The current climate crisis is associated with rising sea levels, which raises the concerning prospect of losing coastal ecosystems, such as salt marshes. Where inland migration is impossible, salt marshes will only persist if their vertical accretion exceeds the rate of sea-level rise. Positive vertical accretion is mainly driven by sedimentation, whereas negative vertical accretion is driven by erosion and soil compaction, among others. These processes can be influenced by abiotic and biotic factors. The biotic factors, best described by plant functional traits of the salt-marsh vegetation, are, however, not well understood. We assembled a large dataset of 336 plots with vertical accretion time series and plant abundances and coupled it with trait data from salt marsh species of the German Wadden Sea, covering natural unmanaged, anthropogenic unmanaged, and grazed marshes. By using multiple logistic regression analyses, we studied the effects of plant functional traits and distance to the marsh edge on vertical accretion. Mean vertical accretion was in the range of recent sea level rise, except for plots on elevated grazed marshes. There were, however, pronounced local differences in vertical accretion. Positive accretion increased with distance to marsh edge and increasing leaf and stem roughness, described by specific stem length, canopy height, stem mass, leaf mass and leaf area. Except on grazed marshes, leaf traits contributed more strongly to the explanation of positive accretion than stem traits. Negative accretion by e.g., erosion was facilitated by low specific root length and low root and rhizome mass, i.e., lower anchoring capacity. To better assess coastal resilience to sea level rise, our findings suggest (i) to include these effect traits in models and experimental analyses of salt marsh vertical accretion and (ii) to consider effects of vegetation roughness on accretion in salt marsh management schemes.

当前的气候危机与海平面上升有关，这增加了失去沿海生态系统（如盐沼）的担忧。在不可能向内陆迁移的地方，盐沼只有在垂直增长超过海平面上升速度的情况下才会持续存在。正垂直吸积主要由沉积驱动，而负垂直吸积主要由侵蚀和土壤压实等驱动。这些过程可能受到非生物和生物因素的影响。然而，由盐沼植被的植物功能性状最好地描述的生物因素尚不清楚。我们组装了一个包含 336 个地块的大型数据集，其中包含垂直吸积时间序列和植物丰度，并将其与德国瓦登海盐沼物种的性状数据相结合，涵盖自然未管理、人为的无人管理和放牧的沼泽。通过使用多元逻辑回归分析，我们研究了植物功能性状和到沼泽边缘的距离对垂直吸积的影响。平均垂直加积在最近海平面上升的范围内，除了高架放牧沼泽上的地块。然而，垂直吸积存在明显的局部差异。正吸积随着到沼泽边缘的距离和叶和茎粗糙度的增加而增加，通过特定的茎长、冠层高度、茎质量、叶质量和叶面积来描述。除了在放牧的沼泽地，叶子特征比茎特征更能解释正增长。较低的比根长度和较低的根和根茎质量（即较低的锚定能力）促进了由侵蚀引起的负增长。