Molluscs of the Krkonoše Mts. (Czech Republic)

The Krkonoše Mts. (=Giant Mts.) are the highest mountain range of Bohemia and their peak Sněžka Mt. with its altitude of 1602 m is also the highest point of the whole Sudetes. The Krkonoše Mts. consist of two contrasting lithologies – the larger southern part is built of Proterozoic mica schists, gneisses and phillites which are fringed by Palaeozoic low-grade metamorphosed schists, phillites and limestones; the northern part of the range is dominated by acidic granites. A few Tertiary basalt intrusions of minor extent occur within a crystalline complex. General relief pattern of the Krkonoše Mts. comprises large summit plateaus at elevations of 1300–1500 m, dissected by deeply incised glacial cirques and troughs as well as by steep-side erosional valleys. Glacial landforms are characterised by fresh outcrops of bedrock, whereas slopes of cool humid climate that becomes progressively important with increasing elevation. Acidic cambisols dominate the submontane belt (400–800 m) grading into spodo-dystric cambisols and ferro-humic podsols in the mountain and supramountain belt (800–1200 m). There are alpine soils (acidic ranker, lithosol) on flat summit plateau and extensive peat bogs, which have developed since the onset of postglacial Climatic Optimum to the Recent. At present, the whole range is dominated by Norway spruce that is native to the supramountain belt and to mountain beech-spruce forests of the mountain belt. The submountain belt was formerly characterised by mixed woodland with a high proportion of deciduous trees, which have been, however, replaced by spruce plantations since the 18th century. In the eastern part of Krkonoše primeval forests have been already largely devastated by intensive exploitation during the14 th and 15th centuries. Malacologica Bohemoslovaca (2008), 7: 55–69 ISSN 1336-6939


Introduction
The Krkonoše Mts. (=Giant Mts.) are the highest mountain range of Bohemia and their peak Sněžka Mt. with its altitude of 1602 m is also the highest point of the whole Sudetes. The Krkonoše Mts. consist of two contrasting lithologies -the larger southern part is built of Proterozoic mica schists, gneisses and phillites which are fringed by Palaeozoic low-grade metamorphosed schists, phillites and limestones; the northern part of the range is dominated by acidic granites. A few Tertiary basalt intrusions of minor extent occur within a crystalline complex. General relief pattern of the Krkonoše Mts. comprises large summit plateaus at elevations of 1300-1500 m, dissected by deeply incised glacial cirques and troughs as well as by steep-side erosional valleys. Glacial landforms are characterised by fresh outcrops of bedrock, whereas slopes of cool humid climate that becomes progressively important with increasing elevation. Acidic cambisols dominate the submontane belt (400-800 m) grading into spodo-dystric cambisols and ferro-humic podsols in the mountain and supramountain belt (800-1200 m). There are alpine soils (acidic ranker, lithosol) on flat summit plateau and extensive peat bogs, which have developed since the onset of postglacial Climatic Optimum to the Recent. At present, the whole range is dominated by Norway spruce that is native to the supramountain belt and to mountain beech-spruce forests of the mountain belt. The submountain belt was formerly characterised by mixed woodland with a high proportion of deciduous trees, which have been, however, replaced by spruce plantations since the 18 th century. In the eastern part of Krkonoše primeval forests have been already largely devastated by intensive exploitation during the14 th and 15 th centuries.
In a view of the above mentioned circumstances, the present day Krkonoše Mts. includes only a low number of areas providing favourable conditions for the mollusc fauna. This is particularly true of forest habitats, to which the main body of snail species was formerly confined. For this reason, it is not surprising that extensive areas of this mountain range are inhabited only by a few ecologically tolerant species.

History of research
Though the Krkonoše Mts. are the most widely known mountains with the highest peak of the Czech Republic the intensity of malacological research was not proportional to their importance. The first records of snails from the area of the Krkonoše Mts. were published in the second half of the 19 th century (REINHARDT 1874, CYPERS 1885, MERKEL 1894, ULIČNÝ 1892-1895, THAMM 1887. These oldest data were resumed by KÖHLER (1908). Not until 50 years later BRABENEC started a systematic research of the mollusc fauna of the Krkonoše Mts. especially in their eastern part -Rýchory (1967a,b, 1970). The data from the Polish part of Krkonoše Mts. were summarised by WIKTOR & WIKTOR (1968) and WIKTOR (1985). The findings of the arcto-alpine species Vertigo arctica and Columella columella in Malá Sněžní jáma (MERKEL 1894, WIKTOR 1968) and the description of a new subspecies endemic in the Krkonoše Mts. Cochlodina dubiosa corcontica (BRABENEC 1967a,b)

Methods
The review of literature on the area and unpublished records were given. Forty-seven sites were studied in 2004 and 2005 to complete the representative network of sites (see below). Combined standard five litre samples of litter and topsoil were collected from some sites. The samples were dried, washed, and organic material was -after repeated drying -sorted into separate size categories. Slugs and dendrophilous species were collected by visual search because they did not occur in litter samples. Freshwater molluscs were collected by using a bowl-shaped sieve (mesh size 0.5 mm) from water vegetation or sediments. Molluscs from the samples were sorted and determined (in some species of the families Arionidae, Agriolimacidae, and the genus Aegopinella by dissection) under a binocular microscope. The species names follow JUŘIČKOVÁ et al. (2007).

Recently researched sites
In the locality list below the data are given in the following order: locality number, locality name, geographical co-ordinates, altitude, date of investigation, and characteristic of site. Fig 1 shows

Results
Altogether 90 mollusc species were found in the Krkonoše Mts.: 7 species of freshwater snails, 4 species of bivalves and 79 species of land snails and slugs. The number constitutes 37.5% of the Czech Republic mollusc fauna. The list of molluscs at recently recorded sites shows Table 1.

The list of molluscan species from the KRNAP (i.e. Krkonoše National Park)
The list includes all mollusc species (hints in the literature and recent researches). Some of the species that occur just abroad the area of the KRNAP as well as some of the problematic species (probably inaccurate determination) are presented in a separate list. Species are aligned systematically according to JUŘIČKOVÁ et al. Helicidae Arianta arbustorum -common species from lower parts to the subalpine zone -e.g. Kotelní Jáma (K, C, B, J). Helicigona lapicida -talus slopes, stony walls, rocks. Common near Vrchlabí, Černý Důl (K), on Jizera River between Jablonec and Rokytnice (C), estuary of Maxův Potok stream, Klínový Potok stream, Dolní Dvůr -near church (B), Špindlerův Mlýn (P), Rokytnice -the cave, Bílá Skála near Jizerka River (L,J), Peklo quarry NE from Lánov, the old quarry E from Lánov, the ruins of Nístějka and Horní Štěpanice castles, limestone quarry NW from Vrchlabí (J) Scattered in suitable habitats, pure populations. Pisidium nitidum -Labe River in Vrchlabí (Be). Possibly more sites in lower parts.

Molluscan assemblages
The most important habitats of the Krkonoše Mts. from the malacological point of view are Sudeten cirques and boulder screes (Fig. 3) and mountain forests. Unfortunately, malacocoenoses of these habitats are relatively poore. The most important arcto-alpine species Vertigo arctica and Columella columella occur only in the polish part of the Krkonoše Mts., moreover V. alpestris was not found recently (WIKTOR & WIKTOR 1968, WIKTOR 1985, WIKTOR & FLASAR 2005. In the Czech part of the Krkonoše Mts. no arcto-alpine species were found. Aegopinella pura, Columella edentula, Vitrea subrimata, Arianta arbustorum occur in cirques, Carychium tridentatum, Oxychilus depressus, Perpolita petronella, Acanthinula aculeata, Causa holosericea in boulder screes with common eurytopic species Euconulus fulvus, Punctum pygmaeum, Vitrina pellucida, and Perpolita hammonis. In the Krkonoše Mts., the majority of area was covered by cultural spruce forest characterised by low number of acidotolerant species, especially in mushrooms. Typical species of this habitat type are Limax cinereoniger, Malacolomax tenellus, Lehmannia marginata, Arion fuscus (Figs 4 and 5), Perpolita hammonis, and Euconulus fulvus, which occur in similar habitats anywhere in the Czech Republic. In addition to it, mountain acidotolerant species Discus ruderatus (Fig. 6), Semilimax kotulae, and Lehmannia macroflagellata occur under the bark of spruce trees or stumps in the Krkonoše Mts. Richer forest malacocoenoses are confined to scattered fragments of natural mountain forests with beech and sycamore maple. Typical species of this habitat are an endemic subspecies of the Krkonoše Mts. Cochlodina dubiosa corcontica (Fig. 7) and other dendrophilous species -Clausilia cruciata (Fig.  8     substriata, V. pusilla, Clausilia pumila, Macrogastra ventricosa, Cochlodina laminata, Alinda biplicata). The richest malacocoenoses occur in scattered limestone parts of the Krkonoše Mts. In addition to the above, this area is inhabited by some sensitive forest species e.g. Platyla polita, Vitrea diaphana, Sphyradium doliolum, Ruthenica filograna. Characteristic landscape elements of this range are cliffs and talus slopes inhabited by Clausila parvula, Laciniaria plicata, Vertigo alpestris, Helicigona lapicida, Isognomostoma isognomostomos. The calcium rich habitats of castle ruins also inhabit rich malacocoenoses. (Fig. 9). Some synanthropic (Arion distinctus, A. fasciatus, Deroceras reticulatum), catholic (Trochulus hispidus, T. sericeus, Cepaea hortensis), and thermophilous (Vitrea contracta, Helix pomatia) species are characteristic for human impact habitats in the Krkonoše Mts. foothills or river valleys. At present, the invasive species Arion lusitanicus was found at two sites, although spreading of this species is probable in lower altitudes. Only fragments of open habitat assemblages (Vallonia pulchella, V. costata, Cochlocopa lubri-cella, Vertigo pygmaea, Xerolenta obvia) occur in lower parts of the Krkonoše Mts. The aquatic species Radix peregra, Galba truncatula, Ancylus fluviatilis, and Pisidium casertanum often inhabit streams and upper parts of rivers. Molluscs of ponds and other water bodies are rare in the whole area.

Discussion
In comparison to the part of the Krkonoše Mts. in Poland, the Czech part is richer in a number of species (68 species in Poland / 90 species in the Czech Republic) (WIKTOR & WIKTOR 1968). It is important to note that the list of species compared by Flasar from the literature (WIKTOR & FLASAR 2005) was not criticaly revised. He mentioned some species, which occur abroad the KRNAP or some problematic species (see above). In comparison to snail communities from comparable mountain ranges of the Bohemian Upland, the mollusc fauna of Krkonoše is rather poor both in species and in a number of fully developed woodland assemblages. Recent evidence reveals that this poverty is due to following principal reasons: The mutual interaction of severe climate, acidic rock and soil material has negatively influenced life conditions of the mollusc fauna since the beginning of Holocene warming. A number of Postglacial thermophilous immigrants expanding from their refugia in the Alpine (Aegopis verticillus, Cochlodina commutata, Itala ornata, Macrogastra badia as well as Petasina unidentata or Aegopinella nitens) or Carpathian regions (Faustina faustina, Monachoides vicinus, Macrogastra tumida, Vitrea transsylvanica) invaded the southern Sudetian foothills, but did not enter upper Sudetes. Only Cochlodina dubiosa corcontica and Eucobresia nivalis also colonised the central part of the Krkonoše Mts. In this context, it is worth mentioning that even the well preserved large beech forests in the adjacent Jizerské Hory Mts. are also poor in molluscs, which confirms the natural character of the malacofaunal poverty of the whole Krkonoše-Jizerské hory area. However, there are also long-term human activities that have disturbed the natural habitats since the Medieval Ages. Dense primeval forests have been exploited, cleaned and disturbed by grazing since the 14 th century so  that at the beginning of the 17 th century they were largely devastated. Large valleys were continuously settled, and dispersed cottages were built on the valley sides and on the summit plateaus. Later, a former mixed forest was replaced by spruce plantation that dominated the range up to present. They were heavily damaged by industrial air pollution during the second half of the 20 th century, which is also responsible for overall soil acidification. Due above-mentioned reasons, there can be no doubt that in contrast to natural state the present day mollusc communities are markedly impoverished. This is particularly true of the mountain forests whose original snail communities might resemble those of the Hrubý Jeseník Mts. where Alpine and Carpathian elements are also nearly missing, although they live in the adjacent foothills. The subalpine and particularly alpine belts have been permanently very poor in molluscs due to highly acidic soils and bedrock, which corresponds to similar observations on analogous ecosystems in other mid-European ranges.