Which plants grow on the dikes in coastal areas and how these are maintained has an impact on the dikes’ resilience in the face of climate change and extreme weather events. A new study from the Ludwig Franzius Institute of Hydraulic, Estuarine and Coastal Engineering (LuFI) at Leibniz University Hannover has demonstrated this. As part of a field study on Lower Saxony’s North Sea coast (Langwarder Groden, Butjadingen), the researchers planted two different seed mixtures on a section of summer dike selected for this purpose. They then investigated how the emerging plant communities and soil properties were related. They also analysed whether and to what extent increased species diversity can improve the microclimatic stability of dikes during drought periods.
To do this, the researchers compared a plant community dominated by herbs with one dominated by grasses in terms of their impacts on soil temperature and soil moisture. The results showed that the deeper root systems and increased shade provision of the herb-rich vegetation more effectively preserved moisture and mitigated extreme temperature fluctuations during the summer months. This largely prevented the drying out and cracking of the clay cover – a cohesive surface layer of the dike – thus making the coastal protection structures more resistant to the stresses of the subsequent storm-surge season. The study also emphasised that the scheduling of mowing is critical, as the removal of the biomass means the soil is temporarily more susceptible to drying out and temperature fluctuations.
The study’s main author, Jan-Michael Schönebeck, summarises the results as follows: “The findings show that increasing the functional diversity of the grass cover strengthens the dike’s resilience to drought.” The research therefore delivers practical approaches to ecological dike management which bring together natural conservation and flood protection. Prof. Dr.-Ing. Torsten Schlurmann, executive director of LuFI and co-author of the study, adds:“The results of the real-world experiment show the potential of ecosystem-based climate-protection strategies. The composition of the vegetation and dike management can be used in a targeted way to make dikes more resilient to climate change and extreme weather events.”
The findings have been published in the online journal PLOS ONE:
Schoenebeck, J.M., Bunzel, D., Paul, M. and T. Schlurmann. Plant trait diversity buffers soil moisture dynamics on coastal dikes during drought periods. (2026) PLOS ONE, 21 (26 March), art. no. e0345552, https://doi.org/10.1371/journal.pone.0345552
The real-world experiments were carried out as part of the research project “Gute Küste Niedersachsen” (Good Coast – Lower Saxony; project period: 2020–2025), which was funded by the Ministry of Science and Culture of Lower Saxony (MWK) and the Volkswagen Foundation through the zukunft.niedersachsen programme. The project addressed the overarching issue of sustainable, safety-oriented coastal protection. It focused on establishing and proving the effectiveness of nature-based solutions as a synergistic supplement to technical structures on Lower Saxony’s North Sea coast. The transdisciplinary approach ranged from physical modelling and ecological assessment to government-agency and public participation in three real-world labs in Spiekeroog, Neßmersiel and Langwarden. This helped bridge the gap between theoretical research, a needs-based approach and practical application. “The research project was able to confirm that the modern, future-oriented protection of our coasts is a transdisciplinary undertaking that can succeed as an adaptation to climate change only through the interplay of technical innovation, ecological understanding, the expertise of government agencies and societal acceptance,” says Prof. Schlurmann.
Final report for the “Gute Küste Niedersachsen” (Good Coast – Lower Saxony) project: https://doi.org/10.15488/20269
Note to editors:
For further information, please contact Jan-Michael Schönebeck at the Ludwig Franzius Institute of Hydraulic, Estuarine and Coastal Engineering: schoenebeck@lufi.uni-hannover.de
