It was formerly listed as a species of Sarcodon, but Sarcodon has now been placed in synonomy with Hydnellum (Larsson et al. 2019). The species was described from Canada, but it has not been documented by sequencing that the species is the same in Europe and North America.

Hydnellum martioflavum is a rare ectomycorrhizal fungus associating with Picea on mostly calcareous soils in Europe and North America. It is most commonly reported Fennoscandia. It is typically found in habitats with diverse and rich funga (“hot spots”) in old undisturbed coniferous and mixed forests on calcareous soils. Outside of protected areas, these forests are declining, predominantly due to forestry logging practices. The species is nationally Red Listed 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 is predicted 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). Based on this, the species is assessed as Vulnerable (VU) A2c+3c+4c.

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, Czechia (not mapped), Germany and Switzerland. It is also present in Canada and USA (GBIF 2024).

It is known from approximately 75 sites in Norway, 50 in Sweden and fewer in Finland, according to data from national Red Lists and species database maps (SLU Artdatabanken 2020, Artsdatabanken 2021, Finnish Biodiversity Centre 2024). The total number of localities in Fennoscandia is estimated to be approximately 650 sites. It is estimated not to occur at more than 50 more sites in the remainder of Europe. The species' status and trend in the USA is unclear, but it is clearly very rare (GBIF 2024). The total global population is estimated to be fewer than 20,000 mature individuals, i.e. fewer than 1,000 sites and each site with on average 2-5 genetically unique mycelia (Dahlberg and Mueller 2011).

In Fennoscandia, where the majority of the population is located, the decline of the major habitat of the species, calcareous Picea forests, is estimated to be in the magnitude of 30-40% over 50 years due to forestry and clear-cutting (Hyvärinen et al. 2019, SLU Artdatabanen 2020, Artsdatabanken 2021). The decline of the species’ population size is suspected to be similar and continuing. The overall global population is suspected to have declined by more than 30% since 1975, which would roughly correspond to the three-generation evaluation period for ectomycorrhizal fungi, which is 50 years (Dahlberg and Mueller 2011).

It is an ectomycorrhizal fungus forming mycorrhiza with spruce (Picea abies) in old growth calcareous forests with long tree continuity (SLU Artdatabanken 2020, Artsdatabanken 2021, Nitare 2023). Preferred habitats are humid, with a well-developed mossy layer on fertile calcareous soils (rich in minerals) both on dry ridges and along brooks. Basidiomata are usually only few, occurring irregularly, mostly in cold years with above average atmospheric precipitation. Hydnellum martioflavum is an umbrella species, found in habitats with diverse and rich mycoflora (“hot spots”).

Being a rare ectomycorrhizal fungus, the main threat to Hydnellum martioflavum is clear-cutting, as its mycelia wither and die in absence of living trees. Due to its extreme rareness, recolonisation is unlikely. Additionally, H. martioflavum and its habitats (calcareous Picea forests) have been declining e.g. due to urbanization, including tourist resorts, road constructions, expansion of limestone quarries.

The species is not known to be used.

It is assessed as nationally Red Listed in multiple European countries; Vulnerable in Norway, Sweden and Switzerland, and Critically Endangered in Finland and Germany (Senn-Irlet et al. 2007, Dämmrich et al. 2016, Hyvärinen et al. 2019, SLU Artdatabanken 2020, Artsdatabanken 2021).

For the protection of Hydnellum martioflavum, the strictest protection of areas should be declared within its area of its occurrence. Most importantly these should be at small hot spots where there is overlap with the range of many threatened species. Research into its population biology, its general biology and needed habitat conditions is desired.