Road effects

5 years later, we are getting ready for a re-survey of our longterm observational plots along the roads in the Norwegian mountains. The perfect moment to summarize for a second what we learned from our first trip.

Roadsides host more plant species than the natural vegetation. That is the conclusion I drew 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, versus the black line and dots representing the roadside) in the natural vegetation.

Graph native species richness

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 mentioned in the previous post), is less intense here. More open spots, less competition, more diverse habitats, all kinds of factors that could explain the higher plant diversity as revealed by the graph. All of this explains the higher species richness on high elevations. But why don’t we have the additional higher species richness in roadsides here as well, as we saw in the lowland roadsides?

Alpine vegetation

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, Epilobium angustifolium, see picture). They do not belong in such numbers in the ‘traditional’ undisturbed subarctic mountain vegetation, but typically follow humans, agriculture and the availability of rich soils and mild conditions. Such culture followers form 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.

Hairy willowweed, a typical competitive weed

These competitive weeds are rare in the roadsides on high elevations, where conditions are a lot harsher. The roadsides there serve more as a refuge for stress-tolerant alpine species, because the difference in environmental conditions with the surrounding undisturbed areas is much smaller: both contain open, low vegetation, with a lot of bare rock, exposed to the harsh climate. Ideal circumstances for stress-tolerant plants (like Saxifraga stellaris, see picture), yet a disaster for the competitive kind.

Saxifraga, a typical stress-tolerant alpine species

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.

Roadside vegetation

You want to know the exact scientific story? Here it is!

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What is hiding in mountain roadsides?

5 years later, we are getting ready for a re-survey of our longterm observational plots along the roads in the Norwegian mountains. The perfect moment to summarize for a second what we learned from our first trip.

View on the valley of the Abiskojokka
Autumn in the Arctic mountains, the setting for our research. All pictures from the previous campaign in 2012.

Mountains are increasingly important islands of pristine 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 is important even from an economic viewpoint.


For now, alpine ecosystems are among the least disturbed ecosystems in the world. However, climate change and increasing levels of human influence are rapidly changing the face of our mountain nature. A clear example of this human influence is given by the building of roads in mountains, which does not only physically disturb the alpine vegetation, yet also initiates an avalanche of consecutive effects on the mountain ecosystem.

View on Abisko village

With our long-term observational project, we study the reaction of the alpine vegetation to such mountain 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 in all its facets and that they cut the core of undisturbed vegetation in smaller, devaluated pieces.


Perhaps surprisingly, roadsides in the subarctic mountain system host a HIGHER plant diversity, as can be seen on the following graph. A counter-intuitive result, at first sight, as you might not have expected any positive effect of such a radical disturbance on nature.

 Graph native richness

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 plant species in the Scandinavian mountains: mosses and crowberries. Together with a few other berry species, they create an  uninterrupted, dense understory. This dense mattress 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 their competitors for space. Consequently, the normal, undisturbed ‘climax’ vegetation in the subarctic mountains often hosts only a meager ten species, the others are all efficiently outcompeted.

Crowberry - Empetrum nigrum


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.

Road in the autumn

So, the loss of the insuperable bully leaves the playground free for all other plants to flourish. This gives a higher diversity, although the resulting vegetation is completely different from the one occurring naturally in the mountains.

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 those in a next post.

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5 years later

Summer 2012. I was a young masters student, spending my first month of many above the polar circle. I joined a global consortium called MIREN, the Mountain Invasion Research Network, that surveyed plant invasions along roads in mountain regions scattered across the globe.

Eriophorum vaginatum – pictures from our 2012 campaign

With 3 roads in the north of Norway, close to Narvik, we added the northernmost sample sites to this expanding network. With its short summers, freezing winters, yet surprisingly versatile plant species, the Northern Scandes promised to be very interesting.

One of our Norwegian roads in early summer

The unfortunately cold Nordic summer of 2012 was spent surveying these roads, monitoring all plant species that grew in the roadside or the adjacent natural vegetation, with the aim to initiate a long-term monitoring project of the movement of the plant species.

The study area in northern Norway

We are now in the year 2017, five years after this memorable first survey. Time to bring a new team together, with one ambitious goal: return to exactly the same plots that were first surveyed in the summer of 2012, and investigate in detail what happens to the species on the move. A challenge made possible thanks to the INTERACT Transnational Access program.

Midnight sun above lake Torneträsk, Sweden

In a series of posts, we will first cover what came out of the first survey, followed by the fieldwork adventures we encounter on our new mission. Stay tuned, because this will be our most exciting summer of the century (or, well, at least the last 5 years of it…).


More on this and many other topics covered in my PhD on my personal website.

The Anti-Arctic

When the arctic is covered in snow, we turn our scientific interests to the other side of the world: the (sub)antarctic. Our goal is to see if the patterns in the vegetation we observe at one part of the globe – the subarctic world of Lapland – hold true at the completely opposite side as well.

Local Nothofagus forest in the snow
Subantarctic Nothofagus forest in the snow

With this idea in mind, we go to the city of Punta Arenas, on the absolute southernmost point of the American continent. There we study the possibilities of exotic plant invasion in extreme environments. With these trips to the south we hope to come up with a comparison of the limits for common Western European weeds on this far away location with what we know and learn in Northern Scandinavia.

Flowers of invading red clover in South America
Flowers of invading red clover in South America

Our last field trip has been in April, when summer on the southern hemisphere disappeared and made way for snowy autumn storms. This intermediate season presented us with true roller-coaster weather, with freezing lows and icy storms right before the clearest blue skies.

Our high elevation plots covered in unexpected early autumn snow
Our high elevation plots covered in unexpected early autumn snow

The results of this last trip to the south look very promising at first sight. The climatic gradient in the mountains around the city of Punta Arenas turns out to be a pretty drastic one. In the city itself, the ocean buffers temperatures and weather is cold but mild, in fact more a borderline temperate climate than a true subantarctic one.

Huge invasive red clover after harvest
Huge invasive red clover after harvest

The nonnative European species, like the well-known dandelion and white and red clover, profit from these mild circumstances and flourish sometimes even more than in their native range!

Large clover leave
Large clover leave

Several hundred meters above the city, however, you arrive in a different place. The howling winds that already torture the city of Punta Arenas all year round, can blow even more freely up here, and temperatures drop to zero almost every night during the whole summer season. This environment feels much more like Antarctica, the icy continent that is so close-by.

Antarctic feel on top of the mountain
Antarctic feel on top of the mountain

Plants see their growing season reduced to less than half of the months they have at sea level. The negative effects on plant performance are inevitable. Where the nonnative species seemed to be unimpressed by the climate within the safe boundaries of the city, their survival and growth is reduced to virtually zero on the highest elevations.

A little mouse that did not seem to mind the extreme circumstances
A little mouse that does not seem to mind the extreme climatic circumstances on top of the mountains

Interestingly, the interactions of our invaders with the established vegetation seem to change as fast as the weather. However, we have to dig in the data first to get those patterns clear. Hopefully soon more news about that!


And afterwards, it is back to the Arctic, where summer is finally on its way again!

Click here for more information about my research on top of the world.

Flying a helicopter

This post was originally posted on ‘On top of the world‘.

Our most remote plots involve hours of climbing on steep mountain slopes, through dense willow shrubs and over dry rocky areas.


But not this time. This time we had to walk for 20 minutes to Abisko’s helicopter base and do the full hourlong walk in less than 5 minutes.


The helicopter was a nice, big red insect that we had seen zooming around through the mountains before. But now, it was us who had to put our luggage in its trunk, put on the huge headset and communicate like true professionals through the microphone.


The flight itself was as exciting as it was short. The helicopter was really stable, so you almost could not feel the lift-off. It sheered closely over the mountains, right past the famous Lapporten gate, and in no-time we reached the top.


There, the helicopter quickly dropped us off – landing on the open Arctic tundra was no problem – and we ran away of its swirling propellers.


We were up on the mountain top at 8:50 in the morning, the earliest we have ever been. Of course, the rest of the day, working and walking downhill, were as easy as can be, so we managed to do a lot more than expected.


If it was not for the money, I would not mind more of this way of travelling in the future!  DSC_0031

Please do not disturb

On top of the world

If you leave your experiment behind in the Scandinavian mountains, you will have to deal with the wildlife up there.

Reindeer and Lapporten

We learned that lesson the hard way. It turns out that the high north houses a high density of reindeer, a fact we immediately noticed in our plots: labels destroyed, large footprints everywhere, flowers eaten, even some dung piles… The reindeer seemed to be attracted to our research!

Sassy rein

The first few days, we only saw their tracks, obvious as they were. It only took us some time to finally see one in real life.

Reindeer and Torneträsk

We thought they might have been hiding from us far away in the mountains, on the highest and less-visited peaks, but in the end our first sighting was right next to the chairlift, on the most touristical location in the whole northern mountain range.

Reindeer and chairlift

The next day, we saw some more disturbers, with impressive antlers and a fierce look.

Majestic reindeer bull

They were too majestic…

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A happy reunion

This July, we planted seeds on 1000 meters in the mountains, well above their current growing limits.

Scinece on top of the world

Now, at the end of August, we were very curious to see if they managed to germinate. It was an exciting hike to the top, our thoughts switching between ‘oh no,everything will be dead!’ and ‘this gonna be so good!’

Enjoying the view

Luckily the worries did not distract us too much from our environment, so we did not miss the amazing waterfall on our way to the top.

On top of a waterfall

In the end, everything turned out perfect. The plants did as we expected, with some strong individuals even growing amazingly swift for these high elevations. It was a happy reunion with the plots we left behind in the beginning of the summer. Soon we had to leave them again however, and now for the cold and dark winter nights. Growing plants

Our nice preparation at home ànd our good fieldwork in July made sure all our work now went as smoothly as could be. Good news, because it gave us time to hike up to the top of the mountain, were rumours said delicious waffles were served.

Laktajakka waffle place

It took us a little bit more time than expected to hike to the top, but the waffle house was found, at the end of a beautiful walk through a wild landscape.

Explosion in the lake

The waffles were well earned, and tasted even better after the long climb and the succesfull fieldwork of the day. DSC_0170More on our research here!


Back to the top

We are back in Abisko after two months. Right before the start of the rainy autumn weather – it might fall upon us on our last day – we are here to harvest the seedlings of our two-year experiment.


We take a week to skim the mountains and bring down the harvest to the research station.


Our nonnative species now had two growing seasons to show their best survival skills. For most of them, that turned out to be barely a centimeter of growth, but there were also some heros that made into full grown plants.


The hikes in the mountains gave us the opportunity to enjoy the beautiful end-of-august atmosphere in the Swedish mountains. Beautiful colours in the sun, amazing little fuzzy plants, pretty golden mushrooms and cute lemmings collecting their winter fat.

Fuzzy plants


Fuzzy plants

The sun is still around for some days, so we gonna make the most out of our short stay in the north. We might take some seconds to harvest two or three blueberries, we might take a detour to get a nice view on the valley, but we will especially enjoy the nice data we are collecting, as they promise us so many fascinating answers.

High elevation plots

More pictures of our field trips to Sweden here!

Autumn in the mountains

Mushroom    Fuzzy seeds of dryas octopetala      Asteraceae

Fjord and fjäll

We ended our Scandinavian fieldwork trip with two days at the other sides of the mountains. We had to find back the Norwegian plots of the roadside research of two years ago to install temperature sensors in the soil.

Alien species along the fjord

This little trip brought us the highlights of the Norwegian summer in a peaceful valley called Sjkomdal, in this season a true example of a Scandinavian paradise.

Picturesque valley of Skjomdal

We traveled up and down between the softness of the grasslands in the valley and the breathtaking views from the mountain tops.

Summer in the Skjomdal

Marsh in a valley in Northern Norway

The ultimate goal was to find back the sticks that had been waiting for two years in the immense eternal forests and tundra to mark the location of all plots. For the next year, they will guard the temperature sensors until I come back to pick them up.

Marking of the plots

Luckily, we had gps-coordinates, pictures of the locations and some marks in the field to help us on this true treasure hunt. This facilitated the search drastically, although some sticks still managed to disappear untraceably over the years.

Finding back the marks

It was nice to be reunited with my plots after two years; coming back there felt like revisiting a childhood playground. With the help of two days of fantastic summer weather, I now finally realized the full beauty of the area and the luck we had to do science up there.

Cottongrass overlooking a marsh in a valley

After a long and hot day of climbing the mountains, we set up our tent close to a lovely and cute ‘Fjällbuhytta’, right above a river perfectly suited for an evening swim. We took our time to swim away the dust of the working day and watched the alpenglow on the mountains at midnight.

Little Fjellbuhytte in the middle of a Norwegian forest

Mission accomplished in the best of circumstances, that is one thing that makes ecology so amazing!

Alpine invasions

When plants from the cosy environment of western Europe arrive in the high north, you would expect they are not used to the cold environment over there. Some of them however seem to do pretty well in the Swedish mountains, unlike what could be expected based on the climatic conditions in these harsh environments.

Dryas octopetala in the mountains

We want to know the limitations of these species, explore their powers on these absolute limits and see how high they can get. And even more important: we want to know the factors that might block or promote their expansion. These results will be a great help in the predictions of future changes in plant distributions and the effects on the typical mountain vegetation.

Alpine vegetation in Sweden

So we decided to climb all the way up to 1000 meters in the mountains in the high north (more pictures here) to put our tiny, vulnerable plant seeds in the ground. We could derive their performance up to 900 meters already from last years experiments, but their limitations might even lie higher. So we crossed some large snowfields and hiked our way up to see if the plants would be able to follow.

Climbing the highest mountains

It is important to realize that the elevational limitations of the invaders will strongly depend on location and circumstances. They might be limited to a unique combination of environmental factors, but use those locations to expand their ranges to higher elevations. Even we felt the differences in circumstances over only a hike of a few kilometers: areas with or without wind, patches that accumulate snow or drain all the melting water or cliffs to steep for plants to grow.

Plots at 1000 meters

We make use of this natural variation in the mountains to get a detailed view of the possibilities of the invaders and predict their future.

Plots at 1000 meters

The current sequence of warm days at the beginning of the Arctic summer can be used for the installation of the experiments. At the end of august and after the long and harsh winter, we will come back to count the survivors.

The midnight sun