Data gathered by habitat mapping programs can make important contributions to biodiversity research. They provide insight into changes of the local flora since the 1980s—a period that is not well covered by other sources of information. A team from the Martin Luther University Halle-Wittenberg and the Hamburg Authorities for the Environment, Climate, Energy and Agriculture has now shown how research can benefit from this historic habitat mapping data using habitat maps of the city and federal state of Hamburg as an example. Their results, which have been published in Ecosphere, also show a clear decline of species-rich habitats due to urbanization over the last decades.