Hydnellum martioflavum is a rare ectomycorrhizal fungus associating with Picea on mostly calcareous soils in Europe ande North America. It has its largest known occurence in Fennoscandia.
It is typically found in habitats with diverse and rich funga (“hot spots”) in old undisturbed coniferous and mixed forests on calacareous soils. Outside protected areas, these forests are declining due to forestry logging practices. The species is nationally redlisted in most countries of its occurrence.

The decline of the major habitat of the species, Fennoscandinavian calcareous Picea forests, is in the magnitude of 30-40% since 1975 and estimated to continue to be at that level. The decline of the species to be in the same magnitude, and to globally to exceed 30% over 50 years (approximately three generations: one generation for the species is around 17 years). Based on this, the species is assessed as Vulnerable (VU)  according to the A-criterion (A2c+3c+4c).

Sarcodon martioflavus is easy to identify, rather rare species of the Bankeraceae family. It occurs in old growth coniferous forests with long term continuity and natural occurrence of spruce, with which it is forming mycorrhiza. Preferred habitats are humid, with well developed mossy layer on fertile calcareous soils (rich in minerals). Basidiomata are usually only few, occurring irregularly, mostly in cold years with above average atmospheric precipitation.
The species is threatened by inappropriate forest management, clear cutting of suitable habitats – old growth spruce forests. Further threats include air pollution and global climate change, with sudden temperature and rain fluctuations, lack of precipitation and its uneven distribution over the year, as well as drying of habitats.

Hydnellum martioflavum is a rare European and North American species. The most numerous findings are documented from Fennoscandinavia (Sweden, Norway and Finland). It rarely occurs in other countries of Central and Western Europe, such as Slovakia, Czech Republic, Germany and Switzerland. Also present in Canada and USA (GBIF 2024).

It is known from approx. 75 sites in Norway, 50 in Sweden and fewer in Finland, according to data from national redlists and species database maps (Artsdatabanken 2021; SLU Artdatabanken 2020; Finnish Biodiversity Centre 2024). The estimated total number of localites in Fennoscandia is estimated to approximately 650 sites. It is estimated not to occur at more than 50 more sites in remaining Europe. The speciea´status and trend in the USA is unclear, nut it is clearly very rare (America (GBIF 2024; ). The total global population is estimated to be less than 20 000 mature individuals, i.e. less than 1000 sites and each sites with on average 2-5 geneticallay unique mycelia (Dahlberg & Mueller 2011). It is assessed as nationally red-listed in multiple European countries (VU in Norway, Sweden and Switzerland and CR in Finland and Germany (Artsdatabanken 2021; SLU Artdatabanken 2020; Senn-Irlet et al 2017; Hyvärinen et al 2019; Dämmrich et al 2016)).

In Fennoscandia where the main population is located, the decline of the major habitat of the species, calcareous Picea forests estimated to be in the magnitude of 30-40% over 50 years due to forestry and clearcutting (Artsdatabanken 2021; SLU Artdatabanen 2020; Hyvärinen et al, 2019). The decline of the species’ population size is estimated to be similar. The overall global population is estimated to have declined with more than 30% since 1975. The lenght period of evaluation for ectomycorrhizal fungi is 50 years (= 3 generations according to the recommendations of Dahlberg & Mueller, 2011).  Hence, it is assessed as Vulnerable (VU) based on the criteria A2c+3c+4c.

It is an ectomycorrhizal fungus forming mycorrhiza with spruce (Picea abies) in old growth calcareous forests with long tree continuity (Artsdatabanken2021; SLU Artdatabanken 2020; Nitare 2023). Prefered habitats are humid, with well developed mossy layer on fertile calcareous soils (rich in minerals) both on dry rigdes and along brooks. Basidiomata are usually only few, occurring irregularly, mostly in cold years with above average atmospheric precipitation. Sarcodon martioflavus is an umbrella species, found in habitats with diverse and rich mycoflora (“hot spots”).

Being a rare ectomycorrhizal fungus, the main threat to H. martioflavum is clearcuttting as its mycelia in absence of living trees withers and dies. Due to its extreme rareness, recolonisation is unlikely

Protection of known sites.

Research into its population biology, its general biology and needed habitat conditions are desired.

The species is not known to be used.

Artsdatabanken (2021). Norsk rødliste for arter 2021. (Red-listed species in Norway 2021).  Artsdatabanken, Trondheim. ISBN:  978-82-92838-56-3

Dahlberg A & Mueller G. 2011. Applying IUCN red-listing criteria for assessing and reporting on the conservation status of fungal species. Fungal Ecology 4: 1-16.

Dämmrich, F., Lotz-Winter H., Schmidt M., Pätzold W., Otto P., Schmitt J.A., Scholler M., Schurig B., Winterhoff W., Gminder A., Hardtke H.J., Hirsch G., Karasch P., Luderitz M., Schmidt-Stohn G., Siepe K., Täglich U. and Wöldecke K. (2016). Rote Liste der Großpilze und vorläufige Gesamtartenliste der Ständer- und Schlauchpilze (Basidiomycota und Ascomycota) Deutschlands mit Ausnahme der Flechten und der phytoparasitischen Kleinpilze.

GBIF Secretariat (2024). Hydnellum martioflavum (Snell, K.A.Harrison & H.A.C.Jacks.) E.Larss., K.H.Larss. & Kõljalg in GBIF Backbone Taxonomy. Checklist dataset https://doi.org/10.15468/39omei accessed via GBIF.org on 2024-12-27.

Hyvärinen, E., Juslén, A., Kemppainen, E., Uddström, A. & Liukko, U.-M. (eds.) 2019. The 2019 Red List of Finnish Species. Ympäristöministeriö & Suomen ympäristökeskus. Helsinki. 704 p.https://punainenkirja.laji.fi/en

KŘÍŽ, M. 2017. Sarcodon martioflavus in the Czech Republic, p. 33 – 40 In: Mykologicke listy, Praha, no. 136, 2017.

Nitare J. 2023. Skyddsvärd skog: naturvårdsarter och andra kriterier för naturvärdesbedömning (In Swedish: Protected forest: nature conservation species and other criteria for nature value assessment). 3rd ed. Skogsstyrelsen. Jönköping. ISBN 987-91-986297-0-5

Senn-Irlet B., Bieri G and Egli S. (2007). Rote Liste Grosspilze. Rote Liste der gefährdeten Arten der Schweiz Ausgabe 2007

SLU Artdatabanken (2020). Rödlistade arter i Sverige 2020. (Red-listed species in Sweden 2020) SLU, Uppsala ISBN 978-91-87853-54-8