Molecular data has confirmed the status of this species within Geastrum section Campestria. (Zamora et al 2014).
Geastrum campestre var. pouzarii (V.J. Stanek) Calonge (1998)
Geastrum pedicellatum var. pouzarii (V.J. Stanek Dörfelt) (1985)
Geastrum pouzarii is a small saprotrophic fungus mainly occurring in dry, steep grassland slope habitats. Although it was not described until 1954, it is a well-known species, for several years considered to be endemic to Central Europe, where it seems to have its main occurrences (< 15 locations in the Czech Republic, one location in Switzerland). It is further known from 3 locations in South Russia (Rostov region). Lately a few records from Spain (1 location), Russian (Altai) and Mexico (Baja California: 4 locations) have been added, indicating that the species might have a world-wide distribution, although being extremely rare. In Central Europe it occurs in open patches in mosaic habitats in deciduous woodlands on steep steppic grassland slopes (southern exposure) on mostly basic soil. The surrounding vegetation is distinctly thermophilic. A potential decline in population can be expected due to habitat changes (overgrowth) caused by a decrease in grazing management and/or exploitation of habitats (limestone quarries, roads, buildings etc), clear-cutting etc.
Global Red List assessment: DD since molecular data to confirm conspecificity for American records are missing. European assessment: VU C2a(i).
The species has a very small population globally and a decline in Europe is expected. For North America more information is needed.
Need of more information: Status and distribution in North America as well as eastwards on the Eurasian continent. The conspecificity with the European G. pouzarii of the Mexican records needs to be confirmed with molecular methods.
Central Europe (Czech Republic, Switzerland), Southwestern Europe (Spain), Russia (Rostov region and Altay) and North America (Mexico, Baja California).
The small population of a well-known and easily recognizable species indicates that it is a rare species. It has been well searched for by Central European mycologists. It is however difficult to estimate the current status of the population but a decrease in grazing and exploitation oh habitats in Central Europe is a potential future threat to its habitats.
Population Trend: Uncertain
Geastrum pouzarii is a saprotrophic fungus adapted to dry and warm conditions. All known Central European occurrences are situated on dry slopes with thermophilous vegetation. It seems to prefer open to semi-open patches in the mosaic landscape characterizing these slopes. The Spanish record is from under an old Juniperus thurifera in a dry steppe habitat. The locations in both Central Europe and in Spain are very “old habitats” with a long continuity of the present land management (grazing). The Russian records are from grazed sandy grassland. Although one of the Russian findings were close to a farm, there are no records of Geastrum pouzarii from anthropogenous habitats in Central Europe (eg parks and gardens, road verges, farm yards), as is the case for a number of other earthstar species. In Sonora (Baja California, Mexico) it was recorded under arid to semi-arid conditions in microphyllous desert scrub, tropical thorn forest and tropical deciduous woodland. Unlike most other earthstars, G. pouzarii is reported to form fruiting bodies in early spring (Europe).
The small population of Geastrum pouzarii makes it vulnerable to random extinction of individual occurrences which dramatically can decrease its chances to survival and reproduction. Some of the Czech occurrences are protected as nature reserves, but the species is nevertheless considered threatened in the Czech Republic (EN). The main threat to the habitat in which Geastrum pouzarii is found seems to be overgrowth due to a decline in grazing management. The species prefers open to semi-open habitats in exposed and sloping patches in a mosaic landscape, maintaining its open/semi-open character chiefly by grazing animals. A secondary threat to its habitats seems to be exploitation by road constructions, buildings as well as limestone quarry activities. The latter seems to have destroyed several potential localities for G. pouzarii in Central Europe.
Several of the occurrences in the Czech Republic are situated in nature reserves and the Mexican records have all been made in priority regions for conservation of biodiversity. All occurrences of Geastrum pouzarii should be under some kind of protection ensuring a traditional management. In known localities annual monitoring should be organized to get a clearer picture of the present population status and changes over time.
The conspecificity of the Mexican samples with the European Geastrum pouzarii should be investigated with molecular methods. The species should be searched for in steppe slope habitats in the Czech Republic, Slovakia, Switzerland, Germany, Hungary, the Balkan countries etc.
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