Hygrophorus marzuolus is a, edible ectomycorrhizal species mainly of Abies, fruiting in spring. 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.

Temperate Europe (around the Alps and the Carpathes) and mountainous zones in North Africa. Mainly within the area of occurence of Abies alba.

Judging from distribution maps Baden-Württemberg counts about 70 sites (Krieglsteiner 2001), Switzerland about 200 (http://www.swissfungi.ch)  and Austria 120 (http://austria.mykodata.net). In Italy it is recorded from 13 regions (Onofri 2005).The database from Switzerland suggests losses in the past 60 years.
The fungus nearly exclusively occurs in natural and near-natural forests (seldom in plantations).
In the past the species was sold on markets in Austria, France, Germany, Italy, and Switzerland (nowadays this is prohibited)

The fungus mainly forms ectomycorrhiza with coniferous trees of the family Pinaceae, most often with Abies (alba, borisii-regis [Macedonia]) 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, and Qu. petraea. 
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 (?). 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 (e.g Bernadzki,  E. 1983) in Europe. Its reaction to climate change and its prospects are controversly debated (Hanewinkel et al 2011, Tinner et al 2013)
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)

Onofri, S. (ed). 2005. Checklist of Italian fungi- Basidiomycetes. O.P.T.I.M.A. 380 p.
Krieglsteiner, G.J (Hrg.) 2001. Die Grosspilze Baden-Württembergs. Band 3. Ulmer Verlag 634 p
Kraft M.-M.(1958) Sur la répartition d’Hygrophorus marzuolus (Fr.) Bres. Ber. Schweiz. bot. Ges. / Bull. Soc. bot. Suisse 68: 254-288.
Kraft M.-M.(1959) Sur la répartition d’Hygrophorus marzuolus (Fr.) Bres. (note complémentaire). Ber. Schweiz. bot. Ges. / Bull. Soc. bot. Suisse 69: 246-248.
Razaq A. & Shahzad S. (2005) Hygrophorus marzuolus, a new report from Pakistan. Pak. J. Bot. 37 (4): 1031-1032.
Bernadzki,  E.  1983.The dying of fir within its natural range. In: Biatobok S. (ed.), Jodla pospolita Abies alba Mill., pp.  493-501, PWN,  Warszawa-Poznafi (P)
Willy Tinner, Daniele Colombaroli, Oliver Heiri, Paul D. Henne, Marco Steinacher, Johanna Untenecker, Elisa Vescovi, Judy R. M. Allen, Gabriele Carraro, Marco Conedera, Fortunat Joos, André F. Lotter, Jürg Luterbacher, Stéphanie Samartin, and Verushka Valsecchi 2013. The past ecology of Abies alba provides new perspectives on future responses of silver fir forests to global warming. Ecological Monographs 83:419–439.