image: Summer 2002 flood of the Middle Elbe (Germany). view more
Credit: André Künzelmann/UFZ
This release is available in German.
Dessau. Extreme flood events in floodplain grasslands affect carabid beetles and molluscs more than plants. This is the finding of a study by biologists from the Helmholtz Centre for Environmental Research (UFZ), TU Berlin, the German Federal Institute of Hydrology (BfG), ÖKON Kallmünz and the ILN Bühl, following several years of observations before and after the Elbe floods of August 2002. Flow variations are known to be most important drivers in structuring riverine communities. However, until now, the effects of extreme flood events on the flora and fauna of floodplains have been largely unknown, despite the fact that such events are likely to become more frequent as a result of climate change, say the researchers, writing in the latest issue of the journal "Ecology". They surveyed plants, carabid beetles and molluscs in spring and autumn at 36 plots on an Elbe floodplain grassland that was flooded in 2002. Data from 1998 and 1999 were compared with data from 2003 and 2004.
The samples were taken from marked plots in riverine grassland near Dessau (UNESCO-Biosphere Reserve Riverine Landscape Elbe - Saxony-Anhalt) measuring almost one square kilometre which is flooded seasonally by the Elbe. During the 2002 flood these plots were submerged for at least two weeks, with the water height ranging from 2.4 to 5.4 metres above soil level.
"Our findings show that the mollusc and carabid beetle communities were the most severely affected by the floods," explains Christiane Ilg of the UFZ. "This disproves the hypothesis that groups with lower mobility are more severely affected by floods being less able to escape, and that they recolonise the flooded habitat only after some delay." The number of carabid beetles fell from 117 species before the flood to 88 immediately after the flood, but had recovered by 2004, quickly returning to their pre-flood level. Surprisingly, populations that are adapted to moist conditions and partly are good swimmers were the most severely affected and lost over 40 per cent of their species richness. Carabid beetles may have adapted well to floods over the course of their evolution, but these adaptations aim the survival through the typical winter and spring floods. This is why a summertime flood can have such a drastic effect on the number of carabid beetles. Because of their high mobility, however, these species also recovered the fastest. Land snails were not seriously affected by the 2002 summer flood, their abundance and species richness remaining similar to the ones observed in the pre-flood years. Merely, water mollusc species and individuals increased following the flood.
The vegetation was the least affected by the flood. The decline from 113 plant species to 107 is of hardly any significance in statistical terms. However, further analyses show that the frequency of several species drastically decreased whereas other species, on the contrary, benefited from the flood. The vegetation evidently is well adapted to flooding.
Although this research is the first to provide data about the impacts of such extreme events on flora and fauna, the researchers stress that it is difficult to infer long-term consequences from one flood: "We believe that long-term monitoring of floodplain ecosystems with standardised methods is essential to assess the consequences of an increased frequency of extreme events on floodplain biodiversity."
Publication:
Christiane Ilg, Frank Dziock, Francis Foeckler, Klaus Follner, Michael Gerisch, Judith Glaeser, Anke Rink, Arno Schanowski, Mathias Scholz, Oskar Deichner, and Klaus Henle: LONG-TERM REACTIONS OF PLANTS AND MACROINVERTEBRATES TO EXTREME FLOODS IN FLOODPLAIN GRASSLANDS. Ecology: Vol. 89, No. 9, pp. 2392-2398. DOI: 10.1890/08-0528.1
http://www.esajournals.org/perlserv/?request=get-abstract&doi=10.1890%2F08-0528.1
The research was funded by the German Federal Ministry of Education and Research (BMBF) and the German Federal Institute of Hydrology (BfG) with support from the Middle Elbe Biosphere Reserve.
More specialist information available from:
Dr Christiane Ilg, Mathias Scholz, Dr Judith Glaeser, Michael Gerisch
Helmholtz Centre for Environmental Research (UFZ)
Telephone: +49 (0)341 235 1643/1644
http://www.ufz.de/index.php?en=10468
http://www.ufz.de/index.php?de=1933
http://www.ufz.de/index.php?en=2163
http://www.ufz.de/index.php?en=15479
Prof. Dr. Frank Dziock
Technische Universität Berlin
Telephone: +49 (0)30 314 71368/71350
http://www.biodiv.tu-berlin.de/
Dr. Francis Foeckler
ÖKON GmbH
Telefon: 09473-951740
http://www.biodiv.de/index.php?L=0&id=63
http://www.oekon.com/
Tilo Arnhold (UFZ press office)
Telephone: +49 (0)341 235 1269
Email: presse@ufz.de
Related links:
HABEX – Floodplain habitats after extreme flood events; impacts of the Elbe flood 2002 on flora and fauna: http://www.ufz.de/index.php?en=5542
Middle Elbe Biosphere Reserve: http://www.elbebiber.de/contenido_468/cms/front_content.php?idcat=1&changelang=3
More on the topic of biodiversity can be found in a special issue of the UFZ newsletter marking the 9th meeting of the Conference of the Parties to the Convention on Biological Diversity (COP9), which was held in Bonn in May 2008: http://www.ufz.de/index.php?en=16853
At the Helmholtz Centre for Environmental Research (UFZ) scientists research the causes and consequences of far-reaching environmental changes. They study water resources, biological diversity, the consequences of climate change and adaptation possibilities, environmental and biotechnologies, bio energy, the behaviour of chemicals in the environment and their effect on health, as well as modelling and social science issues. Their guiding research principle is supporting the sustainable use of natural resources and helping to secure these basic requirements of life over the long term under the influence of global change. The UFZ employs 900 people at its sites in Leipzig, Halle and Magdeburg. It is funded by the German government and by the states of Saxony and Saxony-Anhalt.
The Helmholtz Association helps solve major, pressing challenges facing society, science and the economy with top scientific achievements in six research areas: Energy, Earth and Environment, Health, Key Technologies, Structure of Matter, Transport and Space. With 25,700 employees in 15 research centres and an annual budget of around EUR 2.3 billion, the Helmholtz Association is Germany's largest scientific organisation. Its work follows in the tradition of the great natural scientist Hermann von Helmholtz (1821-1894).
Journal
Ecology