Vegetation as self-adaptive coastal protection: reduction of current velocity and morphologic plasticity of a brackish marsh pioneer

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...潮滩湿地植被可通过降低水流流速削弱风暴潮与风暴浪。反之，水流常对植物施加高强度机械应力，进而影响植被结构与植株性状。本研究旨在从双向视角解析这一互作关系：一方面量化海三棱藨草（Bolboschoenus maritimus）对水流流速的削弱效果，另一方面识别沿环境梯度分布的海三棱藨草分株功能性状。研究结果表明，常态水流条件下，潮滩湿地植被可缓冲大部分流速。垂岸流速随距滩涂边缘距离的增加而降低，经15米植被带后流速降幅超过50%。此外，本研究还发现，生长于滩涂边缘的植株直径显著大于植被带内部的植株；同时植株粗度与垂岸流速呈正相关关系……