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Biodiversity, an elixir?

The positive effects of biodiversity in plant communities have been established over the last few decades. Interaction networks among species are tuned so as to be less negative and more positive over time making plant communities more productive and stable. The question we wanted to answer was do evolutionary processes in plant communities lead to measurable evolutionary changes in plants in single species and mixed species communities.

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The paper in Nature Ecology & Evolution is here: go.nature.com/2mWFPVD

Scientists are often perceived as existing in an ivory tower, for scientists in the field of ecology this is very often far from the truth. Our experiments and data collection often mean we spend long days in exposed grasslands, hiking through sweltering tropical forests, or in the thin air and low temperatures of high altitudes to reach our research sites. But it is being out in the field that gives us the core ideas for our work.

Our experiment stemmed from ongoing debates surrounding the role of biodiversity in regulating ecosystem function, but more directly from a long running grassland field experiment in Jena, Germany. The Jena Experiment provided an ideal opportunity to collect plants to test mechanisms concerning the long-term (i.e. evolutionary) influence of plant species diversity on biodiversity effects. Whilst being an excellent experimental platform for plant ecology, the Jena site however is not always kind to ecologists who have to spend many hours in the open in all weather conditions.

Image 1: The Jena Experiment from where we collected the plants for our experiment. Scientists and technical assistants at work, collecting the plant material at the field site in Jena. The hat was not for protection against the sun but for warmth! © Matthias Furler

Over a couple of cold, mostly clear days in the spring of 2010 we collected the plants for our experiment, working very long chilly hours to make sure the plants were collected within a suitable time frame.

Image 2: Even scientists and their assistants need to rest sometimes! © Matthias Furler

Once we had collected over 4000 plants, we needed to transport them quickly to Zurich in Switzerland, all the while making sure the roots were kept moist to reduce transplant shock from being driven almost 600 km and replanted into their new plots.  

Image 3: Ecological experiments are always a result of team work from conception to completion. © Matthias Furler, © Debra Zuppinger-Dingley

The cold, very wet weather during replanting was exceptionally good for the plants, for us not so much. We were really lucky however to have the perfect weather for each stage of this process concluding with a warm summer ensuring we could collect sufficient seeds for our experiments.

Image 4: The propagation plots well established in Zurich and netted to reduce cross-pollination of plants from different diversity levels. © Debra Zuppinger-Dingley

All that was left to do were the many hours cleaning the seeds by hand to get them ready for sowing and then to set up the experiment.

Anybody who works with plants will tell you it is quite a nerve-racking experience, involving much patience and strong nerves. We sowed many seeds, more than we needed as germination is not always certain.  After some nail-biting days the news was good, germination was a success. We had all the plant material to set up the experiment we needed to answer our question.

Image 5: Hand cleaning the precious seeds to make sure we did not lose many seeds. Checking on a new batch of cuttings for block 1 of the experiment in the experimental greenhouse. Success, the seedlings for block 2 growing well! Looking after the experiment was not easy during hay fever season. © Debra Zuppinger-Dingley, © Leigh Oesch, © Daniel Zuppinger

Our results showing that only diverse plant communities lead to the evolution of more positive interactions, thereby increasing the positive effects of ecosystem functioning, has surprised many scientists in this field, and has emphasized the need to focus on evolutionary processes as well as ecological processes in biodiversity research.

Acknowledgements

Thank you to all at the Jena Experiment which is funded by the Deutsche Forschungsgemeinschaft (DFG). We would like to give special thanks to Bernhard Schmid. Thanks too to Daniel Trujillo Villegas, Leigh Oesch, Theres Zwimpfer, Matthias Furler, René Husi for their practical assistance and the people of the Jena Experiment. For financial support, thanks to the University Research Priority Program on Global Change and Biodiversity of the University of Zurich, Swiss National Science Foundation and the Rural & Environment Science & Analytical Services Division of the Scottish Government through the Strategic Research Programme.

Go to the profile of Debra Zuppinger-Dingley

Debra Zuppinger-Dingley

Research Associate, University of Zurich

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