The 3D lab

Leaving spring for autumn

Posted on March 15, 2014 by lembrechtsjonas

Spring was getting on full speed last week in Belgium. The first spring flowers were emerging everywhere and it was already warm enough to forget your jacket. It maybe false hope, but spring was in the air!

I tried to absorb as much of the sun as possible, because next week I replace our Belgian spring again for autumn in Punta Arenas, Chile, for a check-up on the seedlings of my experiment.

I had a chance to visit the zoo to join the meerkats for a moment of afternoon sunbathing, before I had to start packing jackets, gloves and warm fleeces. There will be frost already in the highest plots, so I need to be prepared for the worst when I have to work long days sitting on the frozen ground.

Posted in Chile | Tagged Abroad, Adventure, Animals, Fieldwork, Flowers, Meerkats, Punta Arenas, Spring | 4 Comments

Aliens and their way to the top

Posted on March 13, 2014 by lembrechtsjonas

Remember my story about how lowland roadsides are flooded with species that do not belong in the natural system? Remember how these new species could profit from the lower competition when the natural vegetation got destroyed by the process of road building? A lot of these species are well known to Northern Scandinavia, but some of them are not. And this last group deserves our special attention.

A group of true culture-followers. The real roadside species. The ultimate weeds. They followed human development up to the north at one point in time, some decennia or centuries ago. We call them aliens: visitors (and sometimes invaders) from another ‘world’. (But do not let them fool you, because they are just species like our regular white clover!)

What is really curious is how almost all these aliens share the same story. Their invasion always starts in the lowlands, where they got introduced, after which they closely follow roads and human structures up into the mountains. Not too many of them really reach the top, however. We see a progressive drop-out of species on the way, victims to the cold alpine climate (but keep in mind this is a dynamic process, they could still be on their way!). This progressive loss of alien species with elevation got the fancy term ‘directional ecological filtering’ and it also seems to be happening in our subarctic ecosystem. The mountain acts as a filter, only allowing a select group of aliens to the highest elevations, while the weaker ones are filtered out (check the clear decrease in roadside alien richness with elevation as visualized by the black line on the graph).

The question is which skills are needed to sneak through this filter to reach the highest elevations in the mountains. It turns out that all winners of the race to the top follow a similar strategy: they are all generalists, which means they can thrive in a wide range of environments. That makes them different from the vast majority of plants that got adapted for one particular situation. It also makes them incredibly suited for mountain invasion. Mountain invaders have to overcome both lowland and alpine conditions. Strong competitors loom in the lowlands, where conditions are good and fast and efficient growing are the keys. In the highlands, the harsh climate demands stress-tolerant traits to survive the cold: growing slow, staying close to the ground and using resources to fight the harsh conditions.

That is the reason why pure competitive alien species are stuck in the lowlands, while the generalists can follow the road all the way up to the alpine zone. While both know how to handle the intense competition in the lowlands, only the generalists can change their strategy to deal with the totally different alpine conditions from the highlands. And as soon as these villain generalists reach the top, we should foresee major problems, but that will be covered in another post!

This picture clearly shows how the vegetation changes drastically over only a small elevational gradient.

Posted in General | 3 Comments

Kitchen ecology

Posted on March 11, 2014 by lembrechtsjonas

Ecology should not always be about the large scale. Sometimes there is no need to go all the way to Chile or Sweden to find some exciting plants!

I have twenty square centimeters of fantastic ecology right in my kitchen. I am growing some basil herbs, 4 different species in a stylish metal bucket. I see it as a test to check if all my theoretical background provides any support in raising my own kitchen plants.

It made me already very excited to see them germinate so fast. You can see them gain centimeters every week!

Also: what a high germination rate! Almost all of the seeds made it to the seedling phase, so I will have to thin out soon to give the strongest plants more space (we learned here how tough competition would be disastrous for seedlings). I can only hope my seedlings in Chile will turn out to be as successful when I go back there next week!

Posted in General | 1 Comment

My friend robin

Posted on March 8, 2014 by lembrechtsjonas

It is great joy working with playful action of birds behind the office windows.

Although we did not have a cold winter at all, a lot of birds were still very happy with all my extra food. This is my personal favorite: the European robin.

The moment he found out how to balance on the food, he became one of my most common visitors.

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More about roadside vegetation

Posted on March 6, 2014 by lembrechtsjonas

Roadsides host more plant species than the natural vegetation. That is the stunning conclusion I draw in my previous post. While this difference is clear on low elevations, it vanishes as we get higher in the mountains, ending in similar species richness in the alpine zone above the tree line. Surprisingly, as can be seen on the graph, this pattern is the result of a higher diversity of alpine species (dashed grey line, white dots) in the natural vegetation.

Native species richness per plot with elevation. Black lines/dots = roadsides, grey line/dots = intermediate, dashed grey line/white dots = natural vegetation

The alpine zone is a rocky, barren place without trees. That sounds as a bad thing for plants, but it also results in a higher availability of open places. The dominance of mosses and dwarf shrubs like the crowberries I wrote about, is less intense here. More open spots, less competition, more diverse habitats, all kinds of factors that could explain the higher plant diversity visible in the graph. All of this explains the higher species richness on high elevations. But why don’t we have the additional higher species richness here that we saw in the lowland roadsides?

Here is why: the higher amount of species in lowland roadsides comes from a bunch of typical roadside species, mostly highly competitive weeds (e.g. willowweed, see picture). They do not belong in the normal undisturbed subarctic mountains, but typically follow humans, agriculture and the availability of rich soils and mild conditions. This kind of culture followers forms an important part of the lowland roadside vegetation. These species are added on top of the baseline species richness of typical subarctic mountain vegetation. Therefore: higher roadside diversity.

These competitive weeds are rare in the roadsides on high elevations, where conditions are not mild at all. The roadsides there serve more as a refuge for stress-tolerant alpine species, because the difference with the natural alpine vegetation is much smaller: both contain open, low vegetation, with a lot of bare rock and bad protection against harsh weather. Perfect for stress-tolerant plants (like Saxifraga, see picture), a disaster for the competitive kind.

Conclusion: the subarctic mountain road has a much smaller effect on native plants than its lowland counterpart. Lowland roadsides suffer from the invading pressure of competitive weeds, while they serve on high elevations more as a refuge for a wide diversity of alpine species.

You want to know the exact scientific story? Here it is! The story spread in the meantime to the international (scientific) media. Find already one link to the media here.

Posted in Sweden, The research | Tagged Alpine, Ecology, Field ecology, Mountain ecology, Mountains, Plant strategies, Plants, Publication, Research, Roads | 4 Comments

Changes in the mountains

Posted on March 3, 2014 by lembrechtsjonas

Mountains are increasingly important islands of nature in our rapidly changing world. They contain some of the most diverse biodiversity hotspots in the world, have a high aesthetic value and their conservation even has a lot of economic importance. There are countless reasons to be happy that we still can rely on this pure and undisturbed nature.

For now, alpine ecosystems are among the better conserved ecosystems in the world. However, we should not be too satisfied with that conclusion. While you are reading this, the countless mountain resources get increasingly exploited. How our beloved mountain ecosystem will react to these changes is hard to predict. Adding to the first steps towards predicting the future reaction of the mountains, that is exactly what our article in PLoS ONE was about (check here the scientific version: Lembrechts, Milbau and Nijs (2014)).

Our main research goal was to study the reaction of the alpine plant world to the building of roads. One lonely road to the top often marks the beginning of an intensive process of disturbance, as it creates access for both tourists and industry. It is well known that roadsides change the ecosystem completely and that they cut the core of the natural vegetation in tiny useless pieces.

Surprisingly, roadsides in the subarctic mountain system allow a HIGHER diversity of plants, as can be seen on this graph. This could sound a bit surprising at first, as we would on first thought expect indeed a negative influence of disturbance.

However, before we all start celebrating this positive outcome, we should have a closer look at the processes that explain this higher species richness. I already highlighted the completely different growing conditions in roadsides. Apparently, these conditions are ideal for a lot of species that normally do not get a chance in the natural system.

In our system, this sudden opportunity for so many species results from the clear negative effect of the roads on the most important plants in the Scandinavian mountains: mosses and crowberries. Together with a limited amount of other berry species, they form an uninterrupted, dense understory. This effectively blocks all germination chances for virtually all other species. The crowberries use an even more vicious trick: they produce chemical compounds that actively limit germination chances of other species. Consequently, the normal, undisturbed ‘climax’ vegetation in the subarctic mountains hosts often not more than a meager ten species, the others are all efficiently outcompeted.

When humans start building roads in these systems, the dense cover of mosses and berries is destroyed. The natural vegetation disappears and the remaining bare soil creates magnificent opportunities for new seedlings of so many species that would otherwise stand no chance at all.

So, the loss of the insuperable bully leaves the playground free for all other plants to flourish. This gives a higher diversity, although it is completely different vegetation than we would expect to find.

But there will be more. It is not only the basic species richness that changes in the roadsides, but the disturbance causes a whole sequence of other effects. More about them in a following post.