Trained as a botanist and phylogenetic systematist, since a decade I focus on biodiversity in urban areas. My main interest is in spontaneous plant growth and in soil/vegetation succession as a way towards nature inclusive cities. Most interesting is start from an ecological matrix in which architectural design and urban landscape development can be integrated in the total ecology of cities and their surroundings. A substantial part of my time I am teaching these topics to students from Leiden university and other academic institutions, including the supervision of BSc- and MSc-internships. I have several projects running in Amsterdam, Leiden, The Hague, and other areas in the west of the Netherlands. I especially pay attention to what can be called hidden biodiversity, small faunistic and floristic organisms, which play an important role in the urban ecology, but which are mostly neglected or even disliked. A recent focus is on soil biodiversity as the intricate soil biome is carrier of the above ground biodiversity. This has a.o. resulted in https://www.nai010.com/nl/publicaties/biodivercity-a-matter-of-vital-soil/245962.