Assessment Notes

Justification

Cortinarius odoratus is a very rare European mycorrhiza-species associated mostly with Quercus and Carpinus confined to semi-open, xerothermic broadleaved forests on shallow calcareous soils. At present it is known in less than 50 localities in Europe (including European Russia) confined to a rare type of calcareous forest habitat. This species is one of the typical indicator of “hot-spots” in forest ecosystems always occurring together with other rare and threatened fungi as well as some plant species.

The species is mainly threatened by deforestation and other changes of habitats and traditional land-use, i.e. clear-cutting, replacement of mosaic forests into monoculture of similar-aged stands, abandonment of extensive grazing resulting in semi-open, heterogenic woodlands. The scale of this habitat loss in area and quality is suspected to be 15-30% in a 50 year time span including past, present and future.

The species is known from 50 localities in Europe, from this the total population is estimated to comprise 200 localities which correlate to ~4,000 mature individuals (population size <10,000 individuals), distributed in small subpopulations. There is an estimated continuing decline in the population size inferred from the habitat decline, and the subpopulations are assumed to have less than 1,000 mature individuals. The species is therefore assessed as VU under criterion C2a(i).

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Geographic range

So far this species is mainly known from the Western Palearctic with scattered records from South-Central Europe, southern parts of Scandinavia east to Stavropol Krai (Caucasus) and Penza Oblast (Russia), west to Belgium-France and south to the Apennines, Italy.

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Population and Trends

In total about 50 localities are known: Sweden (6 localities), Austria (1), Germany (17), Denmark (12), Russia (4), France (2), Czechia (2), Slovenia (6), Italy (less than 10), Spain (1) and Hungary (1). Since Cortinarius odoratus associates with Quercus, Corylus and Fagus, and these types of communities are constantly and evidently decreasing because of natural and anthropogenic reasons (i.e. area of oak forests - about 20% since 1966 (Grigorjev et al. 2000)), we can suppose past and future declining of species. In Russia, C. odoratus is recommended to be included in the federal Red Data Book; at present it is included in the Red Data Book of Penza Oblast.

It can be estimated that in Europe and globally there are about 200 localities including those currently unknown. The number of mature individuals is approx. 4,000 and definitely less than 10,000. The habitat loss (past and ongoing) exceeds 15% for three generations (50 years for ectomycorrhizal fungi). The number of mature individuals in each subpopulation is below 1,000.

Population Trend: decreasing

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Habitat and Ecology

This is an ectomycorrhizal fungus growing with deciduous trees (mainly Quercus, Carpinus, Fagus) in continental areas with favourable local climate (warm) on calcareous and shallow soils (e.g. leptosol). It can be found in closed-crown deciduous forests and in open forest as well. However, an important feature of habitat is a thick and well-structured litter. Since the mycelium of this fungus typically spreads between this litter and upper soil layer, the disturbance and removal of the litter leads to the disappearance of the species.

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Threats

These semi-open natural broad-leaved habitats have been going through dramatic changes in the last 100 years through either 1) Clear-cutting, replacement of mosaic forest types into monoculture of similar-aged stands (i.e. more productive forests of single tree species and/or to more uniform forest structures with less variation) or 2) being abandoned from earlier traditional land use such as extensive grazing, pollarding and selective small-scale tree-felling resulting in a densification and change in forest structure detrimental to the species.

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Conservation Actions

In Sweden there is an Action plan for the species (Knutsson 2014) and the species is included in the Red Data Book of Penza Region (2013). So far it has resulted in a great increase in knowledge about ecology, habitats and management of sites but only very few observations of the species were made. A few of the known localities where affected by logging during the study. The actions suggested to conserve the species are mainly focused on area/site protection from logging and restoration of habitats incl. shrub removal, selective tree-felling and reintroduction of cattle to graze the semi-open natural forests.

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Use and Trade

The species is not used.

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Source and Citation

Knutsson, T., Svetasheva, T. & Brandrud, T.-E. 2019. Cortinarius odoratus. The IUCN Red List of Threatened Species 2019: e.T70425822A70425931. https://dx.doi.org/10.2305/IUCN.UK.2019-2.RLTS.T70425822A70425931.en .Accessed on 3 February 2025

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• Country occurrence