I just returned from a journey to the stunning neo-Renaissance castle of Průhonice, located just a short bus ride away from the almost as magical city of Prague. But what brought me to such a picturesque location? Well, let me tell you about the meeting we had with the ASICS network.

The castle of Průhonice and its surrounding botanical garden, home to the Institute of Botany of the Czech Academy of Sciences. A place full of ecological research of the highest level, and an inspiration to its visitors.

The ASICS network is an international group of scientists dedicated to studying the distribution of non-native species in cold environments. These environments include both high latitudes and mountains which, due to their remoteness, often escape our attention. But why is it so important to study non-native species in these extreme conditions?

Over plates of delicious strudel and other Czech delicacies, we delved into discussions about the progress we were making in understanding non-native species’ invasions in these cold environments. We saw stories of beetles on Crozet Island, of springtails on Marion Island, of non-native plants on Svalbard, each tale more exotic than the rest.

The castle not only hosted our meeting, it’s also the scientific home of our colleagues of the Department of Geoecology, better known as the developers of the TOMST TMS4 microclimate sensor. You won’t be surprised to hear I was delighted to visit them and talk microclimate!

While outside the castle walls, the Czech spring was getting into full spring, we discussed how non-native species were dealing with the extreme weather conditions in these environments. We summarized what we knew, and what we still don’t know.

All around us in the botanical garden, springflowers were emerging. With the sun an agreeable 17°C, it was high tide for botany! Here: Hepatica transsilvanica

Despite the challenges, the conclusions of the meeting were promising: we were gathering more data than ever before on the distribution, behavior, and limitations of these species. However, these cold environments remain full of black boxes, and there are still so many aspects that no scientist has ever looked at. For example, have you ever wondered about the invasion of invertebrates in mountains? Few have, so it seems, and the amount of data is worryingly low. We simply don’t know if there are any non-native invertebrates crawling uphill!

Comma butterfly enjoying the spring sun

The best part is that thanks to ASICS, we now have an ambitious, international, and highly diverse team of dedicated individuals joining forces to answer these questions. We are bringing datasets together, sharing expertise, setting up joint protocols on a global scale. Our hopes are that together, we will not only be able to answer more questions than alone, but that we can also bring the world’s attention to the urgent need for conservation of these remote locations.

Posted in Czech Republic, General | Tagged , , , , , , , , , | Leave a comment

Virtual SoilTemp symposium

I am very happy to invite you to a virtual SoilTemp symposium, on May 8th, 2023, from 15h-17h30 Brussels time.

At this symposium, we will:

– Introduce the status of the database on its way to publication
– Provide summary presentations of the ongoing global SoilTemp projects
– Showcase the new data submission format for a final round of data submission before database publication
– Have an open floor for 5-min presentations by the community on SoilTemp-related topics (submit your abstract via the form below).
– Answer questions on the use of the database and data submission

For those for whom the timing does not work, there will be an add-on session on Friday, May 12th, 2023, from 9h-10h30 Brussels time. Here, we will summarize the key messages with room for questions. 

Please, let me know your interest in this symposium through this form!

Please spread the word and invite your colleagues! This symposium is open to all and THE opportunity to get in touch with the network towards publication of the database itself. We will soon start one final push for data submissions towards that publication, which we plan to finish in autumn 2023 (so this will be the final chance for anyone to contribute data and get an invite to co-author our big database). More information on this will follow!  

Looking forward to seeing many of you at our symposium!

Picture by Stijn Van de Vondel
Posted in General | Tagged , , , , , | Leave a comment

The impact of the pines

Picture this: it’s the 20th century and people are planting pine trees all over Chile. Pines of the genus Pinus, that is, which is very different from the native Araucaria araucana (the monkey puzzle tree). The latter might very well be called the ‘Chilean pine’ by some, but lacked the versatility for those wanting efficient wood production and erosion protection. So: in come the Pinus-pines, to help the economy!

A line of lodgepole pines (Pinus contorta) planted above the treeline at the foot of the Lonquimay-volcano

These might have looked like good ideas – and perhaps still do too many – but now the tables have drastically turned: these pines have spread like wildfire and are causing havoc on the ecosystem. Indeed, those pine trees have the tricky habitat not to remain where they are, and especially in the native Chilean landscape of Araucaria forests and Patagonian steppe, pine trees come across very little resistance. As a result, the once so characteristic landscape is now a tangled mess of pine branches and trunks.

A dense stand of expanding lodgepole pines, with stems growing in all directions, creating an understory that is almost impossible to pass

But what’s happening beneath these dense canopies? How much are the microclimate and soil suffering from these stubborn pine trees? And, even more importantly, what is the impact of these changes on the native vegetation? In a recent study led by our Chilean partners from the University of Concepcíon, we set out to investigate this effect for invasions of lodgepole pine (Pinus contorta). We measured everything from temperature to soil pH to nutrient availability across a gradient of pine biomass, from scattered individuals to dense entanglements.

Pinus contorta biomass significantly correlates strongly with a wide range of environmental conditions: more pines result in buffered temperatures, loss of light, loss of Potassium, decreased pH and increased litter depth.

Our results – published in ‘Diversity – were alarming – the impact was as huge as we suspected based on visual assessment alone. The more pine trees, the worse it got. The local micro-environment was drastically altered, resulting in a loss of light and nutrients, decreased pH, and increased litter depth, amongst others. But our biggest worry? The native plant diversity was virtually wiped out in the most densely invaded plots.

Native plant species richness (top) and abundance (bottom) decreased significantly with increasing pine biomass, both in the Araucaria-forest (left) and on the Patagonian steppe (right).

Our study revealed that it is probably the interplay of all these environmental factors – all so dramatically changed from background conditions – that explains the progressive drop in native plant species in the understory. Indeed, few native species likely have the necessary flexibility to deal with changes in all these defining environmental characteristics at once. The mechanisms behind the loss of biodiversity of native species associated with plant invasion would thus not only depend on the competition exerted by P. contorta, but also on the modifications that this species exerts on the abiotic environment. Moreover, these microenvironmental changes can have significant effects on other functional groups (e.g., pollinators, decomposers) with important consequences for the whole trophic network of the invaded ecosystems.

Scattered pine trees in between a few old and persistent Araucaria trees

So, what’s the plan of action? Can we get rid of these pine trees, and if so, what happens to the microenvironmental conditions? How long will it take for the ecosystem to bounce back? Once that question is answered, it is of course still a matter of finding affordable solutions to get those stubborn pine trees out of there…

A lodgepole pine seedling just popped up after experimental pine removal, suggesting that recovery of the native vegetation will not be that easy.


García, R. A., Fuentes-Lillo, E., Cavieres, L., Cóbar-Carranza, A. J., Davis, K. T., Naour, M., Lembrechts, J.J. & Pauchard, A. (2023). Pinus contorta Alters Microenvironmental Conditions and Reduces Plant Diversity in Patagonian Ecosystems. Diversity15(3), 320.

The forefront of the Pine invasion, with the Lonquimay-volcano in the background
An impressive Araucaria-tree, looking out at the volcano

Posted in Chile | Tagged , , , , , , , , , | Leave a comment


I started tracking my time at work in detail at the start of my postdoc in 2018, using the amazing app ‘Timeular’. This series of stories provides some insights into postdoc life using that data.

In a postdoc, not everything goes according to plan. In fact, it’s more likely that they won’t! It’s important to realize that that is totally ok. But it’s important to understand that this is perfectly normal and an inherent part of the scientific process. We can try new things, experiment, make changes, backtrack, change direction. We can fail!

I know he academic climate of recent decades has not been forgiving of failure, but it’s a crucial and valuable aspect of scientific discovery. After all, if success was guaranteed, would it still be considered true science?

Through my time tracking practices, I now have a clear understanding of the amount of time I have spent on ‘failed’ projects – those that I invested hours into but never got published. Note that this is of course just one type of failure and does not include rejected proposals, failed experiments with published negative results, or the countless micro-failures encountered along the way. To give a visual representation, I created a plot of the 35 most time-consuming papers of my PhD.

Ranking of my 35 most time-consuming papers, coloured by my authorship position, with a border colour for their status. Green borders indicate ongoing papers for which I’m confident we will get them published eventually. Red borders are for cancelled papers – papers that I’m confident will never get published.

Good news first: the largest chunk of my time went towards a paper that actually got published! This is our Global maps of soil temperature-paper, a massive effort with a looooong co-author list. However, it’s evident that a significant portion of my time was also dedicated to projects that didn’t see the same success. The list of 35 time-consumers includes seven (7!) cancelled papers and several others that are yet to be published.

One particular project that deserves mention is the cancelled paper ranked second in terms of time invested. It was an ambitious attempt to apply the theoretical concept of higher-order interactions (HOIs) to real-world data. At the time, HOIs were and still are a hot topic, but modeling them correctly proved to be challenging. Most prior attempts were limited to experimental communities, petri dishes, or simple models.

I started modelling on my messy real-world community data (in parallel to a theoretical ecologists who was making data-free models of the same), and solved roadblock after roadblock. Our goal was to confirm the theory through real-world findings, and we worked tirelessly to overcome each obstacle. Despite these efforts, the limitations of the data became increasingly apparent and the impact of methodological decisions was more noticeable. Nevertheless, we completed a manuscript with a story we were confident about and submitted it to our first high-impact journal.

However, the manuscript faced rejection after rejection, luckily with constructive feedback from reviewers. We took their comments into account and worked to make the manuscript better and clearer, highlighting more and more of the unearthed methodological limitations up front. Despite these efforts, the limitations became increasingly difficult to ignore and started to overshadow the findings that I first had been so proud of. After several rejections, we ultimately made the difficult decision to cancel the project, recognizing that we couldn’t get a good grip on higher-order interactions (HOIs) with this messy data. It was a failure.

The list contains other failures.

The list of failures also includes valuable learning experiences. For instance, there were some engaging master’s theses that I invested a lot of time in, but the students had to leave before the manuscript was finished and I no longer had the capacity or expertise to complete them. Another paper that I was enthusiastic about got overtaken by a new one with a more sophisticated methodology, while a dataset that didn’t fit the original research question eventually found use for a different purpose. I also invested a lot of effort into some analyses, only to discover that they would require even more work and were not aligned with what I had promised to the funders.

Although these projects may not have ended in publication, they are not true failures. I learned a lot from each of them and some of that knowledge has, and will continue to, inform my future work in different ways. While the “publish or perish” mentality is prevalent in the scientific community, I firmly believe that the real value of science lies in the learning. Publishing is a great way to share your learning with others, but not all learning has to be public. Personal growth as a scientist and a person is equally important and even if it’s not reflected on your CV, it will benefit you in the long run. I hope this story will encourage you to embrace failures in your own scientific journey.

Posted in Science | Tagged , , , | Leave a comment

Exotic plant species thrive at high(er) elevations

Sometimes one needs patience to answer a research question. Lots of it. The Mountain Invasion Research Network (MIREN) already asked itself this important question back in 2006: how fast are non-native species travelling uphill along mountain roads? Now it’s 2023, and for the first time we have an answer to this, thanks to long-term vegetation monitoring by a team of researchers across the globe, and the work of MIREN master-turned-PhD candidate Evelin Iseli, whose work now got published in Nature Ecology & Evolution (!). What follows is the English translation of the press release by our university. The paper itself can be found here!

Suppose you put your hiking boots in your backpack, fly to another continent and go hiking in the mountains. Chances are that you may find that seeds of local vegetation travelled the whole way with you in the mud on the soles of your shoes. If these fall off your shoe abroad, an alien plant may sprout where that seed has fallen. Thus, without realising it, you contribute to the spread of non-native plant species.

Moving uphill

Ecologists from the global MIREN-network found that the number of non-native plant species in mountain areas around the world has significantly increased in the past decade. Until now, alien plant species were advancing less in mountains compared to their increase at lower elevations. But due to climate warming on the one hand and increasing human influence at high elevations on the other, it now appears that non-native plants in mountains are also advancing steadily uphill.

The number of non-native species increased by 16% in mountain areas.

“Although the presence of native species in mountains is relatively well documented, long-term studies of alien species in mountain areas are very rare,” says Jonas Lembrechts, biologist at UAntwerpen. Lembrechts and his colleagues have therefore been monitoring non-native species along mountain roads since 2007, in 11 mountain areas around the world: in Norway, Switzerland, the Canary Islands, New South Wales, Victoria (Australia), central and southern Chile, India, Hawaii, Montana and Oregon.

“There are big differences in the speed of the invasion, but the general increase is unmistakable,” says Lembrechts. The study of the 11 mountain regions worldwide shows an increase in the number of alien species by as much as 16% over the past decade.

Mainly European plant species

Moreover, in 10 of the 11 regions studied, the scientists found the alien species at significantly higher altitudes than ten or even just five years ago. Moving to higher altitudes to follow their preferred climate is a well-known strategy for plants to defend themselves against climate change. Only, the rate at which alien species are climbing upwards is higher than if climate alone were the culprit.

“Europe is the largest exporter of exotic plants to mountainous regions worldwide, says Jonas Lembrechts. Left: Trifolium pratense from Western Europe in the Norwegian Scandes. Right: the European Taraxacum officinale in the Chilean mountains.

“Exotic species often enter new regions through the lowlands, where most of the people are,” says Lembrechts. “From there, they find their way to the mountains. But with a little help from humans, their spread can sometimes be lightning-fast, especially along mountain roads and trails.”

Off balance

Often these are then also European plant species, research shows. “Europe is currently by far the biggest exporter of exotic plants to mountain areas worldwide,” Lembrechts explains. “Not so strange, when you consider that in recent centuries it was also mainly Europeans who started visiting mountain areas on other continents, for tourist and commercial purposes.”

However, this is not good news. “Mountain nature is often very fragile,” says Lembrechts. “Alien plant species can threaten or drive out native species, which are important in the local ecosystem, throwing the system out of balance.”

Posted in Science | Tagged , , , , , , | Leave a comment

The mystery of the Dark and Light Beetles on Possession Island

New paper out! Espel, D.; Coux, C.; Pertierra, L.R.; Eymar-Dauphin, P.; Lembrechts, J.J.; Renault, D. Functional Niche Partitioning Occurs over Body Size but Not Nutrient Reserves nor Melanism in a Polar Carabid Beetle along an Altitudinal Gradient. Insects 2023, 14, 123.

The southern Indian Ocean is home to the little known archipelago of Crozet. Despite its harsh weather and lack of substantial human presence, the island is a haven for penguins and elephant seals. Among the island’s inhabitants is a seemingly ordinary beetle, the Amblystogenium pacificum. It crawls over and under the rocks, hunting for smaller things to eat, and just lives his normal beetly life. There is just one thing with this beetle that sparked the interest of the (unusually persistent colony of) French scientists on the island: there are two colour versions of it. A light and a dark one.

Star of the show: the endemic Carabid beetle Amblystogenium pacificum

Now, we wouldn’t be scientists if we didn’t want to dig deeper into this.

Scientists have proposed several hypotheses to explain this phenomenon, including Gloger’s rule, which states that darker coloration is a common response among insects exposed to cold conditions. If Gloger’s rule were at play, we would expect to see a fitness advantage in the darker insects when it’s colder. However, it’s rarely that simple in ecology. It’s worth noting that previous studies have observed that the proportion of dark beetles increases by about 8% for every 100 meters in altitude on the island. This results in a clear distinction in the spatial distribution of the two morphotypes. More recent observations made in fellfield habitats have reported that the proportion of brown to black beetles ranges from a 2:1 ratio of brown insects at low altitudes to a 2:1 ratio of black adults at higher altitudes. This further supports the idea that Gloger’s rule may be at play. But as scientists, we can never jump to conclusions too quickly, and we must always keep an open mind to other possibilities.

Find the beetle, happily running across a soft ‘moss forest’. Picture by Diane Espel

Nevertheless, there were both dark and light individuals across the entire elevation gradient on the island. This raises the question of whether the dark beetles fare better at higher elevations (in terms of being bigger, having more nutrient or lipid reserves, etc.) and vice versa.

However, there are other rules that come into play, such as Bergmann’s rule, which states that insects tend to get larger as the temperature gets colder. This is because larger body sizes in endothermic species often correspond to a smaller surface area to volume ratio and reduced heat dispersion in colder climates. Additionally, there is the rule of sexual size dimorphism, which states that female insects are typically larger than males.

So, how does all of this play out on our windy island? The good news is that the elevation (and thus climate) gradient is responsible for many trait differences among the beetles. However, it turns out that coloration does not seem to be a major factor in determining the performance of the beetles. Bergmann’s rule does appear to be at play, as elevation does seem to boost beetle body size (although at the very top of the mountain, the extremely harsh conditions have made them smaller again). Sexual dimorphism is also present, with females having more lipid and sugar reserves (which is pretty clever of them, if you ask me).

Body size as a function of altitude for dark (blue) versus light (green) male (dashed) versus female (full line) beetles. Elevation clearly affects body size, but with virtually no difference between the two colorations or even genders.

However, a so-called ‘functional hypervolume analysis’ did not show clear niche partitioning of the insects along the studied altitudinal gradient, and we had to conclude that niche partitioning was happening for body sizes rather than coloration types.

In conclusion, the mystery of the dark and light beetles on Crozet Island remains unsolved. The absence of clear patterns in the relationship between temperature and size highlights the complexity of the interactions between insects and their environment. Factors such as low temperatures and limited resources at higher altitudes likely play a role in shaping the beetles’ functional traits. But hey, isn’t that what science is all about? Asking questions and trying to find answers, even if they’re not always easy to come by. So let’s just say, the adventure continues!

Posted in Antarctica | Tagged , , , , , , , | Leave a comment