title: Vegetation as self-adaptive coastal protection: Reduction of current velocity and morphologic plasticity of a brackish marsh pioneer.
abstract: By reducing current velocity, tidal marsh vegetation can diminish storm surges and storm waves. Conversely, currents often exert high mechanical stresses onto the plants and hence affect vegetation structure and plant characteristics. In our study, we aim at analysing this interaction from both angles. On the one hand, we quantify the reduction of current velocity by Bolboschoenus maritimus, and on the other hand, we identify functional traits of B. maritimus' ramets along environmental gradients. Our results show that tidal marsh vegetation is able to buffer a large proportion of the flow velocity at currents under normal conditions. Cross-shore current velocity decreased with distance from the marsh edge and was reduced by more than 50% after 15 m of vegetation. We were furthermore able to show that plants growing at the marsh edge had a significantly larger diameter than plants from inside the vegetation. We found a positive correlation between plant thickness and cross-shore current which could provide an adaptive value in habitats with high mechanical stress. With the adapted morphology of plants growing at the highly exposed marsh edge, the entire vegetation belt is able to better resist the mechanical stress of high current velocities. This self-adaptive effect thus increases the ability of B. maritimus to grow and persist in the pioneer zone and may hence better contribute to ecosystem-based coastal protection by reducing current velocity.
authors.affiliation: Environmental Systems Analysis Institute of Geoecology Technische Universität Braunschweig Langer Kamp 19c 38106 Braunschweig Germany; Institute of Earth and Environmental Sciences University of Potsdam Karl-Liebknecht-Str. 24-2514476 Potsdam Germany.
authors.forename: Jana
authors.initials: J
authors.lastname: Carus
authors.affiliation: Environmental Systems AnalysisInstitute of Geoecology Technische Universität Braunschweig Langer Kamp 19c 38106 Braunschweig Germany; Forschungszentrum Küste Merkurstr. 1130419 Hannover Germany.
authors.forename: Maike
authors.initials: M
authors.lastname: Paul
authors.affiliation: Environmental Systems AnalysisInstitute of Geoecology Technische Universität Braunschweig Langer Kamp 19c 38106 Braunschweig Germany; Berlin-Brandenburg Institute of Advanced Biodiversity Research (BBIB) Berlin Germany.
authors.forename: Boris
authors.initials: B
authors.lastname: Schröder
keywords: Adaptive value; Bolboschoenus maritimus; brackish marsh; flow velocity; mechanical pressure; morphological adaptation; phenotypic plasticity; pioneer zone