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

Rare plant walk - 12

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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Road effects

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 for a second 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.

Roadsides host more plant species than the natural vegetation. That is the conclusion I drew in my previous post. While this difference is clear on low elevations, it vanishes as we get higher in the mountains, ending in similar species richness in the alpine zone above the tree line. Surprisingly, as can be seen on the graph, this pattern is the result of a higher diversity of alpine species (dashed grey line, white dots, versus the black line and dots representing the roadside) in the natural vegetation.

Graph native species richness

The alpine zone is a rocky, barren place without trees. That sounds as a bad thing for plants, but it also results in a higher availability of open places. The dominance of mosses and dwarf shrubs (like the crowberries mentioned in the previous post), is less intense here. More open spots, less competition, more diverse habitats, all kinds of factors that could explain the higher plant diversity as revealed by the graph. All of this explains the higher species richness on high elevations. But why don’t we have the additional higher species richness in roadsides here as well, as we saw in the lowland roadsides?

Alpine vegetation

Autumn in the Arctic mountains, the setting for our research. All pictures from the previous campaign in 2012.

Here is why: the higher amount of species in lowland roadsides comes from a bunch of typical roadside species, mostly highly competitive weeds (e.g. willowweed, Epilobium angustifolium, see picture). They do not belong in such numbers in the ‘traditional’ undisturbed subarctic mountain vegetation, but typically follow humans, agriculture and the availability of rich soils and mild conditions. Such culture followers form an important part of the lowland roadside vegetation. These species are added on top of the baseline species richness of typical subarctic mountain vegetation. Therefore: higher roadside diversity.

Hairy willowweed, a typical competitive weed

Epilobium angustifolium


These competitive weeds are rare in the roadsides on high elevations, where conditions are a lot harsher. The roadsides there serve more as a refuge for stress-tolerant alpine species, because the difference in environmental conditions with the surrounding undisturbed areas is much smaller: both contain open, low vegetation, with a lot of bare rock, exposed to the harsh climate. Ideal circumstances for stress-tolerant plants (like Saxifraga stellaris, see picture), yet a disaster for the competitive kind.

Saxifraga, a typical stress-tolerant alpine species

Saxifraga stellaris

Conclusion: the subarctic mountain road has a much smaller effect on native plants than its lowland counterpart. Lowland roadsides suffer from the invading pressure of competitive weeds, while they serve on high elevations more as a refuge for a wide diversity of alpine species.

Roadside vegetation

You want to know the exact scientific story? Here it is!


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Fallopia - 1

Fallopia japonica, or Japanese knotweed, a common non-native plant species in Belgium.

I have been hoping to expand my research area to my homeland for a while now. Working ‘On Top of the World’ never ceases to amaze, yet closer to home tons of intriguing questions arise all the time.

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Why is a non-native species – Fallopia japonica in this example – growing where it is growing? Why do we find the plant in so many spots, yet not others? What is the common denominator in all of these places, what is different?

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We are getting closer to that question, neatly disentangling all factors that possibly play a role. We have some great data to work with, and more great experiments in the pipeline.

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Hoping to write some more about this soon again.

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Summer - 2

Vicia cracca

Summer is upon us! Heaven for a botanist like me, with all shades of green and sparks of color popping up wherever you look.

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Rosa canina

Two consecutive winters of stubborn species studying is now again put to the test, and the results are promising: I think I have never recognised more plant species than now.

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Rhododendron ponticum

Yet the real test is still a few weeks away, when the snows finally melt above the polar circle in Scandinavia. Then I have to know them all, to resurvey the plots we put out there 5 years ago.

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Den nya Floran!

My new books arrived! Brand new version of ‘Den nya nordiska Floran’, the book that provides the foundation for all my research.img_20170519_103637_34650425311_o

Perfectly clear (and totally stunning) drawings and good distribution maps of all plant species in Scandinavia, the crucial attire for a botanist-ecologist investigating species distributions in the subarctic.

With this new set in my possession, enough to equip the team, I am feeling totally ready for the upcoming field season!


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