The taxonomic status of collections from North America (GBIF 2021) and the Russian Far East (T. Svetasjeva pers. comm.) is uncertain, and they are here regarded as probably related species.

Hygrocybe aurantiosplendens is a typical representative of the rich funga of old, unimproved grasslands, a habitat type that is decreasing rapidly in all of Europe. It occasionally grows also in scrub and calcareous forests on moist to dry, base-rich soils. The species is very striking by its size and bright orange basidiocarps and is usually well distinguishable from related species. It is only known from Europe, and is widespread, but rare to very rare everywhere (Boertmann 2010) and decreasing. H. aurantiosplendens is listed as Near Threathened or Threatened in many national Red Lists.

Over the distribution range we assume a total habitat and population decline of 30-49% over the past 50 years (approximately three generations). Habitat quality has also become impaired and the decline in population size over this time could be even higher. This decline in habitat is ongoing and expected to continue over the next 50 years. The species meets the thresholds for Vulnerable under criteria A2ce+3ce+4ce.

Hygrocybe aurantiosplendens is widely distributed in Europe. The species is most frequent in northern Europe (Scandinavia, Great Britain) and more rare in the south (here often in mountain regions). Data under this name from from North America (GBIF 2021) and the Russian Far East (T. Svetasjeva pers. comm.) are regarded as uncertain.

GBIF (2024) lists ca 1,600 occurrences of Hygrocybe aurantiosplendens from Europe. It is widespread, but rare to very rare everywhere (Boertmann 2010) and decreasing. The largest subpopulations seem to be in Scandinavia and Great Britain. The total number of individuals is unknown but probably exceeds 20,000 mature individuals.

Griffith et al. (2013) estimated a habitat loss of 90% over the last 75 years for the CHEG-fungi (grassland fungi of the groups Clavariaceae, Hygrocybe s.l., Entoloma and Geoglossaceae) as a whole in Western Europe (i.e. loss in seminatural grasslands, based on available information). According to the Food and Agriculture Organization of the United Nations (FAO 2006), the area of grasslands in the EU declined by 12.8% over 13 years (1990-2003). The habitat quality of seminatural grasslands is also declining, strengthening the population decline. More than 75% of the grassland habitats are in an unfavourable conservation status (EEA 2021). We assume a total habitat loss of 30-49% over the last 50 years (three generations). In combination with the reduction in habitat quality, this is conservatively assumed to equate to a population loss of 30-49% over the last 50 years (three generations). This trend is is ongoing and expected to continue in the future. The decline is reflected in the position of H. aurantiosplendens on many national Red Lists, e.g. Endangered in Denmark (Moeslund et al. 2023), Finland (Hyvärinen et al. 2019), Poland (Mirek et al. 2006); Vulnerable in Austria (Dämon and Krisai-Greilhuber 2017) and Germany (Dämmrich et al. 2016); Near Threatened in the Netherlands (Arnolds and Veerkamp 2008), Norway (Artsdatabanken 2021), Sweden (SLU Artdatabanken 2020).

Hygrocybe aurantiosplendens is a characteristic species of old, unimproved, low productive grasslands on loamy, weakly acid to basic, often calcareous soils. It occurs from sea level up to the alpine zone (2,500 m in the Alps), but is not found in the alpine zone in Norway. It occasionally grows also in scrub and calcareous forests on moist to dry, base-rich soils. In Norway, about 20% of all records are from calcareous forests, the rest mainly from open grasslands (Jordal et al. 2016). Like other waxcaps, the species probably lives in biotrophic association with herbaceous plants, but details are unknown (Halbwachs et al. 2018).

Threats to this species are from grassland improvement (fertiliser application and soil disturbance) for agro-industry farming, the abandoning of low productive grasslands, and conversion to forest plantations on poor grassland sites. Moreover the species is vulnerable to acidification and nitrogen deposition (Arnolds 2015).

No use or trade is known.

The most important action will be: the conservation of sites with rich subpopulations of Hygrocybe aurantiosplendens as nature reserves; continuation of traditional management: mowing and removal of sward and/or grazing in low densities without fertiliser application. If grazing by heavy animals destroys part of the soil, light animals like sheep should be recommended. Habitat conservation by governmental support to traditional agricultural practices is most important, this exists in many countries to maintain extensive agricultural areas, and should be extended to larger areas than today. The species is a representative of a rich funga with many more rare and threatened species; therefore its protection will be beneficial to many more threatened fungi (Boertmann 2010, Arnolds 2015). There is a conservation action plan for this species in Sweden (Jordal 2011). Additionally, more detailed research on habitat requirements of H. aurantiosplendens would be useful, and its habitats should be monitored.