Assessment Notes

Justification

Hericium erinaceus is a wood inhabiting widely distributed fungus, mainly in temperate beech and oak forests of North America and Eurasia. In some regions it is common and frequent, while in others it is 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 it is widespread. The species is assessed as Least Concern (LC). However, nationally and regionally it is documented to be declining due to habitat degradation and loss.

---

Taxonomic notes

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.

---

Geographic range

The species is widely distributed in the Northern Hemisphere. It is rather common in North and Central America, in Colombia, and is widespread in Eurasia. In Canada, its presence has not been confirmed, all Canadian mycelial 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 most records in France, followed by Great Britain, Germany, the Netherlands and Spain. In the remaining countries it is rare to very rare (Dahlberg and Croneborg 2003). In Asia, the species was reported from widely scattered localities from the Caucasus through Central Asia to the far eastern Russia, China, Korea, Japan, India, Borneo and Australia (Piątek 2005, Fraiture and Otto 2015).

---

Population and Trends

The species is widespread and abundant in the central and southeast USA (e.g., South Carolina and California) throughout the oak zone, and 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, and Arctic domains. (Dahlberg and Croneborg 2003, Fraiture and Otto 2015). 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, 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 is mentioned (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 for the application of Criterion A are assessed over 50 yrs, estimated to correspond to three generations (cf. Dahlberg and Mueller 2011). 

The species is included on Red Lists in Austria, Belgium (regional red list), Bulgaria, Czechia, Denmark, France, Germany, Hungary, Luxembourg, North Macedonia, Netherlands, Poland, Russia (regional Red Data Books), 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: decreasing

---

Habitat and Ecology

Hericium erinaceus is probably a weak necrotrophic parasite on old deciduous and sclerophylous trees, mainly Fagus and Quercus (Q. 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 also grow on Betula, Fraxinus, Juglans, Malus, Ailanthus and Sorbus (Fraiture and Otto 2015). In Europe, it preferentially grows on beech and oak in UK, Denmark, Poland, Czechia and Austria, predominantly on oak but also on beech in Slovakia, and almost exclusively on oak in Hungary (Kunca and Čiliak 2017). In North America, most frequently it inhabits oak, less frequently beech and occasionally other trees (Harrison 1973, Boddy et al. 2011). It usually colonizes trunks and thick branches through lesions and causes white rot. It can continue its growth as a saprotroph after the trees death. Therefore, fruitbodies are also found on standing broken trunks, logs and stumps. The species seems to grow in the central part of the trunk and fruitbodies develop through injuries, cracks and cuttings, etc. It is a long-lived organism as mycelium and its annual sporocarps can appear for many years at the same trunk or log. The species usually occurs in forests, and it is considered to be a good indicator for old growth beech and oak forests. However, it also occurs in other habitats, e.g., in steppe on Robinia pseudoacacia, or on ancient solitary veteran trees in anthropogenic habitats. The fungus is included in the list of 21 fungal indicator species of conservation value of European beech forests (Christensen et al. 2004). It grows both in preserved and in managed forests, but almost always on old trees. However, it has been reported also on young living beech trees.

---

Threats

Loss of habitats is the main threat for the fungus, decline of old growth temperate beech and oak forests, removal of old, especially badly shaped, injured or broken oak and beech trees for firewood, or phytosanitary reasons, and removing large diameter dead wood from the forest. Oak forests in Europe have been declining due to logging and changed land use (Denman et al. 2014). Potentially, diseases may also be a threat (Hansen and Delatour 1999). Another threat is heavy harvesting of fruitbodies because of its edibility and for medicinal purposes.

---

Conservation Actions

This species is legally protected in Croatia, Hungary, Poland, Serbia, Slovenia, Sweden and the UK. Some of the European localities of the species are situated in the area of national parks and nature reserves. This increases conservation effectiveness through habitat protection. 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. Interestingly, 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.). 

As the species is easily cultivated, it is advised to further develop its production and not to collect the species from the wild for culinary and medicine purposes. However, cultivation of Hericium erinaceus using imported, non-native mycelia could pose a threat to native populations if basidiospores released from cultivated fruitbodies or the mycelium from the remaining substrate, establish into the natural environment. 

Molecular studies focused on discrimination of Hericium taxa and intraspecific diversity within H. erinaceus are recommended 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, longevity, and ecological requirements is needed. Monitoring of the sites of occurrence and recognizing population trends is recommended.

---

Use and Trade

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.

---

Source and Citation

Kałucka, I.L. & Olariaga Ibarguren, I. 2019. Hericium erinaceus. The IUCN Red List of Threatened Species 2019: e.T70401627A70401637. https://dx.doi.org/10.2305/IUCN.UK.2019-3.RLTS.T70401627A70401637.en .Accessed on 2 February 2024

---

• Country occurrence