Substrate associated biogeographical patterns in the north-western Pannonian forest-steppe

Abstract

The north-western part of the Carpathian Basin is an important biogeographical crossroad. This transitional area between the forest-steppe biome of the Pannonian biogeographical region and the temperate forest biome hosts scattered patches of natural steppe embedded in forests, especially in rugged landscapes. The unique geographical position is reflected in the plant assemblages, which are composed of species of different origins, mainly central-European, continental, Mediterranean and sub-Mediterranean. We sampled sites with well-preserved forest-steppe vegetation on different substrates across this region. At each site, we sampled the vegetation in three habitats: steppe, forest and ecotone. We then attempted to disentangle the influence of geographical location, climate and substrate on the species composition of forest-steppe landscapes and the percentage of the species with a particular type of distribution. We found that substrate is the main factor determining species sorting. Substrate is also largely responsible for the percentage of species with particular types of distribution. While continental species are most frequent on loess, Mediterranean species are mainly found on andesite. Sub-Mediterranean species are most frequent on dolomite and rare on loess. The distributions of these species can be explained by the environmental conditions in the core of their native ranges. The complexity of the distribution patterns of species in the north-western Pannonian forest-steppe shown in this study should be considered in the discussion of the environmental history of the region and conservation planning.