Let’s track some noise!

Posted on April 3, 2023 by lembrechtsjonas

I am delighted to announce that starting this month, I have taken up a part-time position as a postdoctoral researcher to lead a groundbreaking citizen science project on noise pollution in urban environments. The project is being co-led by the University of Antwerp, which has made citizen science a core mission, building on the resounding success of our “CurieuzeNeuzen” initiatives. This opportunity is a perfect blend of my expertise in large-scale environmental monitoring, citizen science, and the urban context, even though it takes me beyond my ‘ecology’ comfort zone.

Cities, such as Brussels, Belgium, are filled with a myriad of sounds. While it is evident that all these sounds can have deleterious effects on human health and well-being, very little is currently known about the spatial distribution of these sounds. That is where our project comes in!

As it is a part-time position, I can continue to devote the rest of my time to my beloved SoilTemp microclimate projects. Additionally, this opportunity is not only a tremendous source of enthusiasm, but it also provides me with a chance to remain in academia for a while longer, until I find a more long-term perspective.

All in all, this is a pretty exciting and promising new beginning! While I am still contemplating how much I will share about this new role on this website, as it is somewhat beyond my usual topics, I am convinced that I can pique your curiosity about noise and its risks and opportunities in the most complex and captivating ecosystem of all: the city.

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Průhonice 

Posted on March 23, 2023 by lembrechtsjonas

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.

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Virtual SoilTemp symposium

Posted on March 6, 2023 by lembrechtsjonas

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

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

Final program looks as follows:

Monday May 8th (main event)

15h00-15h05 Trickle in – welcome screen
15h05-15h20 SoilTemp overview (Jonas Lembrechts, 12’+3’)
15h20-15h30 SoilTemp database (Rémy Beugnon, 10’+0’)
15h30-15h45 DirtClim (Dave Klinges, 12’+3’)
15h45-16h00 MIRRA: real-time microclimate sensor (Pieter De Frenne, 12’+3’)
16h00-16h15 ForestClim (Stef Haesen, 12’+3’)

16h15-16h25 Break

16h25-16h40 Global soil frreeze/thaw project (Jeremy Johnston, 12’+3’)
16h40-16h45 Soil moisture fluctuations affect forest temperature buffering (Caroline Greiser, 5’+0’)
16h45-17h10 4 community presentations (Robert Weigel, Matej Man, Diana Stralberg, Martin Dovciak, 5’+0’)
16h10-17h20 How to submit your data? (Jonas Lembrechts, 10’+0’)

17h20-17h45 General questions (0’+25’)

Friday May 12th (add-on session)

9h00-9h05 Trickle in – welcome screen
9h05-9h35 SoilTemp overview, database and main projects (Jonas Lembrechts, 25’+5’)
9h35-9h45 How to submit your data (Jonas Lembrechts, 10’+0’)
9h45-10h30 General questions (0’+45’)

Picture by Stijn Van de Vondel

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!

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The impact of the pines

Posted on March 2, 2023 by lembrechtsjonas

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.

Reference

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. Diversity, 15(3), 320.

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

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Failure

Posted on February 8, 2023 by lembrechtsjonas

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.

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Exotic plant species thrive at high(er) elevations

Posted on January 26, 2023 by lembrechtsjonas

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.”

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