Phytogeography of the sandstone areas in the Bohemian Cretaceous Basin (Czech Republic/Germany/Poland) Handrij Härtel1,3, Jiří Sádlo1, Krzysztof Świerkosz2 and Ivana Marková3 Keywords: Bohemian Cretaceous Basin, phytogeography, Despite sharing many similar features of flora and ve- vegetation getation, the biodiversity of a particular sandstone region, Species nomenclature: vascular plants: Kubát et al. (eds.) in the Bohemian Cretaceous Basin, varies significantly due (2002), bryophytes: Kučera and Váňa (2003) to different combinations of basic factors. The substratum (quartzose/calcareous sandstones), relief, altitude, microclimate and oceanity/continentality seem to be crucial elements Introduction that determine the final features of the natural vegetation in Most sandstone regions in the Bohemian Cretaceous Basin a particular sandstone landscape (Sádlo, Härtel and Marková, have a landscape structure with core zones formed by an this volume). However, in cultural parts of these landscapes acidic pseudokarst (covering tens of square kilometres the importance of these primary factors can be substantially and a high percentage of the total area of the particular overlaid by human influence. Floristic differences among sandstone region), surrounded by forests, plateaus and sandstone regions, based on different representations of locally occurring wetlands and calcareous sandstone phytogeographic species groups, are presented in Table 1. outcrops. Other ecosystems (e.g., settlements, fields, alluvia, In the following overview, the natural conditions of the volcanic hills) are present mostly as patches or linear individual sandstone regions of the Bohemian Cretaceous corridors. In contrast to most cultural landscapes, the Basin are characterized with a particular focus on the species and community diversity in sandstone regions is flora and vegetation. For this survey, regions are significantly lower in the prevailing ecosystem types (on geographically defined using the phytogeographic division pseudokarst) than in locally occurring habitats. Therefore, of the Czech Republic (Skalický 1988). Where the sandstone a higher biodiversity in sandstone regions (formed of regions extend into Poland and Germany these areas have prevailing quartzose sandstones) is not related to landscape also been included. The location of these sandstone regions matrix but to patches (calcareous sandstones, volcanic can be seen in Figure 1. hills, wetlands, etc.) and corridors (water streams). This In the description of flora and vegetation, the volcanic is primarily due to the nutrient-poor substratum of quartzose patches were intentionally omitted because they are an sandstones. For this reason, the vegetation of sandstone independent source of biodiversity that barely interacts regions, formed mainly by quartzose sandstones (e.g., Elbe with the surrounding landscape. The phytogeographic Sandstones), varies significantly from regions with a higher characteristics used (sub-oceanic, sub-montane species, proportion of other substrata (e.g., Polomené hory Hills) etc.) should be understood in the Central European context, or those with large areas of open cultural landscape (e.g., rather than absolutely. Plant communities are summarized Bohemian Paradise). in the appendix. 1 Institute of Botany, Academy of Sciences of the Czech Republic, CZ-25243 Průhonice, Czech Republic, e-mail: [email protected]; [email protected] 2 Museum of Natural History, Wrocław University, ul. Sienkiewicza 21, PL-50-335 Wrocław, Poland, e-mail: [email protected] 3 Bohemian Switzerland National Park Administration, Pražská 52, CZ-40746 Krásná Lípa, Czech Republic, e-mail: [email protected] 177 SANDSTONE LANDSCAPES Figure 1. Main sandstone regions of the Bohemian Cretaceous Basin following the phytogeographical divisons of the Czech Republic (following Skalický 1988, modified) As in the previous paper (Sádlo, Härtel and Marková, this locally along the Elbe River. The core part of Elbe Sandstones, volume), it has not been possible to include definitive formed by pseudokarst and covering approximately one- localities, collectors and literature citations. Nor has it third of the region, is a forested and almost completely been possible to distinguish between historic and recent uninhabited sandstone landscape, protected as the Saxon records. More information about flora and phytogeography and Bohemian Switzerland National Parks (Figure 2). In of sandstone areas in the Bohemian Cretaceous Basin can addition to the rock cities, another unique component of be found, e.g. in Förster (1968), Härtel (2005), Härtel and the landscape is the massive Elbe River canyon with its Marková (2005), Kubát et al. (eds.) (1999), Kučera and high rock walls. In the past, acidophilous beech forests Špryňar (1996), Militzer (1960), Müller (2003), Petříček (Luzulo-Fagetum) were dominant in the Elbe Sandstones. (1987), Riebe et al. (1999), Slavík (1977), Sýkora (1975), Today, these forests have been largely replaced by planted Sýkora and Hadač (1984), Świerkosz (this volume), Vogel Norway spruce forests. Acidophilous pine forests (Dicrano- et al. (1993), Zittová-Kurková (1984). Pinetum) are abundant on cliff edges. Pine-oak forests (Vaccinio vitis-idaeae-Quercetum) occur fragmentarily on plateaus and waterlogged spruce forests (Mastigobryo- Elbe Sandstones Piceetum) in deep and narrow gorges. When compared with This region is defined by one main continuous sandstone other sandstone areas, this region is characterized by cluster. Denuded pre-Cretaceous rock outcrops occur dominant quartzose sandstones and other sediments are 178 PHYTOGEOGRAPHY OF THE SANDSTONE AREAS Figure 2. The core of the Elbe Sandstones with large rocky and forest areas which is protected as the Saxon-Bohemian Switzerland National Park (Photo by Zdeněk Patzelt) rare. Among sandstone regions in the Bohemian Cretaceous brownianum, Hygrobiella laxifolia, and Anastrophyllum Basin, Elbe Sandstones have the widest altitudinal range michauxii (deep gorges in the pseudokarst) grow. The (110–726 m a.s.l.) (Table 2). The ecological effect of this three latter species are recently known only from Elbe large elevation difference is, however, modified by a strong Sandstones in the Czech Republic. The region’s climate, climatic inversion in the deep valleys and gorges where which for the Czech Republic is considerably oceanic, (sub)montane vascular plants such as Dentaria enneaphyllos, significantly influences the species composition. Examples Festuca altissima (Elbe River canyon), Viola biflora, Circaea of (sub)-Atlantic species are the ferns Trichomanes speciosum alpina, Streptopus amplexifolius, Lycopodium annotinum (gametophytes), Blechnum spicant, Hymenophyllum and bryophytes Dicranum majus, Geocalyx graveolens, tunbrigense (†), the angiosperms Galium saxatile, Juncus Lophozia grandiretis, Harpanthus scutatus, Tetrodontium acutiflorus, Hypericum humifusum, H. pulchrum (Figure 3), Luronium natans and Epilobium hypericifolium (†) and the bryophytes Fissidens rufulus and Plagiothecium undulatum. Boreal to boreo-continental elements can also be found, for instance Eriophorum vaginatum, Oxycoccus palustris, Ledum palustre and Empetrum nigrum, the occurrence of the latter two species is mainly on cliff edges above the gorges with climatic inversions and is characteristic for this region. The low species richness and the floristic uniformity of the large pseudokarst areas are striking. These can be attributed to the extent of the nutrient-poor quartzose sandstones and the effect of the Norway spruce plantations. The region’s diversity is increased in the areas adjacent to České středohoří Mountains, on volcanic hills and in the Elbe River canyon with its mesoclimatic effect, where the above-mentioned montane species combine with the Figure 3. Hypericum pulchrum is a species with a sub-Atlantic thermophilous species (Picris hieracioides, Trifolium distribution. Within the Bohemian Cretaceous Basin this species alpestre, Acer campestre, Stachys recta, Petrorhagia prolifera, occurs in the Elbe Sandstones only (Photo by Petr Bauer) Dactylis polygama, Thalictrum minus), often, however, 179 SANDSTONE LANDSCAPES limited to the pre-Cretaceous bedrock and/or the synanthropic Lonicera nigra, and Petasites albus occur in deep valleys biotopes. or at higher elevations on mainly volcanic hills. Small wetlands, peat bogs and heaths (Brazilka, Nolden- teich, Jedlovské rybníky Ponds) host Drosera rotundifolia, Lusatian/Zittau Mountains Pedicularis sylvatica, Oxycoccus palustris and the bryophytes and the Podještědí Region Sphagnum fallax, S. fimbriatum, S. palustre, Warnstorfia This area is relatively heterogeneous. The Lusatian/Zittau fluitans, W. exannulata, Caliergon cordifolium etc. The Mountains and the Podještědí Region share a landscape rare occurrence of Ledum palustre in this region is restricted with only sparse forms of the sandstone pseudokarst and to the peat bogs and is not found on the cliffs. In the vicinity have been incorporated into one region. It includes the of Chřibská, Carex davalliana, C. pulicaris, Epipactis territory at the margins of the Bohemian Cretaceous Basin palustris, Triglochin palustris, Dactylorhiza fuchsii, separating the Elbe Sandstones from the Ralsko-Bezděz Eriophorum latifolium etc. grow on marls. Plateau. Quartzose sandstones predominate in this region. The Českolipská kotlina Basin shares many species with However, the typical sandstone landscape is strongly the adjacent Ralsko-Bezděz Plateau. fragmented into minor