R-L categories correct, but text here does not match final assessment. Updated version will be published in IUCN´s Red List June or Nov 2019.
Hygrophorus marzuolus is edible ectomycorrhizal palearcitic species mainly of Abies, Pinus and Fagus, fruiting in spring. Despite the fact that it occurs from Spain through Alps and carpathians to Greece and even Siberia, center of its occurrence is continental Europe. It has been recorded regularly only from Spain, Alpine countries, Czech Republic, Slovakia, Hungary and Slovenia. Only isolated single and historical records are reported from bordering regions.
Considerable decrease has been noted in most parts of the area of occupancy in the last 40 years, probably due to nitrogen deposition and old forests decline, by extensive management. The population even in the most populated areas if fragmented, restricted to old forests of special ecology. Number of mature individuals probably do not exceed 10 000 and estimated continuing decline is 10 % in 10 years or 3 generations.
This species meets the threshold for VU C1.
In GBIF (2019) North American collections are treated as one species. This is probably not true, because of the different ecology of American soecies. It has been recorded from June to August at altitudes 2000 to 4000 m. Further taxonomic research based on the comparison of DNA sequences is needed.
Hygrophorus marzuolus is a, edible ectomycorrhizal species mainly of Abies, fruiting in spring. Most records come from continental Europe, where it occurs fragmentaily in mountainous areas. Considerable decrease has been noted in most parts of the area of occupancy in the last 40 years, probably due to nitrogen deposition and fir decline.
Hygrophorus marzuolus is distributed in the temperate Europe around the Pyrenees, Alps and the Carpathes. Single records come from bordering sites at Greece (2), Russia (Caucassus, Krasnojarsk, Tomsk), Pakistan (1) and Morocco (1). Not known from Scandinavia and United Kingdom. Mainly within the area of occurence of Abies alba. In southern areas and central Europe also with deciduous trees (Castanea, Fagus). Most of the records come from Slovenia (200) and Switzerland (200) as a result of broad mapping projects.
The population of H.marzuolus shows slight but significant declite since 1960. Most of the records come from 1980 - 1990, recent records are quite scare. The database from Switzerland suggests losses in the past 60 years. The mushroom is represented only fragmentarily in Europe and has its main spreading in the alps and their foothills between 200 to 2000 a.s.l. It is generally considered to be in decline.
It is probably much overlooked as it appears outside the main season and it is difficult to spot in the forest.
The species is red listed in Austria, Czech Republic, France, Germany, Hungary, Macedonia (preliminary list), Montenegro, Serbia, and Slovakia. It is protected by law in Croatia, Germany, Serbia, and Slovakia. The species is locally protected or picking is restricted in certain regions of Italy (Onofri 2005)
Population Trend: Decreasing
Hygrophorus marzuolus mainly forms ectomycorrhiza with coniferous trees of the family Pinaceae, most often with Abies (alba, borisii-regis ) and Picea, but also with Pinus (mugo incl. uncinata, nigra, sylvestris) and Pseudotsuga (France). Only relatively seldom the fungus was found in symbiosis with Fagaceae, especially Fagus sylvatica, in Southern Europe moreover Castanea sativa, Quercus cerris, Q. suber and Q. petraea. The fungus nearly exclusively occurs in natural or near-natural forests and only rarely in plantations. It has been recorded on calcareus as well as acidic and sandy soils.
In Europe friuting early in the spring (March-April) in altitudes up to 2000 m.
Some of the Natura 2000 habitats in Europe:
Luzulo-Fagetum beech forests (code 9110),
Asperulo-Fagetum beech forests (code 9130)
Medio-European limestone beech forests of the Cephalanthero-Fagion (code 9150)
Galio-Carpinetum oak-hornbeam forests (code 9170)
Acidophilous Picea forests of the montane to alpine levels (code 9410)
In the European scale the fungus is vulnerable due to the loss of the suitable habitat, which is naturally grown coniferous and mixed forests . Sites are mainly threatened by silvicultural intensification (e.g. clear felling, planting of allochthonous trees, fertilization), but also by strong acidification due to air pollution. Silver fir (Abies alba) showed a strong dieback in the 1980s in its range of occurrence in Europe.
Taxonomic research is needed to clarify the relationship within European and North American pooulations.
Hygrophorus marzuolus is an appreciated edible mushroom. In the past, it was sold on markets in Austria, France, Germany, Italy, and Switzerland (nowadays this is prohibited).
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