Assessment Notes

Justification

Cortinarius citrino-olivaceus is a mycorrhizal species associated with Abies alba and rarely with Pinus sylvestris. It belongs to the rich fungus element of the (mixed) calcareous Abies alba forests of central Europe (Brandrud et al. 2015).  Many of the species occurring here have a limited host range, edaphic requirements and distribution. Some occurs both in calcareous fir- and calcareous oak-beech forests, some occur both in calcareous fir- and calcareous spruce-pine forests, but some occurs only/mainly in Abies alba forests, such as the present one, Cortinarius atrovirens, C. haasii, C. subgracilis and Hygrophorus pudorinus. These species, is suffering from decline in the small and fragmented calcareous fir forests of e.g. Black Forest, the Jura, Pre-alps and the Carpaths, due to e.g. areal loss in more heavy populated areas and loss/fragmentation of older coniferous forest stands from modern (clear-cut) forestry.

Cortinarius citrino-olivaceus and its habitat is assessed to be subjected to continuous decline, and the population is small (<10,000 mature individuals) and restricted (5,000 sites) with very small subpopulations, C. citrino-olivaceus is assessed to meet the criteria for  listing as Vulnerable under C2a(i). In addition the decline in old-growth, calcareous Abies forests due to forestry and habitat-loss is estimated to approximately 15-20% over a three generation time period (past and future). Based on this the species meets the criteria to for a Near Threatened (NT) listing based on the A criterion (A2c+3c+4c)

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Geographic range

Cortinarius citrino-olivaceus has a limited, disjunct/fragmented European distribution, with a core area in certain Abies districts of the Pre-alps and some outposts in Pinus forests at Gotland and in the Pyrenees (Moser 1961, Ballarà et al. 2011, Brandrud et al. 2015). Recorded from eastern France, northern Italy, Austria, northeast Spain and southeast Sweden (Gotland). So far no certain records are known from the northern flank of calcareous Abies alba forests in Germany, the eastern-southeastern flanks in the Carpaths, nor the southern flank of the Apennines, central Italy. Among the better investigated calcareous Abies forest areas, the species is completely lacking from the Black Forest area, and appears very rare in the Jura, whereas the species is more distributed in Tyrol. This pattern may indicate that the species has a slightly eastern-continental distribution within the calcareous Abies alba forest range, and the species might be occurring also farther east-south-east, e.g. in the limestone-dolomite areas of southeast Pre-alps of Slovenia and the west Carpathians, in districts which are up to now little surveyed for Cortinarius species.

Cortinarius citrino-olivaceus, as well as the other, more or less strict members of this calcareous Abies alba element (such as Cortinarius atrovirens), are not reported from outside Europe.

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Population and Trends

Cortinarius citrino-olivaceus is among the rarest taxa within the calcareous Abies alba forest element. It has a core area in montane, dolomite areas in Tyrol in the eastern Pre-alps (Brandrud et al. 2015). Collections from approx 10 localities in Austria and two from adjacent N Italy are available. The species is furthermore found in the French Jura (east France; on limestone plateaus), but must be very rare here, since lacking in the extensive publications on Cortinarius from the area. Finally, the species is recorded from Pyrenees (northeast Spain) and from three, possibly four sites at the limestone island of Gotland, southern Sweden. Known, verified records are summing up to approx. 20, and the real number of sites/localities is estimated to be approx. 200-300, corresponding with a total of 4,000-6,000 mature individuals (see Dahlberg and Mueller 2011).

According to the sites seen, the species is mainly associated with older coniferous forest stands, without influence of modern forestry with clear-cuts. These habitats are declining in the core area of Tyrol, due to increased forestry (see under Threats). The three, known localities from Gotland, Sweden are from extremely calcareous, formerly grazed pine forests, being hotspots for threatened coniferous forests species in general, but more specificially, also housing several outpost localities for typical Abies alba species such as Cortinarius atrovirens, C. haasii, and C. subgracilis. These forests are now declining on Gotland (see under Threats).

The Central European silver fir forests have also regionally been seriously declining during the latest 50 years due to long transboundary air pollution leading to forest die-back. However, the pollution and its effects are now decreased, and is furthermore effecting mainly less calcareous forest stands.

Population Trend: decreasing

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Habitat and Ecology

Cortinarius citrino-olivaceus is a mycorrhizal associate mainly with Abies alba, but in outposts outside the natural distribution area of Abies also with Pinus sylvestris (Spain, Sweden). The species was initially described from Picea abies forests of N Tyrol, Austria, but on examination of collected material from N Tyrol, needles from both Abies alba and Picea abies were found on the fruitbodies, indicating that this actually occurs in mixed Abies-Picea forests. All central European records are from Abies forests or from mixed Abies-Picea forests, where the species is found together with other Abies specialists such as C. atrovirens. The species is never found in pure Picea forests, and never in Picea-dominated regions outside the Abies alba range. It is therefore concluded that this is an Abies forest associate in Cental Europe. The species occur in mossy, calcareous forests, in Tyrol mainly on dolomite ground, elsewhere on limestone. The sites at Gotland are strictly calcareous, and the species occurs with other strictly calciphilous fungi.

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Threats

Cortinarius citrino-olivaceus is threatened by loss, depauperation and fragmentation of intact, calcareous fir and pine forest habitats, due mainly to intensive forestry. The montane forests in Tyrol, where the species has its major area, have had an increased forestry activity, with a doubling of annual felling the last 40 years, according to forestry statistics (Austria). Furthermore, a habitat-loss is probably seen in many silver fir regions due to settlement expansion, road construction, ski tracks, etc. The narrow bands of Abies forests in the Alp valleys may also be vulnerable to climate change. The mature, calcareous pine forests at Gotland (Sweden) are also declining, due to forestry and areal loss due to expansion of limestone quarries, as well as altered management practices (incl. loss of cattle grazing), leading to depauperate habitat qualities for the strictly calciphilous pine forests species species (J. Nitare pers. comm.).

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Conservation Actions

To prevent decline and fragmentation of calcareous fir (-pine) forests with good habitat quality, it is important to set aside reserves on calcareous hotspots, housing many rare/red-listed species such as Cortinarius citrino-olivaceus and C. atrovirens. It is furthermore important to establish woodland key biotopes and similar kinds of forest stand where a non-intensive, closed cutting is performed, leaving much of the stand qualities intact, including a continuity in the fir/pine roots and their mycorrhizae.
There is a need for further mapping/surveying of the species, especially in more eastern regions of calcareous silver fir forest habitats, such as the southeastern Pre-alps of Slovenia and the western  Carpathians of Slovakia.

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Use and Trade

The species is not known to be used.

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Source and Citation

Brandrud, T.-E. 2015. Cortinarius citrino-olivaceus. The IUCN Red List of Threatened Species 2015: e.T79515429A79515433. https://dx.doi.org/10.2305/IUCN.UK.2015-4.RLTS.T79515429A79515433.en .Accessed on 3 February 2024

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• Country occurrence