Micro moisture

For a long time, I have been arguing that we should focus on the micro-environment to understand where plants live, and where they will be going in a future with a changing climate. Studying the micro-environment experienced by plants however creates some interesting challenges. The more detail you want, and the closer you want to get to your study species, the more measurements you need to make. On a spatial scale, that is relatively easy to do: you can just put out a whole lot of sensors in the landscape.


Yet there is an often forgotten part to the microscale that is harder to measure: the temporal variation. You could measure the temperature on a thousand spots in the landscape, yet if you can only do this once (or even a few times), your data is virtually useless.


For temperatures, we have some pretty amazing tools to deal with both spatial and temporal microvariation. We have thermal cameras for the finest spatial resolution, and we can even use them to make stop motion movies to capture temporal variation. And we have (relatively) cheap temperature sensors (like the iButtons I wrote about earlier) that can be left outside for a whole year to satisfyingly cover the spatial scale.


Measuring moisture on a small scale turns out surprisingly complicated

For the measurement of soil moisture, the story is surprisingly entirely different. Detailed scanning, like we would do with a thermal camera, is currently hardly impossible for a reasonable price. Cheap sensors that trustworthy measure the soil moisture over time, without complicated wires and data logging issues, is also still lacking. One of the main issues is that the available water strongly depends on the soil type: water in clay is much harder to extract by a plant than water in a sandy soil, for example. It is thus still a search for solutions.

Yet these solutions are on the way, and scientists are showing their most creative side to tackle this issue: exotic sounding methods like using cosmic-ray neutrons, or through GPS-signals or even temperature measurements are rapidly gaining accuracy. Before I loose all my readers to these foreign words, I will just refer everybody on a search for good methods to this paper from Oschner et al. (2013).


Oschner et al. (2013). State of the Art in Large-Scale Soil Moisture Monitoring. Soil Sci. Soc. Am. J.

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The holiday lens


The photographing ecologist got an update of his photographing gear, and that is amazing news! Most notoriously, I now got a 18-300 mm lens, a lens famously called a ‘holiday lens’, as it is perfectly suited for holiday trips where you do not want to take several lenses.


This holiday lens is the perfect allround lens, with an incredible range: it can both handle the wide angle ànd the close-up, all of that in just one twitch of the wheel.


While the critics say that you give in in quality if you want to have the whole range in one lens, this extreme flexibility is a blessing for a photographing ecologist (details of what that is, can be found here). As in my job, photography is only secondary. To let the work come first and still achieve breath-taking pictures that tell a story, speed and flexibility are key, and this 18-300 mm allows exactly that.


As the first trials show, the options are promising. Yes, the quality might not be as perfect as in the more expensive – less agile alternatives, but these minor details, the difference between very good and slightly better, do not weigh up to what the lens can do for me: allowing me to quickly jump from the closest to the furthest.


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An unusual hero

Last week, Hans Rosling died. Who, you might ask, and why mention him? Well, he might have been one of our few statistical heroes, a man who dedicated his life to the spread of knowledge through the correct use of statistics, and to me, that’s enough reason to honour his passing. If you have a spare hour, I strongly recommend you to watch this video of him, as an example:

Trust me, it is worth it. And as soon as he starts talking, you will be hooked, as he was a very gifted speaker; and statistician of course.

The story he tells here is about the world’s population growth, and the population boom we are currently undergoing.


More people live in cities than ever before in human history. Here, London

The best part of the talk is that, even while you think you know the basics of the story (the booming population growth resulting from a time difference between the improvement in health care and the reduction in family size), he can still blow you off your feet.



And what he wants to convince you of in this video narrows down to this: don’t panic! It is not all as bad as it seems. Countries everywhere in the world are evolving, people are fighting their way out of poverty and the average family even has only 2,5 children anymore, even in less wealthy parts of Asia.

Yes, that last value might be surprising, yet it is most certainly true: we have reached – as he calls it – ‘peak child’. There won’t be more children between the age of 0 and 15 anymore in the future, the number will stay constant at 2 billion.


Delft, the Netherlands

But why is the population still growing so tremendously, even if we reached ‘peak child’? In short: pure mathematics. While there are not more children being born anymore, so the population boom is theoretically over, there are still less old people dying, and that will inevitably be the case till we reach a stable world population at 9 billion. So yes, population is still growing tremendously. However, and that is the big surprise that statistics can show us: this population boom is not at all due (anymore) to uncontrolled child births in extremely poor parts of Africa and Asia.



And even though it might still look at first sight like things are rapidly getting out of hand with our little world, Hans Rosling convincingly shows that it is not all as bad as you think. The population growth is fixing itself, and the world is rapidly taking care of extreme poverty as well. Climate change is the next tough issue to tackle, but it is worth it to stay optimistic that we find solutions for that as well. But who is better suited to convince you about that than Hans Rosling himself? The answer is right there in that beautiful piece of video.

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Recently, I have been giving more thoughts to the human influence on nature in our own country. When walking through Flanders, it soon gets obvious that humans are everywhere. Even more, it is clear that the pure, undisturbed nature is gone completely in the region, and has been for many years.


What we have left is a few, scattered patches of half-nature: parks, a few patches of forests, heathlands… A sad notion, indeed. And still, walking through the same Flanders, you can find a lot of potential, if you know where to look.


This knotted willow, for example, on the shore of a little stream close to Mechelen, in the populated center of Flanders. A tree that would not exist without humans, a tree that would never look as stunning without our help. A micro-environment for plants, insects and even birds. It might not be what it was before, but it definitely stands in its own right.

Fruit for thought, for sure. To keep out the depression, at least, and believe in a future where humans and nature can live in harmony. Yet definitely not to  justify further destruction of the nature we have left.

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Global change ecology

Our research center – the excellence center on Global Change Ecology – started its own blog! Unfortunately for the international audience here, the blog is in Dutch, yet it featured my recent article on the difference between climate and weather!





Blinded by a snowball, now as ‘verblind door een sneeuwbal’ on the global change ecology blog


We hope to bring up to date and scientifically supported posts on all factors of global change that are covered in our group: climate change, climate extremes, invasive species, nutrient cycling, habitat fragmentation and many more… As the center on global change ecology is a collaboration between 3 research groups, we have the chance to approach these problems from all possible sides, and advance faster to solutions!

Contributing to the understanding of our changing world, one discovery at a time.

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What I love about winter is how it accentuates the lines in the landscape.


Yet the most important lines of this season are the deadlines, and this January had quite a lot of them.


We submitted two big projects that – if all goes well – could result in major expansion of our research on plant invasions. Throughout the years, we discovered many more things that we do not know yet, and it would mean a lot if we could go on a hunt for the answers.


For now, it just means waiting… When summer is back upon us, the wait will be finally over.


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Blinded by a snowball

There once was this US senator who brought a snowball to the parliament to proof climate  change is not as bad as we wanted him to believe.


A small act, you could even call it a joke, yet it pops up in my mind every time our world is covered in snow and ice. Yes, it is cold, it can even be extremely cold, it can even snow in Spain and the Sahara. But that does not mean climate change is less real.


Being blinded by a bit of snow is a common misconception. The senator with the snowball could do with a look at the video of the man who walks his dog, showing the difference between trend and variation. The happy dog hops around, going left, going right, going straight, sniffing and looking. His trajectory highly unpredictable. Yet, slowly and steadily, he is going towards the upper right corner of the panel. Even though every next step of our little buddy could surprise us, we still now he is going to end up there. And that is because of the owner, the man on a line, the trend line. The dog symbolises the weather, unpredictable in its every move. The owner is the climate, slowly and steadily warming.

We know this is happening. We do not need the absence of snowballs to proof it. You can see it in our longterm data, like this beautiful, yet shocking, timelapse of the worlds temperature from 1880 till now:

More on this one on nasa.gov.

So we should not look at the variation, but at the trend. True. But what if our steady-walking owner is not going in a straight line? He might make some turns as well? And that brings us to another argument of climate change deniers: if we zoom out far enough – let’s say a few thousand or even million years – our owner has been walking all over the place. He has been higher, he has been lower, he has been everywhere.


True. Our climate has seen some variation in the past. Yet we know now that our owner now is climbing an increasingly steep slope. We know that such steep slopes have been extremely disruptive for biodiversity in the past. And we also know that it is our emission of greenhouse gasses that is chasing our guy uphill. Clearly he has been everywhere, but rarely he moves so rapidly, and when he did, it was often catastrophic for live on earth.


Earlier this week I went to a lecture from Jens-Christian Svenning, a scientist from Danmark. He studies longterm effects of climate on biodiversity, and his story is fascinating. He showed that our world is still catching up to climate events from the past, some of them even millions of years ago. The fact that we do not have some species in the Scandinavian mountains that could be there based on where they live in the Alps, or that we do have tons of palm species in the Americas yet relatively few in Africa, it is the result from longterm changes in the climate. This shows how long-lasting the effects of a change in the climate can be. Climate change effects in the past have been big, and their legacy is still felt in the present. Then what to expect from this sudden, massive change in climate that is currently upon us? How far will these effects go? But what this shows most clearly, is that species adjust their distribution to changes in the climate, yet that they are limited in how far they can go.


So yes, the owner is the trend, but that does not mean that the dog does not matter! On the contrary. Extreme weather events, from one year to the next, can have a massive influence on our world. One big frost or drought is sometimes enough to disrupt a whole ecosystem. Indeed, plants and animals do not experience the trend as it is, no, they experience the weather from day to day, often even with small-scale variations over distances of a few meters (or less!).


So, why bother with the owner as it is the dog that is felt in reality? To grasp that, you best check the first video again. Our dog is following the same route as his owner, albeit not directly. We know that the owner/trend will end up at the top right (if nothing changes his path), even when the dog sometimes heads down. Moreover, yet not shown in our little video, we know now that on his way to the top, the dog is getting more and more excited. Climate change is resulting in more extreme weather events, the dog starts to care less about his owner: more ups, more downs, more jumping all around. As it is these ups and downs, these extremes, that are felt by those living on our planet, this obviously creates additional strains on the living world.


So where does this leave us? The smallest scale matters. Yet if the trend is moving upwards, the small scale will follow. More extremes might force the world to adjust rapidly. Yet we know from looking at the past that there is a limit to the adaptability of species. Cross that line, and they are inevitably lost. It leaves us with the conclusion that we should take our climate seriously, and not just throw snowballs and move on.

Want to know more? Check out skepticalscience.com for more common misconceptions about climate change.



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