Forward into the past - flora falsification or post-glacial normalisation?

Prof Dr Maximilian Weigend (University of Bonn)

We have been observing changes in the vegetation in Europe for years - oak forests on dry sites on the Middle Rhine are dying off and developing into open landscapes, beech forests are collapsing and the species composition in the undergrowth of oak-hornbeam forests is shifting dramatically. At the same time, species from warmer climate zones - especially "neophytes" from horticultural cultivation - are increasingly spreading into the open landscape. These processes are also the result of changing climate parameters due to climate change - through changes in the amount and distribution of precipitation, average temperatures and temperature and precipitation extremes. This favours the increase in so-called "Mediterranean" and "laural" plants from the Mediterranean region, the Caucasus, the south-west of the USA or western China. These species groups, which also determined the vegetation in Central Europe before the ice ages (in the Pliocene and Miocene), are often better adapted to our current climate than "native" species. They are returning - after a long absence. We are therefore at the beginning of a fundamental large-scale reorganisation of biodiversity, which differs from numerous similar processes in recent geological history primarily in terms of its speed and the long-distance dispersal dramatically facilitated by humans. This has far-reaching consequences for ecosystems.

Photo: Fruiting "Chinese hemp palm"(Trachycarpus fortunei) in the Botanic Gardens of the University of Bobb. The hemp palm was widespread throughout Eurasia before the ice ages and survived only in East Asia and the Himalayas. It is beginning to re-establish itself in Europe, starting from gardens. M. Weigend