Scientist

Faculty of Biology
Aquatic Ecology
Universitätsstrasse 5
D-45141 Essen
Germany

Room S05T03B02
Phone: +49.201.18.33113
Fax: +49.201.18.32179

cornelia.wagner@uni-due.de

PhD thesis: Spatial colonization patterns of floodplain biocoenoses as a basis for assessment procedures and renaturation measures

Floodplains are considered hotspots of biodiversity, but are highly impaired by humans. In Germany, they are severely degraded - in particular due to river straightening and the decoupling of floodplains from watercourses. This has led to a considerable loss of habitat diversity and ecological functions and thus also to an extreme loss of biodiversity. Although restoration measures are on the increase - encouraged by political initiatives such as the EU Restoration Regulation - many of the ecological mechanisms that determine the success of such measures are still poorly understood. In particular, there is a lack of large-scale comparative analyses of biodiversity in floodplain landscapes.
This doctoral project investigates spatial patterns of biodiversity in floodplains using standardized data from the “BioAu-Praxistest” project, which is funded by the Federal Agency for Nature Conservation (BfN). The survey was carried out for five groups of organisms - vascular plants, molluscs, ground beetles, amphibians and birds - in five differently degraded floodplain sections on each of five rivers: Danube, Isar, Lippe, Oder and Ruhr.
The project is funded by a doctoral scholarship from the German Federal Environmental Foundation (DBU).
Three questions/topics are being investigated:

1. Colonization patterns in floodplains: How does the biodiversity of different groups of organisms vary at different spatial scales - from individual habitats to entire river systems?
The aim is to find out whether restoration contributes to biodiversity primarily through the creation of new habitats or through the diversification of existing structures.

2. Species vs. functional diversity: Are differences in functional characteristics between degraded and near-natural floodplain sections more pronounced than differences in species composition?
This question serves to clarify whether changes in habitat structure also improve ecological functions.

3. Colonization patterns in alternating wet grassland: In-depth investigation of biodiversity patterns in grassland, which is not further differentiated in previous assessment methods.
New field data planned for 2026 should help to further develop assessment methods - especially for monitoring the success of renaturation measures.

The results of the project should show which habitats and habitat qualities are particularly relevant for species and functional diversity in floodplains - and thus contribute to the development of more effective and ecologically sound restoration strategies.