions due to settlement/tourist resort expansion, road construction, ski tracks, etc. The narrow bands of Abies forests in the Alp valleys may also be vulnerable to climate change, including pathogen outbreaks. The mature, often grazed calcareous pine forests with Cortinarius atrovirens at Gotland, Sweden is also declining, due to forestry and the expansion of limestone quarries, as well as altered management practices with the loss of cattle grazing.
Cortinarius atrovirens has a limited European distribution. It is rare to very rare, but locally more frequent in calcareous regions (The Jura, Black Forest, Gotland), sometimes forming large rows or fairy rings. More or less restricted to the natural Abies alba distribution area; S Germany (Krieglsteiner, 1991; Garnweidner & Ott, 1991), Poland (Nespiak, 1975), Switzerland and Austria (Senn-Irlet et al., 2003; Breitenbach & Kränzlin, 2000; Engel & Friederichsen, 1971, 1974), France (Henry, 1939; Chevassut, 1991) including The Pyrenees (Mahiques, 1999), Italy (Consiglio et al., 2004), Yugoslavia (Moser, 1961) and Hungary (Kalchbrenner, 1873-1877). In E France up to 1500m. a.s.l. (Marchand, 1983). Recorded outside the natural Abies range on the limestone islands of the Baltic Sea (Gotland and Öland, SE Sweden, Larsson, 1997 and Saaremaa, NW Estonia: , Jeppson, 1993), in W Ireland (Burren, Harrington, 1996), in NE England (Scarborough, Cooke, 1886-1888; apparently not recollected in recent decennia, cf. Orton, 1955) and in parts of Italy (Consiglio et al., 2004). Not reported from the calcareous Abies nordmanniana forest of Caucasus-N Turkey, and not reported outside Europe.
At least in some regions, the species is not infrequent in Phlegmacium-rich, calcareous Abies forests. Approx 100 localities are indicated from national databases and literature (mainly from Germany, Austria and Sweden). The real/total number of sites/localities are estimated to approx 1000 in Europe (=global population), corresponding with a total of approx 20 000 individuals.
According to sites seen and to literature, the species is mainly associated with older Abies(-Picea) stands, without influence of modern forestry with clear-cuts. At Gotland (Sweden) the species is associated with older, grazed Pinus forests. These forest types are now declining, the old Abies forests due to forestry including Picea plantations, and areal loss due to mainly to settlement/tourist resort expansion, etc, now being regarded as a vulnerable forest type in the Prealp region. Inferred from this habitat trend, it is probable that also the populations of C. atrovirens are declining, at the same rate as the habitat. The Gotland populations are furthermore lost due to expansiaon of lime quarries (see Introduction/Justification).
The decline in Central-South European old-growth, calcareous Abies or mixed Abies-Picea forests due to forestry and and habitat-loss is estimated to to approx (10-)15-20% during the evaluation period. Based on this, the species becomes red-listed as NT (“close to VU”) according to the A criterion (A2c + 3c + 4c). The species is furthermore probably to be red-listed as NT (“close to VU”) according to the C-criterion based on continuously decline, combined with an estimated population size of <20 000 individuals, and very small subpopulations.
Population Trend: Decreasing
The species is a mycorrhizal associate mainly with Abies alba, sometimes also with Pinus sylvestris (especially outside the natural distribution of Abies alba), sometimes apparently also with Fagus sylvatica. The species is a typical member of the Cortinarius subgenus Phlegmacium element more or less restricted to the calcareous, mossy Abies alba or mixed Abies-Picea-Fagus of montane Central Europe (including the Appennines). Here the species occurs in typical hotspot sites with many other phlegmacia, such as C. haasii, C. odorifer, C. russeoides. According to own observations and literature from e.g. Black Forest and the Austrian Eastern Prealps, the species mainly occurs in older/old-growth Abies forests. In a few northern outpost, probably of relictual nature (mainly Gotland), the species occur in calcareous Pinus forests, and in southwestern outposts in Spain, the species also is reported in Pinus forests.
Cortinarius atrovirens is threatened by habitat-loss and reduced/depauperated habitat conditions. Its major habitat; older calcareous Abies alba forests or calcareous mixed Abies-Picea abies is apparently declining in entire central Europe. The decline is documented e.g. in Austria where montane basiphilous Abies-Picea forest are regarded as endangered habitats, vulnerable e.g. to forestry, with a doubling of annual felling last 40 years, according to forestry statistics (Austria). Furthermore, according to own observations, a number of Abies stand become planted with Picea abies after clear-cutting. Furthermore, habitat-loss due to road construction, settlements including tourist resort expansion are seen in many areas. The narrow bands of Abies forests in the Alp valleys may also be vulnerable to climate change and pest outbreaks. The calcareous Pinus sylvestris forests with Cortinarius atrovirens at Gotland, Sweden, are also declining, due mainly to lime quarry expansion and altered management practices, with the loss of cattle grazing.
To prevent decline and fragmentation of calcareous Abies-Picea-Pinus forests with good habitat quality, it is important to set aside reserves on calcareous hotspots, i.e. in sites housing many rare/redlisted species such as C. atrovirens, C. citrinoolivaceus and C. haasii. It is furthermore important to establish woodland key biotopes or equivalent management regimes, where only a non-intensive, closed cutting is allowed, leaving much of the stand qualities intact, including a continuity of the fir (or pine) roots and their mycorrhizae.
More research is needed to find out how much of extensive forestry (selective cutting) the species can manage, and to what degree the species re-establish in young (planted) forests after clear-cutting. More mapping is needed, especially in eastern-southeastern parts of the distributional range of Abies alba (the eastern Carphathians and the montane Balkans).
Genetic studies with more molecular markers are needed to find out more about the (subtle) phylogenetic differentiation between C. atovirens and C. ionochlorus.