Monitoring Impact of Salt-Marsh Vegetation Characteristics on Sedimentation: an Outlook for Nature-Based Flood Protection

• Published in: Wetlands (Wilmington, N.C.) Vol. 41; no. 6; p. 76
• Main Authors: Baaij, B. Martina, Kooijman, Jeroen, Limpens, Juul, Marijnissen, Richard J. C., van Loon-Steensma, Jantsje M.
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01-08-2021; Springer Nature B.V
• Subjects: Aquatic plants; Biomass; Biomedical and Life Sciences; Coastal Sciences; Coastal Wetlands; Creeks & streams; Density; Diameters; Ecology; Environmental Management; Experiments; Flood control; Flood management; Flood protection; Floods; Flow velocity; Flowers & plants; Freshwater & Marine Ecology; Grain size; Grain size distribution; Height; Human influences; Hydrogeology; Landscape Ecology; Life Sciences; Natural vegetation; Particle size; Salt marshes; Sea level; Sea level rise; Sedimentation; Sedimentation & deposition; Sediments; Size distribution; Soil erosion; Stems; Vegetation; Vegetation type; Wave attenuation; Wave energy; Wave power; Netherlands; Grain size; Sediment deposition; Biomass; Wave damping; Vegetation type; Vegetation structure
• ISSN: 0277-5212; 1943-6246
• DOI: 10.1007/s13157-021-01467-w

Salt marshes can protect coastlines against flooding by attenuating wave energy and enhancing shoreline stabilization. However, salt-marsh functioning is threatened by human influences and sea level rise. Although it is known that protection services are mediated by vegetation, little is known about the role of vegetation structure in salt-marsh accretion. We investigated the role of vegetation presence, vegetation type and structural vegetation characteristics in sedimentation and sediment grain size. We established 56 plots on a salt marsh on the Dutch Wadden island of Texel. Plots were divided over four vegetation types contrasting in vegetation structure and varied in elevation and distance to creeks. Vegetation presence was controlled by clipping in subplots. Within each plot, we measured seven vegetation characteristics, sedimentation and the sediment grain size distribution. Furthermore, we explored the effect of the natural variation in vegetation structure on wave attenuation with a simple model approach. For this, we developed vegetation scenarios based on the field measurements of stem height, diameter and density. We found that vegetation presence increased sedimentation on average by 42%. Sedimentation was highest in
Salicornia
vegetation and increased with stem height and branching level. Grain size also seemed to increase with branching level. Modelled wave attenuation was 7.5 times higher with natural vegetation compared to topography only, was strongest for
Spartina
vegetation and most sensitive to the natural variance in stem density. Our results can be used to improve predictions of salt-marsh accretion and the implementation of salt marshes in nature-based flood defences.