Hydnellum scabrosum is an ectomycorrhizal fungus with wide distribution in the northern hemispere, in particular in the boreal biom. It forms ectomycorrhiza with pine in mainly older forest on mostly dry and acidic soil. It is easily identified as i forms conspicuous and large sporocarps, is used as an indictor species for forest of conservation interest and have been much searched after. Being a ectomycorrhizal fungus, the main threat to the species is clearcuttting as its mycelia withers and dies the in absence of living trees. It

The gobal population is estimated to have declined, and continuing to decrease of appropriate habitat due felling of dry natural and seminatural old pine forests with long tree continuity. It is nationally red-listed in a few contries with classifications ranging from LC to NT and CR.

Decline in area and quality of available habitat is estimated to be in the range of 20-25% over the last 50 years; the decline in population size over this time could be higher. This decline in habitat is expected to continue even more rapidly over the next 50 years (approximately three generations: one generation for the species is around 17 years). Currently The population size is large and only criterion A is applicable. This species meets the threshold for NT A2c+3c+4c.

Formally listed as a species of Sarcodon, this species is now classified as Hydnellum (Larsson et al 2019).

Sarcodon scabrosum is widely distributed in the northern hemisphere, mainly in the boreal biom but also in the temperate biom (GBIF 2024; Bendiksen and Brandrud 2014). Note that reports from the temperate zone may refer to other similar Hydnellum taxa as H. scabrosum sensu stricto only associate with Pinaceae trees (Nitare et al 2021).

Sarcodon scabrosum is a widely spread species. It has most of its occurences located in the the north and are only rarely reported from kontinental Europe. It is widespread in Canada and also stated as rather common in appropriate habitats in the USA and Russia. It is particularly well-known in the Nordic countries as it has been used as an indicator species for dry pine forests of conservation interest and therefore paid much attentention to (Nitare 2006; Nitare 2023). About 85% of the +13000 records of S. scabrosum in GBIF (2024) are from these countries. The total number of localities in Norway, Sweden and Finland are estimated to approxing 5000 (Artsdatabanken 2021; SLU Artdatabanken 2020; cf. Hyvärinen et al 2019). Each locality may have a few genotypes of S. scabrosum corresponding to 20-50 mature individuals (cf Dahlberg and Mueller 2011). Hence, the total global population is estimated to be substantially large.

Sarcodon scabrosum is nationally red-list assessed in a few countries (Denmark CR, Norway NT, Sweden NT and Finland LC; Moeslund et al 2023; Artsdatabanken 2021; SLU Artdatabanken 2020; Hyvärinen et al 2019). It hasnot been nationally red-list assessed in continental Europe, despite only relatively few records. In North America, it is classified as having a Secure status in Canada (Canadian Endangered Species Conservation Council. 2022).

The decline of the major habitat of the species, dry natural and seminatural dry older pine forests in Europe in the evaluation period of 50 years is estimated to be in the magnitude of 30-50% and projected to continue at that rate (Artsdatabanken 2021; SLU Artdatabanken 2020; cf Bendiksen and Brandrud 2014). Considering that the species to some extent appear to survive and/or re-establish in forest generated by clearcutting and that the status appear more favourable in North America, the total population is estimated to have declined 20-30 % due to forestry during the last 50 years. It is therefore assessed as Near Threathened (NT) based on the criteria A2c+3c+4c.The lenght period of evaluation is 50 years (= 3 generations according to the recommendations of Dahlberg & Mueller, 2011).

Hydnellum scabrosum is a large and characterisic ectomycorrhizal fungus associating with Pinaceae trees in dry, nurient-poor (acid) shallow soil, oligotrophic lichen dominated pine forests and in sandy pine forests (Bendiksen and Brandrud 2014; Nitare etal 2021). It occurs mainly in forests with remnants of natural forest elements and seminatural pine forests that have been selectively cut. Do sometimes also occur in younger pine forests resulting from clear-felling, due to either surviving mycelia on left retention trees or seedlings, or from mycelia established from wind-dispersed spores originating from nearby forests. Unclear, as for ectomycorrhizal fungi in general, if its spoes may form a sporbank in the soil.

Hydnellum scabrosum sensu stricto has been found to be an ectomycorrhizal partner of Pinaceae only (Nitare et al 2021). It has been veified to form mycorrhiza by DNA-squences in the roots of Pinus sylvestris, P. densiflora, Pseudotsuga menziesii and also to form mycorrhizal associations with epiparasitic monotropoid plant roots (Nitare et al 2021).

It is primarily threatened by clear-cutting of old-growth pine forests, nitrogen fertilization of forests, and measures to prevent forest fires (Artsdatabanken 2021; SLU Artdatabanken 2020; Brandrud and Bendiksen 2014).

Protection of known sites. It may also survive well in areas with forestry using carful selective cutting methods.

Reasearch is desired to gain a better understanding of its ecology, in particular its population biology. Basic knowledge of if and to what extent it may survive and re-establish in areas subjected to forest management would facilitate a needed better management of H. scabrosum.

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

Björnström H & Wikström P. 2023. Sandtallskogens marksvampar. Fältguide till de torra tallskogarnas fantastiska funga. (In Swedish: Fungi of sandy pine forest. A field guide to the amazing fungi of the dry pine forests). Mykologiska Publikationer 10. Sveriges Mykologiska Förening.

Brandrud, T. E. & Bendiksen, E. 2014. Fungi of sandy pine forests in Norway, and a comparison of this threatened element elsewhere in Europe(-Asia). Agarica 35: 67-87.

Canadian Endangered Species Conservation Council. 2022. Wild Species 2020: The General Status of Species in Canada. National General Status Working Group: 172 pp

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.

GBIF Secretariat (2024). Hydnellum scabrosum (Fr.) E.Larss., K.H.Larss. & Kõljalg in GBIF Backbone Taxonomy. Checklist dataset https://doi.org/10.15468/39omei accessed via GBIF.org on 2024-12-28.

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.

Larsson K-H, Svantesson S, Miscevic D, Kõljalg U and Larsson E. 2019.  Reassessment of the generic limits for Hydnellum and Sarcodon (Thelephorales, Basidiomycota).  MycoKeys 54: 31–47 doi: 10.3897/mycokeys.54.35386

Nitare J (2006). Åtgärdsprogram för bevarande av rödlistade fjälltaggsvampar (Sarcodon) [Action plan for red-listed species of Sarcodon in Sweden]. Naturvårdsverket, Rapport 5609, Sweden.

Nitare J, Ainsworth AM, Larsson E, Parfitt D, Suz LM, Svantesson S and Larsson K-H. 2021. Four new species of Hydnellum (Thelephorales, Basidiomycota) with a note on Sarcodon illudens. Fungal Systematics and Evolution 7: 233-254. doi.org/10.3114/fuse.2021.07.12

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

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