All over the globe, the urbanisation of landscapes is increasing. 60% of the land surface which is expected to be urban by 2030 is currently not built on at all. How this will impact on biological diversity will only be apparent in retrospect. However, for most cities there have been systematic surveys of biological diversity, although only since the second half of the 20th century. Researchers at the Helmholtz Centre for Environmental Research (UFZ) and the German Centre for Integrative Biodiversity Research (iDiv) have now revealed, on the basis of historical data, how plant diversity in the region of Halle an der Saale has changed in over 300 years of urbanisation, and have also made predictions about the future.