Throwback december bis

Worth your visit: our new picture gallery on the right of this blog, Sweden and Norway 2017!

Garden angelica flanking mountain road

Angelica archangelica along mountain road in the northern Scandes, Norway

Another post featuring some of the best pictures from this summers’ field trip, this time from the Norwegian side.

Overlooking the Skjomen valley

With steep mountains, stunning fjords and breath-taking views, the area of northern Norway around Narvik is a fantastic travel destination.

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Summer in the Skjomen valley, northern Norway

Just imagine it being the backdrop of your office…

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More pictures in the picture gallery on the right of this blog.

Overlooking the Skjomen fjord

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Throwback December

Visit the new picture gallery on the right of this blog: Sweden and Norway 2017!

 

Northern wheatear

Oenanthe oenanthe (wheatear), owning the alpine tundra Abisko, Sweden

It’s never too late to remember the summer. With snow currently probably packed high on the Scandinavian mountain tops, and the sun again hidden beneath the horizon for the next few months, it is the perfect moment to look back at those glorious days of the midnight sun.

Husky sledgehounds Lapland

Husky overlooking lake Torneträsk – Laktatjakka valley

In this post, I’ll let you marvel at some amazing sights from Swedish Lapland, but I also  created a little picture gallery on the right of this blog, showcasing the best pictures of our 2017 field season in Scandinavian Lapland. Admire the views and take in the stunning backdrop of mountains that every year temporarily becomes our office, while we all count down the days till a new Arctic midsummer.

Blue heath

Phyllodoce caerulea, blue heath

Reindeer herd on snow patch, Abisko, Lapland

Reindeer herd on a snowpatch

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The final countdown

Quietly and virtually unnoticed, this PhD entered its last year. For over 4 years (5 if you include my master thesis project), I have been working on the story of moving plants. Those readers following the blog from the start, in October 2013 (hello, you, thanks for sticking around!) have seen this story evolve with me, from my first thoughts on that very first experiment (what drives plant invasion in mountains?), to a broad topic with branches expanding in all directions.

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Now, with the last year truly started, we are more than ever aiming for the future. I have to finish my doctoral thesis, of course, but mostly we will be developing new projects, applying for money, establishing new collaborations; getting new plans on the rails.

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The road is never easy, but luckily roadmarks and trustworthy guides are never far away

So these are critical times. My little PhD-raft has clearly been caught onto a series of rapids on the river of science. Yet a raft built on great ideas, tied together with a network of fantastic colleagues, is not likely to sink, no matter how wild the rapids are. I can confirm I am still in control of the rudder of my raft, and enjoying the ride. And more than ever curious and excited about what is hiding downstreams.

The harbour in the village of Torneträsk

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Autumn

 

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Autumn colours on the university campus

In autumn, leaves rapidly loose photosynthetic efficiency when chlorophyll is broken down, which reflects in their levels of chlorophyll fluorescence. This breaking down of chlorophyll is a patchy process, however, with increasing variation in fluorescence levels when leaves start coloring.

It might not be cutting-edge science, yet for the students in our Plant Ecology course it greatly exemplifies to the ease of fluorescence measures, regardless of how complicated and fundamental the theory might be.

As you see, it is that season again, another generation of students initiate into the wonderfull world of plant stress measurements!

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An easy solution to a complicated issue

Biodiversity is important. That is a fact, and it would take a fool to deny it. Yet how important is it exactly? How much does it matter how many species an ecosystem has, or which? Ecologists have been searching for answers to these questions for decades now.

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The role of biodiversity – here a highly diverse tropical rainforest in St. Kitts – on the functioning of ecosystems has been the subject of study for decades.

A common approach to search for the role of biodiversity is through experiments with a very simple set-up: make artificial little ‘ecosystems’ with a varying amount of species in it (from 1 to 20 plant species, for example), give them the same treatment, and measure the effect of this varying species richness on the functioning of the ecosystem (through the production of biomass, for example).

Such experiments undeniably revealed that species richness is crucial, with every added species positively affecting the functioning of the ecosystem (albeit less and less significantly so with every extra species added).

 

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Fig. 1: simplified curve of an ecosystem function (i. e. biomass production) as a function of species richness, showing the positive, yet saturating, effect of increasing species richness in an ecosystem.

Yet there is more to biodiversity than species richness alone. What if you have 20 species in your ecosystem, yet one of them takes up 99 percent of the space, leaving only a tiny bit of space for the 19 others? While theoretically a very rich ecosystem, it does not feel like these 19 species can have much of an effect on ecosystem functioning, does it? It doesn’t. The level of dominance of one or a few species in an otherwise species rich ecosystem is expressed as ‘evenness’. A system with all species equally represented is  called ‘even’; a system with one or a few dominant species is named ‘uneven’.

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Alpine tundra (here in northern Norway) is often highly uneven, as it is dominated by a few dwarf shrub species.

Now you could use the same type of experiments as before to try to unravel the role of this evenness on the functioning of the ecosystem. Unfortunately, this extra dimension makes the amount of combinations  virtually infinite. You would have to vary the relative dominance of several species at several different levels of species richness, and that requires a ton of artificial little ecosystems. For that reason, such experiments are much less frequently executed, and the exact role of evenness in ecosystem functioning had still to be proven conclusively.

And that is exactly where we step in. With our group, we came up with an easy solution for this complicated problem. In our latest paper in the journal Oikos, we show that there is no need for all these demanding experiments varying species evenness. The effects of evenness on ecosystem functioning can easily be derived from the existing richness experiments. It requires only a little trick, as the results of the latter are actually hiding the effects of evenness within them.

This little trick is nothing more than the realisation that a highly uneven ecosystem with one species being dominant, and all others having only one individual, is virtually the same as an ecosystem in which that dominant species is the only one present. Present or not, these individuals of the rare species on average only have the fraction of an impact on ecosystem functions like biomass production.

The great thing is: we already know the ecosystem functioning of the ecosystem with only one species (a monoculture) from the richness experiments, and this can thus simply be transformed to an estimated effect of high unevenness on ecosystem functioning.

Applying this little trick to real experimental data worked great. It also revealed that the effects of species richness and evenness on ecosystem functioning point in the same direction (and are both positive). Moreover, we can now see for all ecosystem functions that the positive effect of evenness increases with increasing richness of the ecosystem, without the need for resource-intensive experiments.

Simple as that.

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A true loss of species and a loss of evenness within your species community both have similar negative effects on the functioning of your ecosystem. Picture showing rainforest in Martinique.

To get all the details on our trick, check out the paper!

Lembrechts JJ, De Boeck H, Liao J, Milbau A, Nijs I (2017). Effects of species evenness can be derived from species richness – ecosystem functioning relationships. Oikos. 10.1111/oik.04786.

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We’re back!

It has been quiet here on the blog for a while, but now we are finally back, with tons of new stories to share!

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Lush rainforest in Martinique

We took a little break from it all, to the Caribbean, before diving back in head first into the fascinating world of mountain ecology.

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Beach-beauty in Barbados

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Anole lizard in a botanical garden in Martinique

So I hope these pictures from paradise convince you there were good reasons to stay off the radar for a bit, while hot beaches and tropical rainforest provided a welcome contrast to the – never dissapointing, though – cold roughness of the mountains. The last month however saw a lot more going on behind the scenes than only relaxing. We have been frantically setting up some new projects and consolidating some fascinating new plans, which we will share with you soon!

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Water-taxi in Haiti

So, welcome back, enjoy all the new stuff we will be bringing you shortly, and join us into the final year of the amazing journey that has been this PhD. But more on that later…

 

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Iguana in the city-center of Fort-de-France, Martinique

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Rainforest view with tower of old rum distillary (bottom left), St. Kitts

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A visit to the south

The faculty of agro-science in Gembloux

Today, we spent the day in Gembloux, in the southern part of Belgium. A cosy little city with a beautiful university.

While the always-welcoming feel of the south made it feel like a holiday, it was far from that: we’re finally starting our joint project on plant invasion in Belgian cities, and it promises to be awesome!

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