This is a guest post by Charly Geron, PhD-student at Gembloux Agro-Bio Tech and in our Virtual Lab.
One month ago, I was left with mixed feelings about finishing up my second field season, and acquiring massive amount of data on a part of my PhD. It was so nice to actually have finished everything on time in the field, but also a bit sad to not going back to the places I visited 2 years in a row!
But please, let me recap what happened since april 2018!
At that time, with my supervisors, we decided to study how urban environments are impacting alien plant development. We then focused on studying the development of the most widespread alien Asteraceae species along Belgian urban-rural gradients. Indeed, this is one the plant family with an impressive high number of aggressive invasive species.
It was with great excitement, that I dived in the practical organization and looked for ways to select and find plants in areas of interests. In fact, for the success of my experiment, I needed plants in every possible anthropogenic habitat in my study zone, an area as big as half of Belgium. No need to say that I was a tiny bit anxious to drive around thousands of kilometers looking for my plants with no clue of where they could be.
That’s when we had the idea (not knowing if it would work) to use the data of a naturalist citizen science platform named waarnemingen.be or observations.be (depending if you prefer the Flemish or Wallonian version) as a source of observations. Now owning thousands of records (GPS points that can be as precise as a few meters) of my chosen species, I selected focal areas to look for my plants.
Map of the selected areas to look for my plants in Belgium. Each red dot corresponds to an area where the alien plant species had to be spotted. Just to give you an idea, more than 250 plant individuals were studied during each of the 2018 and 2019 field seasons.
The first field days began in July 2018 under a scorching sun, excited to find out if the plan could be successful (luckily, I got help of so many kind people during these long field days in urban labyrinths). And so it seemed: the method was great. I often found the plant exactly at the coordinates uploaded by kind strangers to the internet some time ago. Indeed, happily enough, from times to times, I was discovering tiny, almost undetectable plants in an urban jungle.
Found it! This tiny Solidago gigantea was found back at the exact spot where a kind stranger did register it some time ago. Amazing!
We had glorious surprises (for my experiment, less so for local biodiversity) such as finding huge colonies of flowering non-native species glistening in nice understory vegetation.
Telekia speciosa in full bloom spreading around in a forested park close to Bruges, picture courtesy of Jonas Lembrechts.
After only 11 field days, recording stress levels of the plants (leaves’ pigments, development variables, etc.), the 2018 field season of this part of my PhD was already finished! Hooray! Even better for me, the weather was nice enough to offer record breaking bright and warm days, perfect to study the impact of urban environments under global warming!
Measuring leaves’ pigments such as chlorophyll to detect whether or not this Artemisia verlotiorum is feeling good.
This summer, more precisely in late June, I did re-survey the locations of my 2018 field season. Indeed, to better understand the conditions experienced by alien plants in urban environments, it is nicer to include inter-annual variation. I got lucky enough to get two contrasting weather periods between summer 2018 and summer 2019.
Almost 39°C in the full sun back in July 2019 in Brussels. Summer 2019 was less warm, but more variable, with intense heatwaves. I’m sure you experienced the uncomfortable heat escaping from urban structures such as pavements in hot days.
I was happily surprised to be reunited with most of my plants from last year. Of course, some places changed drastically. That’s when I really understood how fast anthropogenic environments are evolving! Urban brownfields where I could see thousands of my ruderal alien plants last year now turned in to fancy brand new housing. Despite some bad luck spots, I was also able to wrap up my second field season, studying about 270 plants and this time in only 7 days!
A rather strange place to keep your stroller, but a perfect place to spot ruderal alien plant species.
Following a recent blogpost here, I am so grateful to all the people that are doing citizen science initiatives! They are helping science more than they expect! They saved me so many working days, especially the difficult but exciting task of finding species where they develop.
More will follow later about the findings following these two years of data acquiring. So please stay tuned to learn how urban versus rural environments are limiting or helping alien plant species. For now, off to work to incorporate the data acquired this year to my expanding data sheets.