The science

My research tells the fascinating story about plants’ struggle to survive the harsh circumstances in the outside world… It is my goal to unravel the secrets and mysteries of what happens in the world of plants, and ultimately use my knowledge to save their beauty.

On this page, I want to give a brief overview of where my research is heading. For a short scientific overview of my projects and publications, please refer to my PhD-cv

Kärkevagge

Plants are dealing with a constant struggle to survive in the harsh outside world. Even in the worst of circumstances, like those on the tops of mountains, the dreadful droughts of a hot summer or the extreme wetness of a winter flood, plants manage to survive. And they even have to cope with more than only those harsh climates, they are also always in a constant struggling competition with their neighboring plants.

Brave little birch

Surviving at its finest

The aim of my research is to find the main restrictive factors in the environment, on a time– and spatial scale relevant to the plants, and both above- and below ground. These restrictive factors will then shed light – even more important – on the ability of plants to overcome these difficulties and survive, against all odds.

To study the struggle against the extremes, we can find an interesting natural experiment in mountains, where human disturbance changes conditions and interactions. This disturbance, starting from the lowlands and slowly crawling to higher elevations, starts a cascade of effects, both positive and negative, that will ultimately define if we will be able to keep our mountain nature as it is. Disturbance is one of the main topics of my PhD, and discussed in detail here.

Summer snowThe best example of changing conditions caused by human disturbance is provided by roads. Concerning their effect on the native plant communities, we observe a higher species richness in roadsides, which turns out to be mainly due to an input of competitive weeds in the lowlands, but might as well be linked to both an upward ànd downward shift in species.

Snow

On high elevations, we find another kind of species in the roadsides. There they have to cope with the very harsh climate that is typical for mountains. Only the tough ones, with millions of years of evolutionary adaptation, manage to survive. They are  armed with adaptations to  short growing seasons,  frost,  snow, strong winds, stony soils, lack of nutrients and excessive radiation.

For lowland plants, this world is a true nightmare. They don’t have all these nice adaptations, like small leaves, huge root systems, water holding qualities, anti freezing solutions,… They have broad, vulnerable leaves, created to grow quickly when resources are available.

Dandelion3However, this clear distinction between low- and highlands gets bridged by so-called aliens (?), plants that do not belong up there, but that are transported to higher elevations by humans. They make use of roads to get to higher elevations, clinging to soles of shoes and tires of cars. Nowadays, large groups of them are marching uphill, possibly becoming invasive species: aliens that start spreading fast and sometimes even grow as tall or taller than in their home range. More on alien species, another main subject of this PhD, in general and why their study is important: here.

We will unravel why and how these non-native species can survive in unexpected stressful (too hot, too wet, too poor, too dry…) environments. Our main targets: disturbance, nutrient addition and microclimate.

Trifolium repens

Projects

I am currently working on several projects (all details here) concerning both plant invasions, mountain vegetation and their interaction. How this really works on a day-to-day base can be read in the PhD-path.

In a first project, that started in the summer of 2012, we recorded native and alien species composition along roadsides and in the natural vegetation in mountains in northern Scandinavia. This project forms part of a global network studying mountain roads, called MIREN. In this local survey, we noticed large changes in native vegetation caused by the disturbing effects of the roads, but also a totally different behavior of the alpine compared to the lowland vegetation. Alien species showed a strong connection with roadsides, but we realized their was a bigger danger for invasion in the natural vegetation on high elevations. Future plans are to link the patterns of both native and invasive plant species to changes in microclimate, predict future effects of climate and land-use change and include countless other processes in the equation, like the interaction with soil fungi (mycorrhizae).

PlotIn a second project, started in the summer of 2014 for a period of 2 years, we try to unravel the factors limiting or promoting plant invasions in mountains. We aim to predict the amount of danger for the future. Herefore, we installed field sites in Sweden and Chile, where we planted seeds on different elevations in the mountains. I went back several times to measure germination rates of our plants.

Huge invasive red clover

The fieldwork of this experiment is finished, both in Sweden and Chile, and the results look impressive, as many of the non-native species managed to grow in unexpected circumstances well beyond their predicted limits. The results were published in PNAS, where we show that disturbance is indeed the main driver of plant invasions in these cold environments, yet that chances are high that invasions will rapidly increase in the near future.

A third project that started in Belgium, focusses on variation on the smallest scale in temperature and other abiotic conditions and how species can manage to grow outside their predicted range if the micro scale gives the exact best combination of possibilities. I will show how disturbances of different sizes will change abiotic conditions and consequently competition and facilitation. I try to unravel how plants will ultimately choose the best combination of both, depending on the season. Zooming in on the disturbance, yet also on the plants themselves: do they show different behaviour throughout their lives? Which circumstances are necessary for the ultimate success; being able to produce offspring?

A fourth project consists of a global modelling exercise to keep track of the movements of plants in the mountains. We aim to make these prediction models better by including microclimate (the climate on the (centi)meter-scale that plants truly experience).

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