The Eurasian steppe belt: Status quo, origin and evolutionary history
We present a comprehensive review of the characteristics and structure of the Eurasian steppe and of its evolutionary history in space and time. During the last decades, tremendous advances in research methods in earth and palaeontological sciences have greatly increased knowledge on palaeoclimates and palaeoenvironments of the Cenozoic era. We discuss well-known facts against the background of the recent progress made in these fields and others related to our topics, and address open questions. In Part I (Status quo), we deal with steppe classification systems, human impact and present state of the Eurasian steppe. Here, we concentrate on prehistoric times when the first human cultures emerged, and on the last 100 to 200 years when drastic changes occurred and in many regions steppe nearly completely disappeared. In Part II (Origin and evolutionary history of the Eurasian steppe) we attend to the origin and evolution of grasses and grassland in general, and to the evolution and climate/landscape history of the Eurasian steppe belt in particular. Uplift of the Himalayan-Tibet Plateau, changes in land-sea distribution and global climate trends have been invoked as driving forces behind Cenozoic paleoclimate changes, but there is little consensus which one is the most important driver. We finally identify gaps/challenges in our knowledge about the evolutionary history of the Eurasian steppe and discuss research directions, which might help to unravel the florogenetic and steppe habitat dynamics from the beginning of steppe formation to the present time.