Central European forest–steppe: An ecosystem shaped by climate, topography and disturbances.

The occurrence and origin of dry grasslands and their rich biota in the moderately humid Central‐European climate have fascinated scientists for over a century. Modern palaeoecological and phylogeographical data support earlier hypotheses that these grasslands are late Pleistocene relicts and can therefore be considered part of the Eurasian forest–steppe biome. However, it is still unclear which factors fostered the maintenance of steppe patches in Central Europe throughout the Holocene. Here, we provide an overview of the main hypotheses, which stress, respectively, the effects of climate, edaphic conditions and disturbances. We then develop a general conceptual framework on how these three factors interact to form forest–steppe mosaics. We thereby emphasize the role of topography as a crucial control on forest–steppe patterns at the landscape scale. Topography is related to several mechanistic drivers that influence vegetation processes, such as near‐surface microclimate and soil formation. Consequently, topographic variation allows both forest and steppe patches to occur beyond their macroclimatic niche, favouring the development of forest–steppe mosaics. To illustrate our framework, we demonstrate the interactive effect of macroclimate and topography on the occurrence of steppe patches at 108 selected Central European forest–steppe sites. Although we developed our framework focusing on the current distribution of Central European forest–steppe, we suggest that it contributes to the understanding of similar transitions between temperate forest and steppe biomes in the past as well as elsewhere in the world. [ABSTRACT FROM AUTHOR]