Phytogeography of the sandstone areas in the Bohemian Cretaceous Basin (Czech Republic/Germany/Poland)

Abstract

Most sandstone regions in the Bohemian Cretaceous Basin have a landscape structure with core zones formed by an acidic pseudokarst (covering tens of square kilometres and a high percentage of the total area of the particular sandstone region), surrounded by forests, plateaus and locally occurring wetlands and calcareous sandstone outcrops. Other ecosystems (e.g., settlements, fields, alluvia, volcanic hills) are present mostly as patches or linear corridors. In contrast to most cultural landscapes, the species and community diversity in sandstone regions is significantly lower in the prevailing ecosystem types (on pseudokarst) than in locally occurring habitats. Therefore, a higher biodiversity in sandstone regions (formed of prevailing quartzose sandstones) is not related to landscape matrix but to patches (calcareous sandstones, volcanic hills, wetlands, etc.) and corridors (water streams). This is primarily due to the nutrient-poor substratum of quartzose sandstones. For this reason, the vegetation of sandstone regions, formed mainly by quartzose sandstones (e.g., Elbe Sandstones), varies significantly from regions with a higher proportion of other substrata (e.g., Polomene hory Hills) or those with large areas of open cultural landscape (e.g., Bohemian Paradise). Despite sharing many similar features of flora and vegetation, the biodiversity of a particular sandstone region, in the Bohemian Cretaceous Basin, varies significantly due to different combinations of basic factors. The substratum (quartzose/calcareous sandstones), relief, altitude, microclimate and oceanity/continentality seem to be crucial elements that determine the final features of the natural vegetation in a particular sandstone landscape (Sadlo, Hartel and Markova, this volume). However, in cultural parts of these landscapes the importance of these primary factors can be substantially overlaid by human influence. Floristic differences among sandstone regions, based on different representations of phytogeographic species groups, are presented in Table 1. In the following overview, the natural conditions of the individual sandstone regions of the Bohemian Cretaceous Basin are characterized with a particular focus on the flora and vegetation. For this survey, regions are geographically defined using the phytogeographic division of the Czech Republic (Skalický 1988). Where the sandstone regions extend into Poland and Germany these areas have also been included. The location of these sandstone regions can be seen in Figure 1. In the description of flora and vegetation, the volcanic patches were intentionally omitted because they are an independent source of biodiversity that barely interacts with the surrounding landscape. The phytogeographic characteristics used (sub-oceanic, sub-montane species, etc.) should be understood in the Central European context, rather than absolutely. Plant communities are summarized in the appendix. Phytogeography of the sandstone areas in the Bohemian Cretaceous Basin (Czech Republic/Germany/Poland)