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The purpose of the study is to find which habitats within Central Europe support the persistence of isolated populations of spider species of both boreal and Alpine origins. Twenty-five species exhibited disjunctive distributions with their main sub-area in the tundra or boreal forest, and isolated sub-areas in the temperate zone of Central Europe. Six species exhibited disjunctive distributions with their main sub-area in the Alps, and isolated sub-areas in the temperate zone in Central Europe. Only (approximately) one-third of the species of boreal origin have the same habitat, as in the boreal zone. Twothirds of the species inhabit different habitats, or have narrowed their ecological valency. Screes play an important role in the survival of these isolated populations of species of boreal origin in the temperate zone, together with mountain summits, mountain forests, and peat bogs. Extensive complexes of sandstone rocks also enables the survival of isolated populations of species of boreal origin.
The thermal regime of a phonolite scree slope on Klíč Mt., North Bohemia, Czech Republic, was monitored by miniature data loggers. The spiders were collected throughout the entire scree field area and on the adjacent cliff. In 2005 and 2006, the mean internal temperatures at the lower margins of the scree slope were 0.1 and 0.5°C, whereas the mean external ambient temperatures were 6.8 and 7.2°C, respectively. The difference, therefore, is 6.7°C. The long-term cooling of the basal portions, along with the winter heating of the central and upper parts of the scree, are the most specific microclimatic phenomena. The boreomontane species inhabit the extremely cold vents at the lower margins of the scree slope. Species of alpine origin inhabit the middle portions of the scree slope. Six thermophilous species inhabit the sun-exposed rock margins of Klíč Mt., which is nearly at the uppermost limit of their vertical distribution in the Czech Republic.
Rocks have been overlooked as subjects for ecological study. However, the system of narrow and deep vertical spaces (gorges, crevices, abysses) in sandstone rocks supports a highly diverse mosaic of habitats. The patterns of air temperatures and the assemblages of arthropods were studied along the environmental gradient in the Poseidon Sandstone Labyrinth within the Adršpašsko-Teplické Skály National Nature Reserve, NE Bohemia, Czech Republic. The labyrinth, developed in Cretaceous sandsones at an altitude of about 600 m, is approximately 740 m long and 550 m wide. It consists of a broken, interconnected network of deep vertical crevices, crevice caves, and talus caves in extensive block accumulations. The total length of the human-accessible underground spaces is estimated to be at least 27 km, the vertical range is 105 m. The annual course of air temperature was monitored on the sun-exposed upper rock margin (max. 26.5°C, min. –7.3°C, mean 6.1°C), as well as in the cold and dark crevice cave (max. 9.6°C, min. –1.9°C, mean 3.7°C). Due to the climatic inversion in the deep vertical spaces, mountain bryophytes and vascular plants occur here. A total of 2285 arthropods belonging to eight taxonomic groups were evaluated; spiders and beetles were the most numerous. We registered 304 species, which colonize the totality of habitats in the labyrinth: cold bottom parts, dark caves, shady rock walls, as well as the sun-exposed upper rock margins. The cold parts of the labyrinth harbour populations of sixteen species of mountain arthropods (beetles, spiders and a harvestman) and five species of arthropods with distributions in tundra or boreal forests, and similar disjunctive habitats in the temperate zone in central Europe (spiders and a mite). The first record of the Arctic predatory mite Rhagidia gelida in central Europe was in the Poseidon Labyrinth in 1986; this species proved to be a bio-indicator of the long-lasting periglacial microclimate in central Europe. Prior to discovery of the spider Sisicus apertus in the Poseidon Labyrinth, it had been recorded in central Europe in the Alps and in the High Tatra Mountains at altitudes of 1150 to 2300 m. At the present time, we consider the Poseidon Sandstone Labyrinth to be a paleorefugium of cold-adapted arthropods.
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