Assessment Notes

Justification

Sarcodon joeides is a striking hydnoid fungus with fairly large basidiomata, recognized by lilac-red to violet colour in the flesh. It has a wide distribution in Europe and is also present in the eastern US, but it is rare everywhere and has considerably decreased throughout its area. Sarcodon joeides is an ectomycorrhizal symbiont of old Quercus and Fagus trees and appears to be sensitive to nitrogen deposition. In addition, cutting of old oak and beech trees contributes to its decline. The habitat of S. joeides is inferred to have decreased by 35% during the past 50 years, the decline is ongoing and suspected to continue in the future. The habitat decline is suspected to correspond to a similar decline in population size.

---

Taxonomic notes

Recent specimens from America analysed by sequences revealed S. joeides to be present together with a yet not described sister species. One old record from New Zealand (Maas Geesteranus, 1971) probably belongs to a different species. Sarcodon joeides in Europe may also contain cryptic species, however, here  we consider it as one species.

---

Geographic range

Sarcodon joeides has a European distribution following Quercus and Fagus. It is also recorded in North America (Appalachian Mountains).

---

Population and Trends

Sarcodon joeides is known at present from about known 200 localities in Europe, with its centre of distribution in northwestern Europe (about 60 localities in the Netherlands, about 30 in Belgium and 16 in the lowland of northern Germany). It is only known from three localities in Great-Britain. In Scandinavia only nine localities are known in Sweden and three in Norway (none in Denmark and Finland). The total number of localities in Europe, including unknowns, does probably not exceed 1000, usually with 1-10 functional individuals each. The population size in the US is not known, but GBIF reports 50 occurrences. In mushroomobserver, five localities are reported from US and Canada between 2008-2018. Sarcodon joeides has strongly declined in the entire European area since about 1950. A similar trend can be suspected in the US as only two out of 50 specimens recorded are from after the year 2000 (Mycoportal.org). Hence, it is conservatively estimated to have decreased of at least 35% in the last 50 years (three generations) in Europe. It is red-listed as Critically endangered in Austria, Flandres, France and Norway; as Endangered in The Netherlands, Germany, Niedersachsen and Switzerland; as Vulnerable in Sweden.

Population Trend: decreasing

---

Habitat and Ecology

Sarcodon joeides is an ectomycorrhizal symbiont of Fagus and Quercus. It is associated with mature and old trees in native deciduous forests on mesic to dry, sandy and loamy soils with a thin litter layer and very low nitrogen contents. In the Netherlands and Belgium the species has completely disappeared from its original habitats and only occurs in secondary habitats, viz. well-managed roadsides with old oak and beech trees that were originally planted. These sites can be considered as man-made refuges of S. joeides (Arnolds 2003).

---

Threats

Sarcodon joeides is mainly found in half-open ancient woodlands with Quercus or Fagus. This habitat is rapidly decreasing in northern and central Europe due to felling of trees and changes in management, e.g. abandoning of extensive grazing. The species disappears after felling of host trees and does not colonize young, planted stands. In western Europe Sarcodon joeides is threatened in the first place by increased nitrogen deposition (Arnolds 1989, 2010). The critical nitrogen load for this species is probably below 20 kg N/ha/yr, an amount exceeded in large parts of its distribution centre in NW-Europe. The species shows some recovery in the Netherlands since 2000, due to decreasing levels of nitrogen deposition. However, the original forest sites where S. joeides occurred have not yet been recolonized (Arnolds, 2010). The relict populations in roadside-verges  are threatened in addition by cutting of trees and inadequate management. Many localities in roadside-verges have been lost by soil disturbance and abandoning of regular mowing, leading to a tall and dense sward; an inappropriate habitat for this critical fungus.

---

Conservation Actions

The most important measure for conservation of this species is site protection. In roadside localities with the old trees, gentle removal of grass and litter are important for maintaining this species. Another important measure would be a strong reduction of the nitrogen pollution. In the Netherlands, a reduction of 30% of the nitrogen deposition has led to some recovery of populations since 2000 in roadsides, however not to any re-establishment in its natural habitat in deciduous forests (Arnolds and Veerkamp 2008).

---

Use and Trade

The species is not known to be used.

---

Source and Citation

Arnolds, E. & Krisai-Greilhuber, I. 2019. Sarcodon joeides. The IUCN Red List of Threatened Species 2019: e.T75124333A75124572. https://dx.doi.org/10.2305/IUCN.UK.2019-2.RLTS.T75124333A75124572.en .Accessed on 2 February 2023

---

• Country occurrence