Hygrocybe splendidissima is a species of seminatural grassland in Europe. The largest populations are found in lowlands near the coasts. The habitat is strongly declining due to changing agricultural practices, development projects and pollution. We assume a total habitat loss of at least 30% over the last 50 years (approximately three generations: one generation is assumed to be about 17 years). 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. GBIF lists more than 2600 occurrences. The species is assumed to have a population of more than 20000 mature individuals. At a global scale the population decline is assumed to be on the average 30-50% in 50 years (past, present and future). The species meets the threshold for VU (A2c+3c+4c).
Hygrocybe splendidissima belongs in Hygrocybe s.str. close to H. coccinea and H. punicea, based on molecular methods (Lodge et al. 2013). The type is from England. It can be confused with H. coccinea, but has e.g. +/-free lamellae. The taxonomic status of GBIF occurences in the west coast of USA is uncertain; this could be another taxon and will not be further treated here.
This is a species of old seminatural grasslands, a habitat which is strongly declining due to changing agricultural practices, development projects and pollution. There is also a serious decrease in quality of the remaining habitats. The largest population seems to be in coastal/lowland parts of NW Europe, in areas with partly rapid changes in land use.
The largest populations are in NW Europe (especially UK, Germany, Sweden, Denmark, Norway) and with scattered occurences in the rest of western and central Europe. Further known from France, Belgium, Netherlands, Germany, Poland, Switzerland, Austria, Czechia, Slovakia, Estland etc. The absence from Finland and most of eastern Europe, and the higher frequency in western Norway, southern Sweden, Denmark, Germany and UK, suggest a coastal distribution which could be caused by frost intolerance. The eastern boundary of distribution is less clear due to lack of data. Confusion with H. coccinea and other relatives in some countries can not be excluded.
GBIF (2019) lists ca. 2600 occurrences from Europe. The total population probably exceeds 20 000 mature individuals but is decreasing in all known countries of occurence, caused by disappearance of small scale farming and traditional ways of grassland management. 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 grasslands habitats are in an unfavourable conservation status (http://ec.europa. eu/environment/nature/knowledge/ rep_habitats/index_en.htm#csa). We assume a total habitat loss of 30-50% over the last 50 years. This trend is expected to continue in the future.
Population Trend: Decreasing
Hygrocybe splendidissima is an indicator of mycologically rich but nutrient-poor, semi-natural grassland (a member of the waxcap grassland assemblage), often on acid soil. This habitat, which may be of low conservation concern for its plant and animal diversity, is rapidly disappearing due to changes in land use (see Threats). It is most often found in lowland/coastal habitats, e.g. typical along the western coast of Norway. In Norway, most localities are seminatural grasslands or grassy/mossy spots in coastal Calluna heath (N=462; 91,6% in seminatural grasslands, only 5,3% in forests; Jordal et al. 2016), and similar patterns are found in other countries. Waxcaps are currently regarded as forming a biotrophic relationship with plants but the details remain unclear (Halbwachs et al. 2018). The fruit bodies are short-lived (weeks), but the mycel is suspected to be longlived; >50-100 years.
Habitat destruction and abandoning are the main threats to seminatural grasslands. The most important process is probably withgrowing due to ceased grazing/mowing of old seminatural grasslands as part of intensification of agriculture. Further modern cultivation methods like use of fertilizers, pesticides and plowing. Also some places changed land use with the construction of roads, industrial areas, settlements etc. Decline is expected to continue, as the areas of seminatural grasslands are of little economic importance in modern agriculture. Most waxcap grasslands are among types redlisted as VU, EN or CR in the EU red list of habitats (Jansen et al. 2016). The quality of habitats is also decreasing. More than 75% of the grasslands habitats in EU are in an unfavourable conservation status, according to draft data provided by Member States under Article 17 of the Habitats Directive.
Site protection and management of habitats are very important conservation actions. The habitats should be protected against destruction due to intensification of agriculture or development plans. The maintaining of seminatural grasslands demands yearly grazing or mowing. 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 areas of agricultural areas, and should be extended to larger areas than today. The species is included in a sweedish action plan also comprising two other grassland species (Jordal 2011).
Further ecological research isneeded to clarify the nutrient strategy of waxcaps. Management plans are needed. Habitat trends should be monitored.
The species is not known to be used.
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