Assessment Notes

Justification

Hygrocybe helobia belongs to the European waxcap assemblage whose members are globally Red Listed based on the declining area/quality of their grassland habitat. This assemblage is declining across Europe due to changes in land use (agricultural intensification and decline of traditional farming practices) and increasing use of fertilizers and pesticides. Declines in area and quality of available habitat has approached 30% over the last 50 years (three generations); the decline in population size over this time has exceeded 30% in continental Europe and been less in so northern countries. This decline in habitat is expected to continue over the next 50 years. Overall, the population size is expected to be declining at a rate approaching 30% over three generations The population size probably exceeds 20,000 mature individuals. The species approaches the threshold for consideration as threatened under criterion A, and so is assessed as Near Threatened A2ce+3ce+4ce.

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Taxonomic notes

This taxon is believed to be confused with Hygrocybe miniata in Norway and Sweden and probably elsewhere.

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Geographic range

Hygrocybe helobia is a relatively distinctive species that is widespread in Europe (Boertmann 2010, GBIF 2024). Although there is no ex-type sequence yet available, the sequenced specimens include one determined by the taxon's author E.J.M. Arnolds (Lodge et al. 2014, Dentinger et al. unpubl.). The eastern boundary of the species is, as is the case for all members of this assemblage, unclear because of lack of data. It is present in the European parts of Russia (incomplete map).

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Population and Trends

The population size probably exceeds 20,000 mature individuals but exact figures are unknown. GBIF (2024) lists more than 2,500 records. The population is assessed as decreasing in Europe, less so in the north and more in the south, caused by a cessation of small scale farming and traditional methods of grassland management. The eastern boundary of the range and the population status is, as is the case for all members of this assemblage, unclear because of a lack of data.

According to the Food and Agriculture Organization of the United Nations (FAO), the area of grasslands in the EU declined by 12.8% over 13 years (1990-2003); only a few Member States managed to avoid this trend (Food and Agricultural Organisation of the United Nations 2006). Based on this, the habitat decline is inferred to be relatively rapid and ongoing. This species has also been recorded from wetter sites including Sphagnum bogs (Arnolds 1990), but is nonetheless a characteristic "waxcap grassland" species. With the species relatively secure further north (nationally Red List assessed as Least Concern (LC) in the Denmark, Finland, Norway and Sweden; Hyvärinen et al. 2019, SLU Artdatabanken 2020, Artsdatabanken 2021, Moeslund et al. 2023), at the overall European level, the population decline is suspected to approach 30% over 50 years (three generations), being higher in continental Europe (i.e. closer to the c. 1% loss per year for FAO 2006) and lower in northern Europe.

Population Trend: Decreasing

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Habitat and Ecology

Hygrocybe helobia is an indicator of mycologically rich but nutrient-poor, semi-natural grassland (a member of the waxcap grassland assemblage). This habitat, which may be of low conservation concern for its plant and animal diversity, is rapidly disappearing worldwide due to changes in land use (intensification of farming practice, eutrophication and increased use of fertilizers and pesticides). Waxcaps are currently regarded as forming a biotrophic relationship with plants but the details remain unclear. Fruiting populations of waxcaps are nitrogen sensitive and dependent on a regime of grazing or mowing without applications of fertilizer or pesticide. The waxcap grassland assemblage is characterised by a large diversity of other fungal genera (including Entoloma, clavarioid taxa and geoglossoid taxa) that have similar nutrient and management requirements. Addition of fertilizers or cessation of grazing/mowing management is rapidly detrimental to fruiting community diversity. This species has also been recorded from wetter sites including Sphagnum bogs (Arnolds 1990).

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Threats

As a species dependent on semi-natural grasslands, Hygrocybe helobia is threatened by habitat loss and degradation due to a decrease in small scale, low intensity farming. The main reasons for declines involve land that is no longer farmed or, if still in the farming system, is subjected to ploughing, reseeding, fertiliser application (mainly of phosphorus and nitrogen), pesticides, reduced grazing intensity and eutrophication. According to NATURA 2000 reports (Calaciura and Spinelli 2008), grassland habitats are steadily decreasing, mainly due to abandonment or change in land use. According to the Food and Agriculture Organization of the United Nations (FAO), the area of grasslands in the EU declined by 12.8% from 1990 to 2003; only a few Member States managed to avoid this trend (Food and Agricultural Organisation of the United Nations 2006).

Pressure caused by land use changes on grassland habitats is steadily increasing. Some 60% of newly afforested areas in the EU formerly were used as permanent/seasonal grazing land or hay-production in natural meadows. More than 75% of the grassland habitats in the EU are in an unfavourable conservation status, according to draft data provided by Member States under Article 17 of the Habitats Directive.

According to the European Environment Agency (2015), natural and semi-natural grasslands have undergone a major decline in recent decades. Grasslands have one of the lowest proportions (11%) of favourable condition assessments and one of the highest proportions of decreasing assessments of all the terrestrial ecosystems considered. About 49 % of EU assessments for the 45 grassland habitat types of Community interest are "unfavourable-bad". Grassland butterflies, for example, are declining severely and there is no sign of level-ling off (European Environment Agency 2024). Accordingly, Janssen et al. (2016) reported that 53 % of the grassland habitats in Europe are threatened to some degree (the second most threatened habitat type after “mires and bogs”).

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Conservation Actions

Hygrocybe helobia is nationally Red List assessed as Least Concern (LC) in the Nordic countries (Denmark, Finland, Norway and Sweden; Hyvärinen et al. 2019, SLU Artdatabanken 2020, Artsdatabanken 2021, Moeslund et al. 2023). In the continental European countries, it is nationally assessed as Vulnerable in the Netherlands, Austria and Switzerland (Senn-Irlet et al. 2007, Arnolds and Veerkamp 2008, Dämon and Krisai-Greilhuber 2017) and nationally listed as hazard category of unknown extent but strongly declining in Germany (Dämmrich et al. 2016).

Site protection and management of habitats are both very important conservation actions for this species. Grazing, at least before the onset of the fruiting season, is of fundamental importance. On sites where cattle would cause soil erosion (e.g. sloping ground, thin soils), sheep are the preferred grazing animal. Mowing, with collection of ‘arisings’, can substitute for grazing. Further ecological research is needed to clarify resource relations of waxcaps, population biology and full distribution range.

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Use and Trade

No use or trade is known.

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Source and Citation

Ainsworth, A.M. 2025. Hygrocybe helobia. The IUCN Red List of Threatened Species 2025: e.T147967887A147967929. Accessed on 22 November 2025.

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• Country occurrence