Sandy coastlines are dynamic environments with potential for biodiverse habitats, such as green beaches. Green beach vegetation can develop on nutrient-poor beaches landward from embryo dunes. It is characterised by low-dynamic coastal wetland habitat such as salt marshes and dune slacks. It has been hypothesised that the establishment of green beach vegetation is facilitated by the shelter provided by embryo dunes, however evidence is lacking.

We explored the importance of geomorphology and soil conditions on the species richness and turnover of green beach vegetation over a time period of 10 years. We recorded 107 plots along 11 transects over a gradient from beach to dune on the island of Schiermonnikoog, the Netherlands. We characterised transect geomorphology at transect level and soil conditions and vegetation at plot level in 2006 and 2016.

We found that the green beach vegetation was highly dynamic, total plant cover increased by 62% within 10 years. In 2006 beach width was an important factor in explaining species richness, with the highest number of species occurring on narrow beaches with a large volume of embryo dunes. In 2016, species richness was positively associated with the build-up of organic matter. Overall species richness declined relative to 2006 and was accompanied by an increase in elevation due to sand burial and the expansion of embryo dune volume.

Our data suggests that geomorphology influenced the vegetation indirectly by affecting sand burial rate. Plant species richness declined less at sheltered conditions where sand burial was limited, allowing the build-up of organic matter. This indicates a time-dependent relationship between the development of embryo dunes and plant species richness: embryo dunes can be a source of shelter, thus increasing species richness, but can compete for space over time, lowering species richness again. Our results are relevant for engineering and management of biodiverse sandy shores.

沙质海岸线是具有生物多样性栖息地潜力的动态环境，例如绿色海滩。绿色海滩植被可以在营养贫乏的海滩上从胚胎沙丘向陆发展。它的特点是低动态的沿海湿地栖息地，如盐沼和沙丘。已经假设胚胎沙丘提供的庇护所促进了绿色海滩植被的建立，但缺乏证据。

我们探讨了地貌和土壤条件对 10 年时间段内绿色海滩植被的物种丰富度和周转的重要性。我们在荷兰 Schiermonnikoog 岛上从海滩到沙丘的梯度上沿 11 个横断面记录了 107 个地块。我们在 2006 年和 2016 年表征了样带水平的样带地貌和样地水平的土壤条件和植被。

我们发现绿色海滩植被高度动态，10 年内植物总覆盖增加了 62%。2006 年，海滩宽度是解释物种丰富度的一个重要因素，在具有大量胚胎沙丘的狭窄海滩上出现的物种数量最多。2016 年，物种丰富度与有机物质的积累呈正相关。总体物种丰富度相对于 2006 年有所下降，同时由于沙埋和胚胎沙丘体积的扩大而导致海拔升高。

我们的数据表明，地貌通过影响沙埋率间接影响植被。在沙土埋藏有限的遮蔽条件下，植物物种丰富度下降较少，从而允许有机物质的积累。这表明胚沙丘的发育与植物物种丰富度之间存在时间依赖关系：胚沙丘可以作为庇护所，从而增加物种丰富度，但会随着时间的推移争夺空间，再次降低物种丰富度。我们的结果与生物多样性沙滩的工程和管理相关。