The 3D lab

An injection of mountain views

Posted on July 7, 2022 by lembrechtsjonas

I got to spend a bit under a week in the city of Davos, in the Swiss Alps, last week (more on the what and why here!). With such a backdrop for a conference, we decided that an early morning trip into the depths of the Alps would be a good way to prepare for more scientific discussions.

View from the Flüelapass – close to Davos

And did that not disappoint! The Alps are truly stunning in early summer, with their fields of flowers, stunning views and picturesque villages.

I quickly realized that I hadn’t seen enough mountains recently. As my research has increasingly been moving into the computer and out of the field, it was getting increasingly rare that I saw the mountains with my own eyes.

So this post is here just to shamelessly plug in some mountain views.

Posted in Switzerland | Tagged Davos, Ecology, Hiking, Mountains, Nature, Science | 2 Comments

Beyond the trailside

Posted on July 4, 2022 by lembrechtsjonas

It is a question not too often asked: what is the impact of hiking trails on the vegetation they cross? In a series of observational studies in mountain regions across the globe with the Mountain Invasion Research Network, we are trying to tease these impacts apart.

Part of the MIREN team in Mendoza surveying the dry steppe vegetation

In a recent study, led by the MIREN team from Mendoza, we show what these trails do with the surrounding vegetation in the dry Argentinean Andes. As so often, we found a positive effect of trails on non-native species presence, although surprisingly little impact on richness and cover was found. In contrast, the presence of livestock – assessed simply by counting their dung – had a positive effect on non-native presence, richness, ánd cover.

Lead author Lisi monitoring vegetation on a breathtaking mountain backdrop

Additionally, the typical decline of non-native species with elevation was observed: the higher one goes into the mountains, the fewer non-natives are found. Nevertheless, even the highest elevations were not entirely free of non-native species, with the omnipresent Cerastium arvense and Taraxacum officinale occurring all the way up to 3500 m a.s.l.

The native vegetation of the dry Argentinian Andes includes this fabulous ‘mandala-shaped’ Viola species

The conclusion here is rather worrying: the dry Andes vegetation – with its patches of bare soil under protective shrub canopies that facilitate establishment – are relatively vulnerable for non-native plant species expansion away from the trail into the natural vegetation. This effect is strengthened by the intensive use of the landscape by livestock, which rarely sticks to the trail and might spread non-natives even more rapidly away from the trails. With the more than 40 non-native plant species identified in the system, it is clear that the effect of trails here reaches significantly further into the mountain vegetation than the mere imprint of footsteps.

Touristic activities such as horseback riding can mean a significant boost for the spread of non-native plant species in the region

Reference: Alvarez, M. A., Barros, A. A., Vázquez, D. P., Bonjour, L. D. J., Lembrechts, J. J., Wedegärtner, R. E., & Aschero, V. (2022). Hiking and livestock favor non-native plants in the high Andes. Biological Invasions, 1-14.

Posted in Argentina | Tagged Andes, Global change, Hiking, Mountains, Nature, Nature photography, Plant invasions, Plants, Travel, Vegetation | Leave a comment

To save our world’s biodiversity

Posted on June 19, 2022 by lembrechtsjonas

Today I will be presenting our SoilTemp project at the World Biodiversity Forum in Davos, Switzerland. That place might ring a bell from many a global convention, and the conference name even sounds familiar to the World Economic Forum hosted here. In fact, we are here with a same ambitious goal: bringing together some of the worlds’ experts on biodiversity towards a globally coordinated effort to save as much of it as we can.

View of Davos and – for those who know where to look – its conference center

High ambitions, for sure, but high stakes as well.

An important line of thought throughout the conference, however, is that there is surprisingly much about the sheer numbers of biodiversity that we simply don’t know yet. Especially in remote areas like mountains, and for more ‘obscure’ organisms like soil micro-organisms, we simply do not know yet what is out there, let alone how much of it we are loosing as a result of global change.

Rampion flower in a trailside in the Swiss Alps close to Davos, proudly reminding us what a wonderful biodiversity we can find in this world.

The good news is that this issue is more and more being voiced, and global efforts to monitor, map and predict global biodiversity are increasingly popping up. Many great examples of those were presented here this week.

Tomorrow, I will be showing how I think our work with SoilTemp can help in that regard: we are working hard to provide the necessary climatic baseline data to aid that mapping and predicting. Indeed, without good, accurate and most importantly relevant climate data – and all of that is also still rather patchy across the globe – it is even harder to get an idea of the fate of our worlds’ biodiversity.

For those in Davos, very much welcome to my talk at 16h15!

Campanula flower stubbornly holding on to the rocks of a road tunnel. Anthropogenic pressures are seriously threatening biodiversity, but there is still an awful lot to fight for!

Posted in Switzerland | Tagged Biodiversity, climate change, Global change, Hiking, Mountains, Nature, Outdoors, Plants, WBF2022 | Leave a comment

Trampling to save mountain plant diversity?

Posted on June 13, 2022 by lembrechtsjonas

By Ronja Wedegärtner and Jonas Lembrechts

What do you think about when you follow a hiking path up to the nearest mountain peak? When not thinking about the next chocolate break or the view, I spend my time thinking about ways that the trail that I am walking along might change the vegetation.

As I walk up I am passing through different vegetation types. First, the last meters of mountain forest before entering a zone of willow shrubs, followed by a mosaic of low dwarf shrub tundra and alpine meadows. Up on the peak, the vegetation is sparse and close to the ground.

The fact that trail hiking locally affects mountain vegetation is rather obvious. How exactly the vegetation reacts to this persistent trampling, that has up till now however been surprisingly unknown.

Climate is considered the most important driver of where species grow at broader scales. How could those distribution patterns be changed by trails? Well, seeds can stick to boots and clothes and trampling on and along the trail can create gaps in the vegetation that might allow seeds to grow and establish. Alpine plants are considered especially vulnerable to new neighbor plants that might be moved in by hikers from the vegetation at lower zones. On the other hand, alpine species CAN grow in lower elevation zones – just think about those alpine plants thriving in lowland rock gardens. The climate is suitable for them, but the neighboring lowland plants are most often what hampers their lowland success: When they have to compete with faster growing lowland plants for light and nutrients, alpine species are usually outcompeted. When we remove those neighbors along trails by trampling on them, this could potentially improve alpine species chances in such locations?

With this in mind we surveyed almost 200 transects along 16 hiking trails in two popular hiking areas (Dovrefjell in Norway and Abisko, Sweden) and compared which species we found in trailsides and which in the vegetation away from trails. We identified all plant species and measured how disturbed the plots were.

We surveyed the vegetation along 16 hiking trails in the Scandinavian mountains of Abisko (Sweden) and Dovrefjell (Norway) to pinpoint the effects of hiking trails on the unique vegetation of those systems. The study is now published in the journal *Diversity and Distributions.*

Interestingly, we found a median of 4 plant species more in trailside plots than in those away from the trails, an average increase in diversity of 24%.

A simple figure but with important implications: trails have a higher plant species richness than the adjacent interior vegetation. A positive effect of disturbance on vegetation, perhaps a bit counter-intuitive to most?

Based on our more than 11000 species observations and a unique high-resolution climate data, we examined in which climate we found species along trails and away from them (their realized climatic niches) and checked if these niches had shifted along the trails.

*Lead author Ronja immersed in dense willow shrubs along a mountain trail. Picture: I. Janssens.*

We found that alpine species’ distributions shifted towards warmer locations along trails and that more species’ niches overlapped in trailsides – creating greater richness. As such, trails seemed to create interesting opportunities for range expansion for a variety of species.

Importantly, trampling can create space for alpine plants and may help them persist in a changing climate. But we need to consider trails in context: disturbances may also destroy rare communities or rare and trampling-sensitive species.

So, think where you walk when you are next hiking in the mountains and maybe have a little look around for yourself – do you see more or different species along the trail than away from it?

Reference:

Wedegärtner, R. E., Lembrechts, J. J., van der Wal, R., Barros, A., Chauvin, A., Janssens, I., & Graae, B. J. (2022). Hiking trails shift plant species’ realized climatic niches and locally increase species richness. Diversity and Distributions. https://doi.org/10.1111/ddi.13552

Posted in Norway, Sweden | Tagged Global change, Hiking, Mountains, Nature, Outdoors, Plants, Scandinavia, Vegetation | Leave a comment

The photobomber

Posted on June 8, 2022 by lembrechtsjonas

Now here is a little – and rather easy perhaps for most of those who follow me – botanical riddle: which tree has photobombed virtually all of my holiday pictures of Kotor, Montenegro?

Let me know in the comments if you know!

The Church of our Lady of Remedy on the mountain side in Kotor, Montenegro, flanked by a very characteristic tree

A cat in the hills above the ‘city of cats’, surrounded again by our by now very recognizable tree

Sprouts of the same tree, which followed us all the way to the Acropolis in Athens, Greece

Posted in Montenegro | Tagged Global change, Invasive species, Kotor, Nature, Outdoors, Plants, Travel, Trees | 5 Comments

The energy balance of a leaf

Posted on May 12, 2022 by lembrechtsjonas

I am currently co-teaching the course on ‘environmental biophysics’ to our ecology masters, a largely theoretical course in which students get to know the physical equations behind ecology and the interaction between organisms and their environment. Besides this formula-juggling, the course contains a very nice little practicum which I inherited from my predecessors, which I wanted to share.

The goal is to calculate the full energy balance of a leaf: what kinds of energy are coming in, and which ones are going out again? Then, we go on an ‘excursion’ two meters out of the classroom door, take some real leaves and try to measure the necessary parameters to calculate that energy balance in real life.

Measuring the temperature of three ivy leaves, suspended in the air to simulate ‘normal’ conditions.

This involves a lot of environmental measurements: students measure air temperature, soil temperature, temperatures of the sky, short-wave radiation, wind speed and relative humidity, all these parameters who define the environment of a leaf and thus how it will regulate its energy.

Then of course, pretty important, they also measure the temperature of the surface of the leaf, which in itself relates to all these parameters but also to how well the leaf can regulate its temperatures. That temperature regulation works through two processes: energy loss through transpiration (water loss), and heat loss related to differences in temperature between leaf and environment.

Measuring leaf temperature (white pants), air temperature and wind speed (grey pants) and meticulously writing things down (jeans)

To get a good grip on those different parameters and how easy energy can be exchanged between a leaf and its environment (the so-called conductance of the leaf and its boundary layer), we did a little experiment: next to a control leaf, we had one leaf that we sprayed entirely wet. This situation greatly facilitates the transpiration of water, as now the air-water boundary is not inside the leave (forcing water vapour to go through the small stomata), yet on the outside of the leaf. The result? Significant multi-degree drop of temperature far below air temperature even (we had examples of air temperature at 23°C, and watered leaf temperature at 16°C!).

Additionally, we sprayed one leaf with ‘wilt-pruf’, a resin-based liquid that seals the stomata and thus effectively prevents any water loss. It’s traditionally used in horticulture when you want to prevent a vulnerable plant from loosing water, but here it served another purpose: sealing the stomata removes the transpiration process from the equation entirely. The result now? Take a second to think it through…

Measuring incoming shortwave radiation (device on the right). The ventilators are used to dry the resin-coated leaves.

Indeed, the leaf should start heating up, as it can’t loose energy through water loss anymore! This turned out to be hard to replicate in the field, as it is strongly dependent on weather conditions, wind speed and the question if stomata were open in the first place. Nevertheless, we managed to heat up a leaf 1°C as compared to the control this way!

It took us till we moved to a spot with low wind speed (enforced by wind screens left and right, resulting in a drop in wind from ~2 to 0.4 m/s) before we could successfully get the resin-covered leaf to heat up

So what’s the take home message of all of this? To me, it is that, indeed, you can describe the living world with mathematical equations. Nevertheless, the real world gets rapidly too complex to keep track of the formulas in it, which is why ecology so often works by proxy (and so often has strong noise in the data). An important piece of fundamental knowledge for aspiring ecologists, I would say!