Hydnellum gracilipes is a strange, hydnoid fungus with a reduced, thin stipe, and a thin pileus normally attached to the underside of old, often burned logs. The species forms mycorrhiza with Pinus sylvestris, and is confined to old-growth, often more or less pristine, sandy pine forests. Hydnellum gracilipes is regarded as an indicator species of old-growth forest conditions, with downed logs and influence from forest fires, and is therefore vulnerable to (clear-cutting) forestry, fragmentation of old-growth forest patches, and a nowadays a reduced frequency of fires.
It suffers from decline in the proportion of old-growth forests with intact, natural disturbance regimes in all parts of its distributional area. The proportion of forested areas with clear-cuts is decreasing with approx. 1% per year nowadays in Sweden and Finland. Furthermore, sandy pine forests are regionally declining, due to (i) change in land-use/urbanization, and (ii) eutrophication/increased N-loads. Altogether, a habitat-loss of >30% during 50 years isconsidered.
The species seems to be almost confined to the Fennoscandian, boreal Scots pine forest, and is redlisted in both Norway, Sweden and Finland.
Preliminary global and European Red List assessment;
VU (A2c+3c+4c), with an estimated decline of >30% during evaluation period of 50 years.
With present knowledge, this species seems to be a mainly North European one, almost confined to Fennoscandia-W Russia. The main populations are in the northern boreal regions. The species is recently reported also from the caledonian pine forests of Scotland (one find, confirmed by molecular identification. Ocurrence in the coniferous regions of C Europe is not well documented, but one record is indicated from Austria, and one from Slovenia.
Currently know from ca. 200 localities. In Norway the species is recorded from 32 localities, half of them at Pasvik, Finnmark, NE Norway. In Sweden, the species is known from 120 localities (mainly in N Sweden), probably with a similar ocurence in Finland. It’s known one site in Russia, Leningrad region, and could have a wider distribution in the sandy pine forests also in this region, being adjacent to the core area of Sweden-Finland. The real number may be 10x higher and are estimated to approx. 2.000 inferring maximum 40.000 individuals. The species has (only) small subpopulations and is heavily fragmented.
The species and its habitat (old-growth, sandy pine forests) are probably decreasing with more than 30% in 3 generations (50y). Forest where it occurs are primarily threatened by clearcutting and possibly it is also negatively affected by nitrogen fertilization of forests. There is furthermore seen a habitat loss of sandy pine forests in many areas due to urbanization, road constructions, etc. The species seems to lack in younger forests after clearcutting, probably due to the lack of downed logs which the species needs as attachment of the basidiocarps. It may also be due to its slow population dynamics, surviving natural disturbances like forest fires on surviving, old pines. Historically, boreal forest fires commonly has been low-intense with a high degree of tree survival, and hence with a high likeliness for mycelia of ectomycorrhizal fungi to be very old.
Hydnellum gracilipes forms mycorrhiza with Scots pine (Pinus sylvestris), in dry, preferentially lichen-dominated, richer, continental sandy pine forests, sometimes also in richer low-herb(-calcareous) pine forests, and in rocky pine sites with shallow soils, (possibly with small deposits of sandy moraine). The species furthermore regularly occur in old-growth to pristine, often forest-fire influenced forest sites. The mycelia of the fungus is considered to potentially be as old as the pines, or older. Probably, the mycelia of the fungus survive forest fires if the Scots pine trees they are associated with do.
It is primarily threatened by clearcutting of old-growth pine forests, nitrogen fertilization of forests, and measures to prevent forest fires.
To prevent decline and fragmentation of the old-growth, dead- wood-rich sandy pine forests with natural dynamics it is important to set aside Scots pine forest reserves, preferentially larger, continuous areas, in regions where the species have good populations. In these forests, natural or prescribed burning should be considered to maintain desired forest dynamics.
Since the species is rather well hidden (under logs) and little known until recently (almost all Fennoscandian finds are after 2000), more mapping/monitoring is needed, especially in new potential areas such as northern boreal sandy pine forests in Russia. The species supposed slow population dynamics, with probably very old genets, and re-vitalization by forests fires should also be studied/documented further.
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.
Ainsworth AM, Parfitt D, Rogers HJ, Boddy L, 2009. Cryptic taxa within European species of Hydnellum and Phellodon revealed by combined molecular and morphological analysis. Fungal Ecol. 3(2): 65-80.
Köljalg U, Renvall P, 2000. Hydnellum gracilipes - a link between stipitate and resupinate Hymenomycetes. Karstenia 40: 71-77.
Kotiranta H, Saarenoksa R, Kytövuori I, 2009. Aphyllophoroid fungi of Finland. A check-list with ecology, distribution, and threat categories. Norrlinia 19: 223 pp.
Kuoljok S, 2003. Smalfotad taggsvamp - en doldis. Jordstjärnan 24(2): 4-9.
Kuoljok S, 2005. Artfaktablad: Hydnellum gracilipes, smalfotad taggsvamp. ArtDatabanken, SLU.