R-L categories correct, but text here does not match final assessment. Updated version will be published in IUCN´s Red List June or Nov 2019.
Sarcodon joeides is a striking hydnoid fungus with large basidiocarps (pileus 5-10 cm), characterized the lilac-red to violet colour of the context. It has a fairly wide distribution in Western and Central Europe, but it is rare in its entire area and has decreased in many regions. S. joeides is an ectomycorrhizal symbiont of old Quercus and Fagus trees and appears to be very sensitive to nitrogen pollution. Also cutting of oak and beech trees contributes to its decline. It is assessed as Vulnerable (based on the criteria A2c and C1ai+2ai) based on an inferred decline of more than 30% during the past 50 years (three generations) and a small population size (maximum 8000 mature individuals).
Sarcodon joeides is also reported from North America (Baird et al., 2013), but these records are regarded as doubtful, i.a. in view of different spore size. Also a record from New Zealand may refer to a different species. These doubtful records are not considered in this assessment.
Sarcodon joeides is distributed in Northwestern and Central Europe.
Sarcodon joeides is known at present from about known 200 localities, with its centre of distribution in Northwestern Europe, with about 60 localities in the Netherlands, about 30 in Belgium and 16 in the lowland of northern Germany. Only known from one locality in Great-Britain. In Scandinavia only nine localities are known in Sweden and three in Norway (not in Denmark and Finland). The total number of localities in Europe, including unknown localities, is estimated at a maximum of 800, usually with 1-10 mycelial individuals each. Sarcodon joeides has strongly declined in the entire area since about 1950. In its entire distribution area a conservative estimate is a decrease of at least 35% in the last 50 years. It is red-listed as Critically endangered in Flandres, France and Norway; as Endangered in The Netherlands, Germany, Niedersachsen and Switzerland; as Vulnerable in Sweden.
Population Trend: Decreasing
Sarcodon joeides is an ectomycorrhizal symbiont of Fagus sylvatica and Quercus robur, probably also Q. petraea. It is associated with mature and old trees in native deciduous forests and in roadsides with planted trees 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 habitat, being natural forests of Quercus and Fagus on very poor sandy and loamy soils. At present it 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 refuges of Sarcodon joeides (Arnolds, 2003).
Sarcodon joeides is primarily threatened by nitrogen deposition. In addition, relict populations along roadsides are threatened by cutting of trees and inadequate management.
The most useful measure for conservation of this species would be a strong reduction of nitrogen pollution. In the Netherlands a reduction of 30% of nitrogen deposition has lead to some recovery of populations since 2000 in roadsides , however not to any re-establishment in its natural habitat in deciduous forests (Arnolds & Veerkamp, 2008). In the remaining relic localities in roadsideverges with trees also habitat protection (maintaining old trees) and a managemant regime of removal of grass and litter are important for maintaining this species
The taxonomic relationships between European populations and records listed as Sarcodon joeides in North America and New Zealand have to be studied with molecular methods.
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