Live from the field

We are currently on a ten day fieldtrip to the beautiful Lapland, where we are monitoring the movement of plants along mountain roads.


A job with a view, plenty of beautiful alpine and arctic plants, and a ton of great and interesting data coming in. More pictures and stories will follow, but now the field calls!

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Impatiens - 2

Time for a plant portrait of one of my favourite Belgian study species: Impatiens glandulifera, a tall herb with its origin on Himalayan mountain slopes, yet introduced all over the world by humans who fell in love with it.

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And what’s not to love about the Himalayan balsam? The flowers are beautifully original and shaped like a weird pink hat, earning the plant its common English names ‘Policeman’s Helmet’, ‘Bobby Tops’ and even ‘Gnome’s Hatstand’. 

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Yet when the delicate pink flowers disappear, the fun is all but over: the genus name Impatiens refers to the plant’s method of seed dispersal. When you touch the ripe seed pots, they ‘impatiently’ explode, scattering the seeds in all directions. I bet you this provided hours of fun as a child in my parent’s garden!

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Yet it is exactly this attractive but aggressive method of seed dispersal, coupled with a high nectar production that attracts countless pollinators, that makes the plant so successful. In many regions in Europe and North America, the plant easily outcompetes the native vegetation, especially along rivers.

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It is in that last environment that it provides the most trouble as well. Similar to that other invader, Japanese knotweed (Fallopia japonica), the Himalayan balsam dies off in winter dies off in winter, leaving the river banks bare and unprotected. Such an environment is much less protected against erosion by winter floods than a river bank covered with native reed (Phragmites australis) for example.

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Science with doormats


No, I am not investing in a soccer field, nor am I building an indoor garden for my cat (although the latter loves the idea).


No, we are planning to dive deep into the study of the movement of plant species along mountain roads. Do I need a bunch of weird-looking doormats for that? Yes, as it is the ideal material to trap seeds falling on them.


We will install these mats on strategic spots in in the landscape and then just wait. After the growing season, the mats will be taken to the lab and all seeds trapped in the hairs will be carefully collected and identified.


Even more than just looking where the plants currently are, it will reveal their potential spread in the future. Hopefully more on that later.

And, oh yeah, do not laugh with my mats, they are a proven, published and peer-reviewed tool!


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Aliens and their way to the top

5 years later, we are getting ready for a re-survey of our longterm observational plots along the roads in the Norwegian mountains. The perfect moment to summarize what we learned from our first trip. This post was published first in a series on this summer’s field trip on the INTERACT blog.

Remember my story about how lowland roadsides are flooded with species that do not  belong in the natural system? Remember how these new species could profit from the lower competition when the natural vegetation got destroyed by the process of road building? A lot of these species are well known to Northern Scandinavia, but some of them are not. And this last group deserves our special attention.

A group of true culture-followers. The real roadside species. The ultimate weeds. They followed human development up to the north at one point in time, some decennia or centuries ago. We call them aliens: visitors (and sometimes invaders) from another ‘world’. (But do not let them fool you, because they are just species like our regular white clover!)

Trifolium repens

What is really curious is how almost all these aliens share the same story. Their invasion always starts in the lowlands, where they got introduced, after which they closely follow roads and human structures up into the mountains. Not too many of them really reach the top, however. We see a progressive drop-out of species on the way, victims to the cold alpine climate (but keep in mind this is a dynamic process, they could still be on their way!). This progressive loss of alien species with elevation got the fancy term ‘directional ecological filtering’ and it also seems to be happening in our subarctic ecosystem. The mountain acts as a filter, only allowing a select group of aliens to the highest elevations, while the weaker ones are filtered out (check the clear decrease in roadside alien richness with elevation as visualized by the black line on the graph).

Alien species richness with increasing elevation in the roadsides (black) and the natural vegetation (grey).


The question is which skills are needed to sneak through this filter to reach the highest elevations in the mountains. It turns out that all winners of the race to the top follow a similar strategy: they are all generalists, which means they can thrive in a wide range of environments. That makes them different from the vast majority of plants that got adapted for one particular situation. It also makes them incredibly suited for mountain invasion. Mountain invaders have to overcome both lowland and alpine conditions. Strong competitors loom in the lowlands, where conditions are good and fast and efficient growing are the keys. In the highlands, the harsh climate demands stress-tolerant traits to survive the cold: growing slow, staying close to the ground and using resources to fight the harsh conditions.

Summer snow

That is the reason why pure competitive alien species are stuck in the lowlands, while the generalists can follow the road all the way up to the alpine zone. While both know how to handle the intense competition in the lowlands, only the generalists can change their strategy to deal with the totally different alpine conditions from the highlands. And as soon as these generalists reach the top, they might become problematic and start escaping the roadsides, yet that’s a story for another post to tell.

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So dry


It is dry in Western Europe. Extremely dry. Dry enough for me to to write a blogpost about it for, our local popular science journal. They asked me if the current drought could serve as proof that the climate warming.


Unfortunately, the blog is in Dutch, yet I’ll hint the answer for you: it’s not. We should always be wary about the difference between one weather event – no matter how extreme – and the global climate.


Potato flowering in a hot evening sun. Especially agriculture is suffering from the drought.

Yet the drought does fit in neatly in the observed ànd predicted increase in extreme weather events that come with climate change: more droughts, more heat waves, more and heavier storms… We are up for some years in which one weather record after the other will be broken, as climate gets more and more unpredictable.

And I think it is crucial that we are all aware of that fact.

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Hidden treasures on the campus

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The common spotted orchid (Dactylorhiza fuchsii) 

When you think about a quest for rare plant species, you might imagine high-spirited adventurers travelling to the ends of the earths on a hunt for tropical flowers hidden in the depths of the jungle. Who might have imagined that rare plants are often hiding right underneath your nose, waiting to be discovered?

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A spotted longhorn (Rutpela maculata) on common spotted orchid

Last week, the Global Change Ecology center from the University of Antwerp organised an excursion for such easily overlooked botanical treasures. Destination of the expedition as down-to-earth as can be: the university campus itself.

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Discovering the orchid meadow at the campus

Guided by a fascinatingly well-informed local botanist, we took off on a lunch walk towards the hidden botanical hotspots on our campus. And these hotspots were all more unexpected than the others: an overgrown pond, a forgotten corner next to a building, or even right in the middle of the parking lot.

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Discovering botanical treasures in the middle of the parking lot

Yet these extraordinary ordinary destinations made the harvest of this short scientific mission even more impressive: beautiful orchids, rare ferns and horsetails, and even an obscure tiny patch between two stones that listened to the name ‘hairy rupturewort’.  For several of these species, only a few populations can be found throughout Flanders.

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Hairy rupturewort (Herniaria hirsuta), easily overlooked, yet one of the botanical stars of the university campus

This surprising lunchtime walk serves as an example that even a green patch this close to home can host significant natural value. Just a few steps out of the office, and a whole botanical paradise enfolds. Yet at the same time it should be a reminder that we should not give up on this local nature too easily, no matter how disturbed and disrupted it might look. An ecologically inspired management plan for the green areas on the campus – or anywhere in the city for that matter – can play a crucial role here.

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Black spleenwort (Asplenium adiantum-nigrum) in an ignored ditch on the parking lot.

So please, do not just think of your local patches of nature as economical opportunities, and give them the ecological care they deserve. Our botanical treasures thank you.

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Rough horsetail (Equisetum hyemale) sprouting in a concrete trail

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A skipper and a damslefly interacting on a knapweed flower

Ecology is all about interacting. Interactions with the environment, interactions with the organisms living in this environment. A unimaginable multi-dimensional hyperspace-like spiderweb of interactions. A life-long source of scientific amazement. I love it.

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