A call answered across the globe

Posted on July 9, 2023 by lembrechtsjonas

It’s safe to say that last month’s call for microclimate data for our growing SoilTemp database was a success. Almost two hundred new datasets, ranging from just a few sensors to a whopping 32 thousand per dataset, poured into our new SoilTemp email address. All that for a grand total of….

MORE THAN 50.000 NEW TIME SERIES!

Now, we are putting everything into force to get all that data processed and added to our database. But I already wanted to provide a sneak-peak of the scope of that new data, through this graph of number of time series per country*.

Number of time series per country received during this call for data

The tally contains a total of 53 countries, in itself likely to substantially increase the number of countries we had already in SoilTemp 1.0 (over 70). Maybe at some point, there will not be any comments anymore about our database not being truly global!

Now, there is a ‘little ommission in that previous graph: the new submissions from Belgium (where I am based). There, we made use of an army of citizens to collect that dataset of 32.000 time series mentioned above, an achievement that obviously skews our graph a little bit when added.

Number of time series per country received during this call for data, skewed towards the rather overwhelming submission from Belgium

Now, if you think you have some fantastic data lying around and are sad you missed our deadline, don’t worry! There is a latebreaking deadline on October 20th, for those who are collecting their data over this northern hemispheric summer, and for those who only learn about the initiative now. All data still welcome by then to be included in our upcoming database publication!

*Only for those who followed exactly the submission format, as no further processing has been done, so this is a bit of an underestimation!

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Tundra traits

Posted on July 4, 2023 by lembrechtsjonas

It was summer 2017, the height of my PhD. As always, I spent the longest days above the polar circle, in the north of Scandinavia. We were there to follow up on our long-term vegetation monitoring, in particular this time to do the five-year resurvey of the roads we are tracking there for the Mountain Invasion Research Network. Little did we know that amidst all the data collection, a side project involving leaf harvesting would eventually lead us on an unexpected journey.

The summer of 2017, spend in the eternal sunshine of a sunny northern Scandinavian July, doing what one should do on such an occasion: botanizing!

We also harvested a bunch of leaves, that summer. Our goal? To examine plant traits across various elevations and explore the impact of roadside disturbance on these traits. Our dedicated master student, Amélie, crafted a fascinating thesis, full of intriguing discoveries that unfortunately remained buried in the shadows, as so far too often the case with master theses.

However, our leafy escapades did not go in vain. We decided to contribute our precious data to the Tundra Trait Team-database, led by the indomitable Anne Bjorkman from the University of Gothenburg in Sweden, making them a vital building block for a global dataset of tundra plant traits.

Beautiful leaves – here of Betula pubescens – going under the scanner to assess their size

Now, that global database has resulted in a new and exciting study, freshly published in Nature Communications. The idea was to combine this large database with species distribution data, and hopefully predict which species would emerge as champions or casualties in the increasingly-changing climate of the tundra. The hypothesis was that it would, as one can expect certain kind of species – with certain traits – to benefit disproportionally more or less from changing climatic conditions in the tundra than others. For example, all signs point into the direction that taller plants would increase significantly in cover at the expense of short-stature ones.

Tall plants – here Valeriana sambucifolia – were expected to profit from a warming climate in the tundra, yet the findings do not confirm that hypothesis.

Now, was that a bit of a disappointment! Our initial hypothesis, built upon the pillars of previous literature, proved too simplistic for the complex world of tundra shrubs. Instead of consistent trait responses, we discovered similar values of height, specific leaf area, and seed mass among both range-expanding and contracting tundra shrub species. Mother Nature is known to love her surprises!

Who wins and who looses in a changing tundra is a complex matter. Our paper helps to adjust our expectations in that regard! Photo: Rubus chamaemorus, the cloudberry.

Importantly, projected range shifts will thus not lead to directional shifts in shrub trait composition or variation, as both winner and loser species share relatively similar traits.

As usual, of course, there is plenty of room for improvement. Our study highlights the need to explore other morpho-physiological traits for which sufficient data remains elusive, and to address how demographic processes might mediate tundra shrub range shifts.

Leaves are beautiful, and fun to work with. But perhaps the answer to our question could be found underground! Time to give more prominence to root traits in future global research as well!

In our quest to uncover the future winners and losers of climate change in the mesmerizing tundra biome, we’ve encountered a few unexpected twists and turns. It’s as if these plants are whispering, “Don’t judge a shrub by its leaves!” The observed and projected abundance changes and range shifts will thus interestingly enough not lead to major modifications in shrub trait composition, since winner and loser species share relatively similar traits. So, as a scientist, I’m happy to shout out as a conclusion: “oh boy, is it complicated!”

The tundra is changing, and rapidly, let there not be any doubts about that. Yet, it has been less straightforward to predict how that future tundra vegetation might look than ecological theory suggested.
Warming a cup of tea on the campfire at our hut in the Norwegian mountains in the summer of 2017
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Species on the move

Posted on June 2, 2023 by lembrechtsjonas

‘Species On The Move’: It’s a conference name with a ring to it. Its goal is to bring together scientists and conservationists around the topic of the impact of climate change on species distributions. This third edition was held in a fancy Floridian hotel bordering the Gulf of Mexico, and the topic felt more pressing than ever.

Pretty surrealistic view of the hotel hosting the SOTM-conference, embedded in the mangroves on the coast of the Gulf of Mexico

Corkscrew swamp, with some of the last remaining old cypress forests of Florida, set the scene very well for our conference

For one, the surrounding area in Southwest Florida excellently highlighted some of the main messages of the meeting. Florida is a state packed with wildlife and rare plants but is also a state with an astoundingly rapid expansion of human settlements, with little to no regard for the idea that land may have its limits. As a result, there were turtles in the parking lots, crabs on the road, and manatees in the marina, but also all water drained from the protected marshland surrounded by rapidly expanding human settlements.

Beautiful native green anole lizard, one of the countless animals one can admire in Florida
Urban expansion everywhere! Here another piece of mangrove removed to be turned into a hotel

These obvious human-nature conflicts reminded me of one of the recurring topics of the conference: most of the time, species are NOT moving as predicted based on climate change, and one of the many reasons is that they simply CAN’T. They lack the natural corridors to reach areas with ideal (micro)climatic conditions, as they are locked on tiny islands of nature in an anthropogenic ocean. This issue of connectivity has only recently been revisited in the research on species redistribution (although the problem of connectivity itself is, of course, widely known), as until now we simply lacked the data to test this thoroughly. Together with the whole story of why species are not moving as they ‘should’, a topic that we urgently need to keep working on as a field.

Determined-looking turtle in a parking lot at the edge of a nature reserve
Ibis simply ignoring the beach-goers.
Black vultures feasting on dead fish after a pond dried up. The rainy season was delayed, and drainage doesn’t help, but this annual drying up of ponds – to the delight of vultures – is not that unusual, I understood

A second way in which Florida screams ‘moving species’ at you is through its vast collection of non-native species. I saw a bunch of lizards (and each of them got me excited all over again), but it turned out that many – if not most – were not native to the region. The spread of non-native species is a topic that has obviously been widely discussed in the literature already but, it turns out, largely separated from the ‘species on the move’ literature. There were indeed very few invasion ecologists at the conference, despite the strong overlap in interests! Taking a look at the lessons learned in invasion ecology and how they do and do not apply to the new situation at hand for climate-driven species redistributions would also help us substantially move forward!

Non-native anole showing off its ‘dewlap’

This is just a glimpse of the many important issues that came to light at the conference. Luckily, there was an atmosphere of creative enthusiasm, and I felt like we collectively made six months of progress in a span of mere days. I am confident you will hear more about our achievements in Florida in the near future. And that’s crucial, as species movement is only just gathering speed!

Little crab determined to fight me if I would come any closer. Many species are punching above their weight, but the fight is only getting harder. Conferences like this one are crucial in our search for practical solutions to the problem of moving species that our world faces – and increasingly will face. (Note: there was a lot more talk about solutions than I’m touching upon in this blogpost – but I’ve always been more on the theoretical side myself)

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Does microclimate change move species?

Posted on May 18, 2023 by lembrechtsjonas

With 200 or so we came together, here in the scorching heat and relentless urban expansion of southwest Florida, to talk about ‘species on the move’.

How an unfortunately large part of southwest Florida seems to look nowadays. Imagine the extreme microclimates in these non-habitats!

Global change is pushing species from all sides, forcing them out of their traditional ranges into new ones. With ‘SOTM’ already at its third edition, this issue has only become more urgent. Species range shifts are picking up speed, increasingly moving into uncharted territory, and causing a complicated reshuffling of biodiversity. Yet there is something intriguing about these species range shifts: there are only very few that are tracking climate change as predicted. Many terrestrial species are lagging behind climate change, or even moving in unexpected directions.

Corkscrew swamps and marshland, original Floridan wetlands

It is in this context that I’ll be giving a keynote lecture on Friday on the role of microclimate in the matter, as it seems to be that microclimatic heterogeneity could be taking away a large part of the need for species range shifts: thanks to microclimate, species often have to move only a few kilometers to find the climate conditions they are looking for.

However, these microclimates are also warming! Problem is, we don’t know yet how fast. My work focuses on getting that question answered: how fast is microclimate changing, and how can we best slow down that changing climate?

Forests buffer microclimate. Question is, will they also be able to buffer microclimate change? Strangling fig on a cypress tree in Corkscrew Swamp Sanctuary

For this, we need lots of data! The SoilTemp database is that source of data, and we just launched a massive new call for data. So, if you have microclimate data, consider submitting it to our database! If you’re at the conference and have questions about SoilTemp, data submission, or microclimate in general, I’m organizing an informal session during the coffee break on Friday, at 10h00, in Calusa B!

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An efficient way to obtain soil texture data

Posted on April 27, 2023 by lembrechtsjonas

When we designed our large-scale citizen science project ‘CurieuzeNeuzen in de Tuin’, we soon realized we had a problem on our hands: if we wanted to get an accurate idea of soil temperature and especially soil moisture from our 5000 measurement locations, we needed to have data on local soil conditions, and at least the soil texture.

That was not entirely impossible, we thought, as we had a laser diffraction device in the lab to assess soil fractions that could be used. We just had to ask all citizens to take a soil sample and send it to us. The problem came to the surface when we calculated our time investments: most laser diffraction analyses – at least those we knew of – could handle four samples per hour. And that was at their best behaviour only, excluding errors, cleaning of lenses, replacing of components etc.

Sampling the soil around our ‘garden dagger’

Now, four samples an hour for 5000 samples gives a total of 1250 hours of soil texture analyses, which is 156 days of relentless work, or 8 months of continuous labwork for a lab technician; if not beaten to death halfway through by the extreme dullness of the task at hand.

A delivery to our university of 1276 boxes with soil samples, frankly hammering home the message that this was quite the amount of samples to deal with

It was obvious that we needed a better solution. That solution was found with our colleagues at the Earth and Life Institute of UCLouvain. They had a different way of measuring soil texture, using visible near-infrared spectroscopy. This technique was much faster – in a blink of an eye a soil sample could be scanned.

Laser diffraction involves boiling soil in acid, which is pretty cool at first, but can be rather time-consuming, especially for soils rich in organic material

Spectroscopy works fast, but the results need to be calibrated. For a subset of the data – say 10% – the traditional laser diffraction method still needs to be used, which can then provide you with a calibration curve to identify the fractions of clay, silt, and sand in your sample.

The spectroscopical analysis is as simple as putting a scanner on top of such a dried soil sample and processing the result

In a new paper together with the team at UCLouvain, we now provide a better calibration formula for this spectroscopical analysis, which takes into account one mathematical issue with texture data: the sum of clay, silt and sand is always 100%, so you need to model them together to avoid impossible soils with more (or less) than 100% of volume.

That issue has now been solved and published in the journal ‘Soil and tillage research’. Thanks to this fabulous method, our citizen participants also had to wait only four months to get information on their garden soil texture on their dashboard, a most remarkable achievement they are probably not even aware of.

One enthusiastic citizen – probably largely oblivious of the massive undertaking it would be to get their soil sample analyzed in time.
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Microclimate can save plant species from population migration

Posted on April 24, 2023 by lembrechtsjonas

Global warming would force plant species to move dozens of kilometres north at breakneck speed to still find suitable habitat. “A failure for flora,” was the scientific consensus for a long time. Recent research suggests that such population relocation would not be necessary in many cases. Plants could seek refuge in ‘microrefugia’: oases in the landscape where the climate is relatively cooler than in the surrounding area.

Those who look at the climatology models hold their breath. Global warming is pernicious for greenery in this world. In fact, temperatures would rise so fast that plants would not have the chance to seek cooler places in time.

Although two recent papers in the journal Nature Climate Change outline a less grim prospect. “So-called microrefugia, such as a dense patch of forest where temperatures under the canopy are much lower than in the open areas around it, can provide (temporary) shelter for species fleeing rising temperatures.” explains ecologist Jonas Lembrechts (University of Antwerp). Lembrechts is the author of one of the papers and helped note that so far the consequences have turned out to be less severe than expected. “Thanks to those cooler locations, plants over the last 20 years eventually had to move no more than one km northwards, Maclean and Early calculated, while traditional models indicated another 50 km or so.”

One type of warming is not the other

“The temperature as perceived by plants, close to the ground or under the canopy of a forest, is very different from what we are used to from our weather stations,” Lembrechts explains. For instance, trees form an insulating layer above the forest, and photosynthesis in leaves causes water to evaporate, drawing heat from the environment.

Now it gets really interesting when those microrefugia are not only cooler than their surroundings, but also heat up more slowly. This makes them a buffer against climate change for much longer. “Such slower warming now also appears to be effectively possible,” Lembrechts explains. “For instance, in previous research, we showed that temperatures warm up more slowly in forests than in the surrounding countryside, because the cooling effect of (healthy) forests increases even more when temperatures rise.”

The influence of microclimate. A representation of the rate of microclimate change resulting in species range shifts. Three scenarios are shown: increased urbanization, unchanged land use, and increased forestation. The macroclimate will warm by 2 °C between 2020 and 2040. Each microhabitat may experience a unique rate of warming, ranging from 0 °C to 4 °C per pixel. Increased urbanization accelerates microclimate warming and requires faster species range shifts, while increased forestation slows microclimate warming and may maintain viable species populations. Protecting natural areas and creating new ones, especially in urban settings, is essential. The graph (bottom right) shows microclimate temperature increase variation over the 20-year period in different land-use scenarios (red, yellow, and blue).

Smart nature management as a solution

Such findings show that local nature can play an important role in combating the effects of global warming. At the same time, it is also fragile and human intervention can cause significant damage. Lembrechts: “Cutting down a forest will kill that local air conditioning, resulting in a local rise in temperature. That warming process can be much faster locally than what we expect from global climate change.” As a result, plant species will still have to rush off to cooler places.

But things can be different: smart nature management is able to firmly slow down warming at the local level. “So from nature’s perspective, it is not just about to what extent we can limit climate change by reducing our CO2 emissions, for example,” Lembrechts stresses. “Certainly as important is what we do with our limited green space. If we let it become more and more urbanised, the temperature in the microrefugia will rise much faster than if we bet on more forests, marshes, and other greenery.”

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