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.
Hericium erinaceus is widely distributed in the Northern Hemisphere, mainly in temperate beech and oak forests of North America and Eurasia. In some regions, it is common and frequent, while in the other it is rare or very rare, and declining. It grows mainly in forests, on old living oak and beech trees and large diameter dead wood. The population size is likely to be very large since this is such a widespread species. The overall assessment is Least Concern (LC) because it is not assessed to decline globally to meet IUCN criteria for any threat category. However, nationally and regionally it is documented to decline because of habitat degradation and loss; removing old, damaged or dead trees and large diameter dead wood, and declining of temperate beech and oak forests in general.
syn. Hydnum erinaceus Bull. (1781)
Molecular analysis of 26 ITS sequences of Hericium erinaceus from North America (USA, Canada), East Asia (Japan, Korea, China, Malaysia) and Europe (Holland, UK) reveals three subclades with weak support values showing clear discrimination between specimens originating from USA, East Asia and UK (Hallenberg et al. 2013). More research is needed to elucidate if the fungi occurring in America, Asia and Europe and believed to be H. erinaceus represent the same species. For the present evaluation of the global threats and conservation status, the species is considered as one and the same across the whole distribution range.
Hericium erinaceus is a species associated mainly with temperate beech and oak forests of North America and Eurasia. It growths on old living oak and beech trees and large diameter dead wood. Although in some regions it is common, in the other it is rare or very rare, and declining due to the habitat degradation and loss and because of removing old, damaged or dead trees and large diameter dead wood. The species is red-listed as well as protected by law in many European countries.
The species is widely distributed in the Northern Hemisphere. It is rather common in North and Central America (USA, Mexico, Costa Rica), in Colombia, and is widespread in Eurasia. In Canada, its presence has not been confirmed - all Canadian cultures labelled H. erinaceus were reassigned to H. americanum (Ginns 1985). In Europe, it is known from the majority of countries, although the number of localities varies greatly with maximum occurrence in France, then Great Britain, Germany, the Netherlands and Spain. In the remaining countries it is rare or very rare (Dahlberg and Croneborg, 2003). In Asia, the species occurs at widely scattered localities from the Caucasus through Central Asia to the Russian Far East, China, Korea, Japan, India, Borneo and Australia (Piątek, 2005; Fraiture and Otto, 2015).
The species is widespread and abundant in the central and southeast USA (e.g., South Carolina and California) throughout the oak zone, in central and southern France, it is also not rare in Great Britain, Germany, the Netherlands and Spain. However, in other European countries, it is rare or very rare; it seems not to occur in the Boreal, Sarmatic and Steppic domains. In Russia (both European and Asian parts), the species is very rare. Other known Asian localities are rather scattered (the species is rare in the wild in China), although in some regions they are numerous (e.g., in East Asia and in Japan). In many countries, especially where the species is rare, a decline of the locality number was reported (e.g., in Sweden, Denmark, Greece, Hungary, Romania, and France). In the UK, an increase in the number of sites was observed (Fraiture and Otto, 2015) but it reflects rather more effective site recording. The occurrence of the species strongly depends on the presence of a proper substrate - mainly old and large beech or oak trees, large diameter dead wood, and rather more humid and mild climate. It is threatened by removal of old, deformed, or damaged trees from the stands, and decline of beech and oak forests in general. Population trends in H. erinaceus have been assessed over 50 yrs, estimated to correspond to three generations (cf. Dahlberg & Mueller, 2011). The species is red-listed in Austria, Belgium (regional red list), Bulgaria, Czech Republic, Denmark, France, Germany, Hungary, Luxembourg, Macedonia, Netherlands, Poland, Russia (regional red list), Serbia, Slovakia, Sweden, Switzerland and (unofficially) in the UK. It is protected by law in Croatia, Hungary, Poland, Serbia, Slovenia, Sweden and the UK.
Population Trend: Uncertain
The species is probably a week necrotrophic parasite on old deciduous and sclerophylous trees: mainly Fagus and Quercus (cerris, frainetto, gussonei, ilex, petraea, pubescens, robur), more seldom also Aesculus hippocastanus, Albizia julibrissin, Alnus glutinosa, A. incana, Carpinus betulus, Populus tremula, and Tilia cordata; occasionally it can grow on Betula, Fraxinus, Juglans, Malus, Ailanthus and Sorbus (Fraiture and Otto 2015). In Europe, it prefers beech and oak wood: it grows mainly on Fagus in the UK, Denmark and Poland, on Fagus and Quercus in the Czech Republic and Austria, predominantly on Quercus but also on Fagus in Slovakia, and almost exclusively on Quercus in Hungary (Kunca and Čiliak 2017; T. Læssøe pers. comm.). In N America, most frequently it habits oak and less frequently beech, and occasionally other trees (Harrison 1973; Boddy et al. 2011). It usually invades trunks and thick branches through lesions and causes white rot. It can continue its growth as a saprotroph after the host’s death; fruitbodies are also found on standing broken trunks, logs and stumps. The species seems to grow on the central part of the trunk and produces basidiomata only after its “disclosure” through injuries, cracks, cuttings, ect. It is a long-lived organism, basidiomata can appear for many years at the same place (trunk, log). The species usually occurs in forests, and in most cases is a good indicator for old-growth beech and oak forests. However, its presence in biotopes other than forest was recorded – e.g., in steppe on the Robinia pseudoacacia trunk and in an urban area on an ancient specimen of Fagus sylvatica in the warmest region of Slovakia, as well as in the urban area in Greece (on pruned Albizia). The fungus is included in the list of 21 fungal indicator species of the conservation value of European beech forests (Christensen et al., 2004). It grows both in preserved and in regularly managed forests but almost always on old trees. However, it was reported also on young living beech trees (15-20 cm in diam) in Krasnodar territory in Russia.
Loss of habitats is the main threat for the fungus: decline of old growth temperate beech and oak forests, elimination of old, especially badly shaped or injured/broken oak and beech trees (for pelleting, firewood, or for phytosanitary reasons), and removing large diameter dead wood from the forest. In Russia, significant decrease of oak forests (about 20% from 1966 http://www.pandia.ru/text/77/485/2455.php) was recorded. In Greece, Albizia julibrissin trees are infected and killed by Fusarium oxysporum f.sp. perniciosum; as a result park authorities stopped using this tree in gardens, parks and boulevards, thus eliminating the host for Hericium erinaceum. Another threat is heavy picking of basidiomata by mushroom lovers and for medicinal purposes.
In some areas in Denmark, where forest management has become more sustainable and felling old growth forests has been limited, the number of the species occurrences increased (T. Læssøe, pers. comm.).
The species is red-listed in more than a half of the European countries in which it had been recorded (Dahlberg and Croneborg, 2003; Fraiture and Otto, 2015). It is legally protected in Croatia, Hungary, Poland, Serbia, Slovenia, Sweden and the UK.
A part of the European localities of the species is situated in the area of National Parks and nature reserves (e.g., in Slovakia and Poland). This increases conservation effectiveness through habitat protection.
In Greece, there has not been any conservation action so far apart from informing societies of mushroom lovers about the rarity of the fungus and the threatening factors.
The conservation actions recommended regionally are preserving old growth temperate beech and oak forests, sustainable forest management including conservation of old beech and oak trees as well as leaving sufficient amount of large diameter dead wood in forests.
As the species can be cultivated, it is advised to further develop its production and not to collect the species from the wild for culinary/medicine purposes.
Monitoring of the sites of occurrence and recognizing population trends. Molecular studies focused on clear discrimination of Hericium taxa and intraspecific diversity within H. erinaceus, with regard to the distribution ranges and ecological requirements. Research on the biology of the species, ways of its establishment in trees, selectivity towards different wood types, agents stimulating the production of basidiomata in the wild, fruiting patterns, longevity, and ecological requirements.
The fruitbodies of the species are edible and heavily collected for this reason in some regions, e.g., in America and East Asia. Also, they are known for pharmaceutical properties and are used especially in traditional Chinese medicine. The cultivation is relatively easy and fruitbodies are the subject of trade.
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Christensen M., Heilmann-Clausen J., Walleyn R., Adamčík S. 2004. Wood-inhabiting fungi as indicators of nature value in European beech forests. [In:] Marchetti M. (Ed.), Monitoring and Indicators of Forest Biodiversity in Europe – from Ideas to Operationality. European Forestry Institute Proceedings 51, Saarijarvi, p. 229–237.
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Hallenberg N., Nilsson R.H., Robledo G. 2013. Species complexes in Hericium (Russulales, Agaricomycota) and a new species - Hericium rajchenbergii - from southern South America. Mycol Progress 12: 413–420.
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Kunca V., Čiliak M. 2017. Habitat preferences of Hericium erinaceus in Slovakia. Fungal Ecol. 27, Part B: 189–192.
Piątek M. 2005. Hericium erinaceum (Bull.) Pers. [In:] Wojewoda W. (ed) Atlas of the geographical distribution of fungi in Poland 3: 43-46. W Szafer Institute of Botany, Polish Academy of Sciences, Kraków.
Sikora A., Neubauer G. 2015. Nowe stanowiska i występowanie soplówki jeżowatej Hericium erinaceus w Polsce [New sites and occurrence of the Bearded Tooth Hericium erinaceus in Poland]. Chrońmy Przyr. Ojcz. 71 (5): 368–379.