22.01.2015 11:57 Age: 3 yrs

Study investigates impact of catastrophic 2013 flooding: Fields with high diversity benefit from being submerged

Extreme weather events are becoming more frequent because of climate change. European countries will have to expect further catastrophic flooding on a similar scale to June 2013. Now a research team involving scientists from TUM has discovered that grassland with high diversity actually benefits from inundation. When a high number of species are present, grassland becomes more effective at converting the influx of resources from the flood water into biomass. The study was published in Nature Communications.

The 2013 floods showed scientists working on the Jena Experiment that biodiverse grassland can benefit from being submerged. (Photo: Victor Malakhov / iDiv)

In early June 2013, central Europe was hit by massive flooding which caused well over EUR 12 billion worth of damage. In Germany, several rivers broke their banks, including the Saale in Thuringia. This caused the inundation of the Jena Experiment in biodiversity, where researchers have been studying the effects of species extinction in hay meadows since 2002. 

A team under Nico Eisenhauer, Professor at the German Centre for Integrative Biodiversity Research (iDiv) and the University of Leipzig who headed up the study, investigated the impact of the flooding. They took this opportunity to test some of the hypotheses put forward by scientists and ecologists over the past 30 years, but which up to now have never been verified in the context of massive flood events. 

The researchers discovered that “biodiverse plant communities are able to use additional water and nutrients more efficiently than communities with fewer species. They were able to demonstrate for the first time a scenario in which plots with greater biodiversity produced more biomass, but were also less stable,” explains Dr. Alexandra Wright, adding that: “These results show that biodiverse plant communities react in very different ways to extreme environmental events and that stability should not necessarily be the prime consideration when assessing how an ecosystem functions.” 

The assumption up to now has been that individual species in biodiverse communities are more likely to tolerate disturbance and thus withstand the impact of this disturbance. The study shows that the opposite is true: biodiverse plant communities are more “unstable” – that is, their rate of biomass production deviated the most compared to previous years. 

“The flooding event which hit the Jena Experiment in June 2013 was a complete surprise – some areas were completely submerged for up to three weeks,” comments Prof. Eisenhauer. “We were worried that the experiment could be ruined because of this major disruption,” adds Prof. Wolfgang Weißer from TUM, spokesperson for the Jena Experiment.

However, the scientists managed to turn the situation to their advantage and set about studying the impact of the flooding in detail. Dr. Anne Ebeling, Scientific Coordinator at the University of Jena, explains: “Within a very short space of time we were able to organize a number of additional measurements. This was made possible by the wide-ranging expertise available to the Jena Experiment, where plant ecologists, soil ecologists, hydrologists, chemists and zoologists are working side by side.” 

The study brings together scientists from iDiv, the University of Leipzig, Friedrich Schiller University Jena and TUM.

The Jena Experiment is one of the longest-running biodiversity studies in Europe. Its aim is to understand the relationships between plant diversity and ecosystem processes in grassland. Scientists are studying 80 experimental fields each with an area of 30 m2 and noting how their biodiversity is impacted by processes which take place above and below the ground.


Publication:
Flooding disturbances increase resource availability and productivity, but reduce stability in diverse plant communities; Alexandra J. Wright, Anne Ebeling, Hans de Kroon, Christiane Roscher, Alexandra Weigelt, Nina Buchmann, Tina Buchmann, Christine Fischer, Nina Hacker, Anke Hildebrandt, Sophia Leimer, Liesje Mommer, Yvonne Oelmann, Stefan Scheu, Katja Steinauer, Tanja Strecker, Wolfgang Weisser, Wolfgang Wilcke & Nico Eisenhauer, Nature Communications; DOI: 10.1038/ncomms7092

Contact:
Prof. Dr. Wolfgang Weißer
Technische Universität München
Chair of Terrestrial Ecology
Phone: +49 8161 71-3496
wolfgang.weisser[at]tum.de
www.toek.wzw.tum.de

Prof. Dr. Nico Eisenhauer
German Centre for Integrative Biodiversity Research (iDiv) Halle­Jena­Leipzig
Phone: +49 341 97-33167
nico.eisenhauer[at]idiv.de
www.idiv-biodiversity.de