Plant species are on the move, and it is us humans who are moving them

Today, I am finally defending the results of all these years of hard work. For those who cannot join me in the celebrations at the University of Antwerp, here is – in short – the message I want to tell the world.

Garden angelica flanking mountain road

Angelica archangelica along mountain road in the northern Scandes, Norway

Human actions are having a significant impact on the distribution of plant species, and locally even more so than the warming climate. It is the surprising outcome of the PhD-thesis from University of Antwerp-based Jonas Lembrechts, who is studying plant species distributions in cold-climate mountain regions.

Yes, the warming climate is shifting the distribution of plant species poleward and to higher elevations, but our actions are causing even more rapid and structural changes to where species can be found. In his PhD, Lembrechts showed how humans are helping non-native species to invade mountain regions: “Humans are taking non-native plant species with them all over the world, introducing them to other mountain regions. Once there, these species can profit from human structures like mountain roads to move rapidly to higher elevations,” Lembrechts explains.

But it is not only new species who hitchhike on our mountain roads; native plant species use them as well. “I discovered that mountain roads host busy plant traffic from native species as well,” says Lembrechts. “The local environmental conditions in roadsides help many native species on their way to the top, and alpine species even use them to move downhill.” He indeed uncovered important heterogeneity in local conditions that had largely been ignored in the assessment of species distributions: local climate and soil conditions – crucial to plants – can often vary more on a scale of centimeters to meters than across a whole elevation gradient. And human disturbance is a crucial driver of such heterogeneity.

19150984736_b5329369ab_o

Mountain roads – here in the Chilean Andes – and other anthropogenic disturbances have a large effect on the local environment, and consequently on regional plant species distributions.

Anthropogenic disturbances like these mountain roads thus help plant species to move hundreds of meters up and own the mountains, a magnitude of ten more than they have moved due to climate change. These results suggests that we are largely underestimating the direct effects humans have on the distribution of species. That is why Lembrechts warns: “climate warming is having a large – and accelerating – effect on the distribution of species globally, but it should not let us underestimate the direct effect of human disturbance locally.” For mountain conservation, it is crucial to concentrate human presence: urge tourists to stay on the trails, and leave our remaining pristine mountain nature as undisturbed as possible. Only then, we can give the mountain vegetation the necessary room to deal with climate change itself.

Posted in Science | Tagged , , , , , , , , , , | 8 Comments

Anticipation

26495248807_18cb44a8b4_o

Forsythia

The much-anticipated spring of 2018 finally made it to Belgium!

27495288128_52ab427b54_o

Magnolia

Not only because I have been craving to see my beloved plants resprouting, after a long winter of being ‘green-deprived’, but more importantly because this spring I will finally defend my PhD.

41366730411_47b4c2c5b3_o

Rosa

Today, I officially submitted the final version of the thesis document to both the jury and the printing press, and I can tell you I am more than proud of the final product: 226 pages summarizing 5 years of thinking.

40471358585_efc1651d50_o

Carpinus betulus

Now I have a surprisingly large chunk of time on my hand, with for once no major deadline on the horizon (if we ignore the public defence at the end of the month). Spring thus also brings the freedom to dive into my favourite scientific topics for the future, and that feeling of choice is almost as beautiful as the delicate flowers in these pictures.

27495300708_c1de204065_o

Magnolia

Posted in Belgium | Tagged , , , , , , , , , , | 2 Comments

Matching the plant with the environment: what makes invasive plant species so successful?

Scientists have been wondering for a long time why some exotic species become invasive while others do not. A new paper we just published on invasive and non-invasive plant species in Belgium reveals that the answer should be sought at the smallest scale. The authors, a team lead by ecologists from the University of Antwerp, indeed showed that there is a lot of variation in conditions at the local scale, and that each different habitat favors different traits in the exotic species. The exercise revealed many of the standard culprits that make habitats vulnerable (like temperature, light availability, native plant species diversity and soil fertility) and non-natives successful (like plant size, photosynthesis ability and nutrient status), yet invasive species were much better at matching their traits with the environment at the local scale than their non-invasive counterparts. Most invasive species indeed managed to produce many more seeds than the non-invasive species, and that even in habitats normally considered less easy to invade, as long as they locally had the correct trait arsenal to deal with these aversive conditions.

Impatiens

Invasive plant species, like this Impatiens glandulifera (Himalayan balsam) in Belgium, often produce many more seeds than their non-invasive counterparts, yet their invasive success largely depends on finding the perfect match between their own traits and the local site conditions.

This shows that the fight between invasive plants and the native vegetation is likely to be won at the smallest scale, with invasive plants cherry-picking sites that best match their characteristics. Unfortunately, it also means that predicting the invasive success of plant species did not become any easier. Yes, exotic plant species with a higher seed production are much more likely to be invasive, yet this seed production itself is at the small scale highly influenced by the match between both habitat conditions and the other traits of the plants. And as the study shows, this local match-making often has some surprises up its sleeve.

 

Fallopia

Fallopia japonica (Japanese knotweed) has been a highly successful invasive species in Europe, partly due to its flexible adaptation to different environmental conditions.

Reference

Lembrechts JJ, Rossi E, Milbau A, Nijs I (2018). Habitat properties and plant traits interact as drivers of non-native plant species fitness at the local scale. Ecology and evolution.

Posted in Belgium, Science | Tagged , , , , , , , , | 2 Comments

Spring

41023600022_bd47933320_o

Fumaria officinalis on a wall in Portugal’s city of Évora.

Spring is on its way, I promise! I went to Portugal to check it out for you myself. If you want to know why I was there, check out my previous post.

41065960041_b23c4690c6_o

Silene colorata

Even that far south, spring seemed to be slightly later than usual, yet we were luckily enough to have some warm, sunny days, with the first flowers springing up everywhere.

41023564262_5fd19e6f28_o

The rest of the European continent will soon follow, I hope. And with that in mind, we started preparing for summer, and the upcoming field season, as that is what summer is for.

41023572612_b422aa3c8a_o

Silene colorata

As always, we have some awesome plans for the coming summer. And this year, they are bigger than ever, so stay tuned for what is coming, cause ‘On Top of the World’ is truly gearing up!

 

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

Climate change biogeography

There are several ways in which one can tackle climate change and its effects on our world. Biogeographers are approaching the issue via one of its core fundaments: how is climate change affecting the distribution of all living things on earth. And they are doing that en mass.

41065776821_e72fa917bb_o

The University of Evora in Portugal, which kindly welcomed up to 300 biogeographers for a week of cutting-edge scientific discussion

I had the honour to be present at a gathering of biogeographers in the beautiful ancient city of Évora in Portugal, where the International Biogeography Society invited up to 300 scientists to discuss the current state of our knowledge on the impact of climate change on species distributions. Such a gathering is bound to provide some interesting insights, and I’d like to take this opportunity to summarize a few, in between these visual impressions of the hosting city.

40356846104_4826e92279_o

Praça do Giraldo – Giraldo Square – in the city center of Évora

The meeting looked at climate change from three points of view: the past, the present and the future. The first important insights thus came from thousands to millions of years ago: paleobiogeographers are using the response of species to past cycles of climate change as a reference of what could happen now. They showed us rapid distribution changes, flexibility in morphological changes and important speciation. Yet we also learned that often enough, things only start going wrong when humans appear on the scene.

26194884757_9c44fbcdae_o

The ‘Igreja Sao Joao Evangelista’ as seen through the ruins of the Roman temple of Évora

With rapid climate change happening right beneath our eyes, its effects on species distributions are being observed in the very present as well. In that regard, mountains turn out an important case study: with their environmental gradients over a short distance, it is there that shifts in species distributions first become visible. Again, however, the direct impact of humans cannot be ignored: the most rapid upward shifts we observe now are often those of non-native species profiting from an increasing human pressure on mountains.

At the same time, we saw how native species are often lagging behind climate change, while even unexpected downward range shifts are being observed. Overall, current distribution changes thus make one thing very clear: we are evolving towards novel combinations of species, which have never before lived together, and we far from understand all these novel interactions yet.

41065820551_5d4100c03a_o

Little archer tower on a corner of the city walls of Évora

Finally, we shifted our attention to the future, highlighting some of the most important benefits of the biogeographical approach to climate change: we are evolving towards increasingly reliable predictive models of species distributions. Even though several technical issues still need to be tackled, the field is evolving rapidly. We can now even start including biotic interactions in our models to get a better idea of how the novel ecosystems will function, and we are increasing our understanding of evolution and its legacy effects.

41065780781_20d258498e_o

The hosting University of Évora

In short: climate is changing rapidly at the moment indeed, but the speed at which biogeography is evolving is astonishing as well, and therewith comes a growing understanding of what species distributions are and will be doing. And that rapid growth is a big accomplishment for a research field that will soon celebrate the 250th birthday of one of its key founders, Alexander von Humboldt: old, but relevant as ever.

Read more about the meeting on the blog of Nature Ecology & Evolution or in this post.

 

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

Paleo-patterns

DSC_8235

The ruins of the Roman temple in Evora, Portugal

This week, I joined an army of far over 200 biogeographers at the conference of the International Biogeographic Society in Evora, Portugal. Biogeowhat, you might ask? Well, biogeography is the study of the distribution of species, in the past, the present and the future.

DSC_8381

The aquaduct of Evora

Most of our own work fits that definition, as we are studying what drives plant species distribution in mountains. While I focus mainly on the present, there is this whole branch of paleobiogeography that I only really discovered here. Studies on the extinction of megasharks, on the effects of past climate change, or on the impact of thousand-year-old effects on the current distributions of species, it almost feels like an art how these paleo-people can find such intriguing patterns in such scarce and long-buried data.

DSC_8227

The cathedral of Evora

Cause pattern-finding, that’s the true skill of a biogeographer. We often work with large datasets, at a global or continental scale, linking whatever distribution data we have to environmental drivers like climate and land use (change). There is a lot of advanced statistical modelling involved as well, turning the artform even more into magic. But for a paleobiogeographer, this data is even harder to come by. They rely on a tooth or a jawbone or the identification of plant pollen, yet can still tell you that climate is driving species size, and which direction species have travelled to cope with changes in this climate.

DSC_8203

These studies of the past are teaching us a lot about the present as well, what the current global changes will do to our species distributions. I did learn a lot about adaptation, for example: the notion that many species not only move when climate changes, but that they also have a certain flexibility to adapt, either just as an individual or genetically. And that’s why I really start liking paleobiogeography.

(Pictures of patterns in the old city of Evora more or less related – as pattern-searching is our life)

 

Posted in General, Portugal | Tagged , , , , , , , , | 1 Comment