Assessment Notes

Justification

Hygrocybe swanetica is a rare and easily recognisable colourful waxcap that grows on large logs of Abies, an unusual habitat for waxcaps. It is only known from Russia (Western Caucasus and Eastern Asia) and Georgia, and is restricted to old-growth or virgin forests formed by, or mixed with Abies. The number of known localities is 11. Considering unrecorded localities, the total number of localities is estimated to be 50 (surely not exceeding a total of 100 localities), corresponding to a number of mature individuals not in between 1,000 and 2,000, with less than 500 in the largest subpopulation. Most occurrences are located within protected areas of natural forest. It has not been found in managed forests. Ongoing clearcutting of old Abies forests within its geographic area is a threat and it is inferred to cause an ongoing decline in the population size. This species qualifies for listing as Vulnerable C2a(i).

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Geographic range

Recorded only from montane areas in Georgia (Central Caucasus) and Russia: Caucasus (Western and Central) and Russian Far East (southern Sakhalin, middle Sikhote-Alin, Zeya river basin, Ussuriysky district). The known distribution is two disjointed areas - Georgian and Russian Caucasus, and Russian Far East - with no records between them.

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Population and Trends

In total, Hygrocybe swanetica is known from about 10 localities in Russia and one locality in Georgia (the type locality in Swaneti). It is recorded almost every year in the basin of Belaya river (Russian Western Caucasus, Caucasian State reserve), in other localities the periodicity of fruiting is not known. One of its recorded localities (outside protected areas) has most probably been destroyed due to clearcutting. The total number of localities (including the unknown ones) is estimated to be 50 (not exceeding 100). Typically, it is recorded from one log per site. The number of mature individuals (two mature individuals per functional individual, i.e. per trunk or log, c.f. Dahlberg and Mueller 2011) is estimated to be in between 1,000-2,000 mature individual (as usually only one log of the required size and age is found in each locality), the number of mature individual in the largest subpopulation is not above 500. Habitat decline is ongoing due to clear-cutting of old-growth forests of Abies and decreasing the amount of large logs, as well as disturbance of suitable habitats by road construction.

Population Trend: decreasing

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Habitat and Ecology

Hygrocybe swanetica is one of the few Hygrocybe species growing in rotten dead wood. It grows on large logs, up to 2 m in diameter, stumps, and pieces of scattered wood of Abies, sometimes also in soil containing wooden remains. It was found on Abies nordmanniana in the Caucasus and A. holophylla in the Far East. It appears to be rare at all known sites, typically with one record per site. Most of the collections have been made in old-growth or virgin mesophilic forest formed by Abies and mixed forests with Abies. In the Caucasus it was found only in forests with tertiary relict plant species (Rhododendron ponticum, Helix colchica etc.) (Red Data Books 2012, 2017). Most known localities are situated inside protected areas with different status of protection. It has not been recorded in young or managed forests.

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Threats

The main threat is the decline of old-growth forests (clearcutting) and decreasing of large logs, as well as disturbance of suitable habitats by road construction and other human activities. For example, some areas of valuable old forest were cut down during preparations for the Olympic Games in Sochi.

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Conservation Actions

It is protected at the regional level in Russia, in three administrative units (Krasnodar Krai, Adygei Republic, Karachay-Cherkess Republic), and preserved in three state nature reserves. It is recommended to be included in the new edition of the Red Data Book of the Russian Federation as EN С2a(i). In Georgia it is not protected. All the known sites should be protected. The species needs continued protection of all habitats - old-growth Abies forests. Searching for new localities in suitable habitats is needed. Research on the species' life history and ecology and better knowledge on its geographic distribution is required. Also DNA analysis is desirable to confirm this as a separate species.

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Use and Trade

The species is not used.

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Source and Citation

Kiyashko, A. & Svetasheva, T. 2019. Hygrocybe swanetica. The IUCN Red List of Threatened Species 2019: e.T75115985A75116092. https://dx.doi.org/10.2305/IUCN.UK.2019-2.RLTS.T75115985A75116092.en .Accessed on 3 February 2024

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• Country occurrence