Hi citizen! We have to thank you. Really, we are eternally grateful for what you do!

Let me explain: we have this interesting scientific question about non-native plant species in cities. We know they are there – tons of them, yet we want to study some patterns in their distribution and performance, among others related to the notorious Urban Heat Island effect.

The non-native Butterfly bush (Buddleja davidii) growing on a city wall in Mechelen

So we head out into the urban marvels of Flanders, ready to hunt down invasive plant species and measure their traits. Yet how to find them? We could not just randomly criss-cross through the country, looking at each leave we passed? That would be crazy – and way beyond what I would ask from a PhD-student.

It is there that you, the citizens, come in: there is tons of you out there, already finding all these species, and uploading your observations to fantastic citizen science platforms like iNaturalist and the Flemish Waarnemingen.be. Highly accurate coordinates, often illustrated with pictures of the plants.

Ailanthus altissima, the Tree of Heaven, growing happily on the side of a hot bridge over the ring around Antwerp. 

We just have to download those observations there, plug in the coordinates in our GPS, and navigate to the spot. 3 out of 4 times, we end up lucky, finding what looks like a needle in a haystack: our study species. Then we can measure where they are and how they are doing there, which promises to tell us a lot about the hows and whys of non-native species in the cities.

Pauwlonia tomentosa seedlings spreading on a parking lot of a train station. A location we would have never found without the help of the army of citizen scientists.

Stay tuned for these results, they are on the way! For now, just take the ‘thank you’, and please, please, keep recording all those observations, they are of such high value to so many ecologists out there. If you want to help us specifically – and you are in Western Europe – you can do so by recording any observation of our 8 woody city invaders via iNaturalist. Check out the project here, and go out to find them!

Abandoned building sites, hotspots for non-native species in the cities.

We are recording observations of 8 common non-native woody plant species in Western European cities, to study their distribution across the urban-rural gradient. You can help by uploading your obervations of those species to iNaturalist here! Focussing on Paulownia tomentosa, Ailanthus altissima, Buddleja davidii, Senecio inaequidens, Berberis aquifolium, Cornus sericea, Prunus laurocerasus and Symphoricarpos albus.