Abstract This study is the first overview of the floristic diversity of Bulgarian coastal dunes in terms of the presence of typical psammophytic or non-psammophytic plant species. It also aims to reveal changes in sand dune flora over time, based on own samples and existing data from previous studies. Our original floristic data was extracted from 154 phytosociological plots sampled in 12 large dune systems during 2017. All available literature sources were compiled to derive a list of vascular plants recorded for Bulgarian coastal dunes between 1905 and 2016. Due to the different scientific approaches applied in previous publications we split the studies into three periods over time: (I period: 1905 1950; II period: 1951–1990; III period: 1991–2016), and separate lists were also prepared for each. All vascular plants were assigned to one of five groups, according to their general habitat preference: 1) psammophytes, 2) weeds and ruderals, 3) grass- and shrubland plants, 4) forests plants and 5) alien (including invasive) species. The full species list comprises 501 taxa, and the highest number of species was compiled from publications after 1990. Across all periods and studied dune complexes, grass- and shrubland plants were most abundant, while other non-psammophyte species groups showed low presence. A comparison of data from 2003 and 2015 showed that species richness of psammophytes decreased over time, which is in contrast to the average number of weeds and ruderals, and particularly to species richness of grass- and shrubland species. Our results show that a core group of characteristic psammophytes remains constant through all study periods. Alien (including invasive) species still are limited in abundance but there is an alarming recent increase in their numbers. We believe that our synthesis will be of use for further floristic inventories of Pontic sand dunes.

中文翻译：

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保加利亚黑海沿岸沙丘植物群的现状和历史记录

摘要 本研究首次根据典型砂生植物或非砂生植物物种的存在，对保加利亚沿海沙丘的植物多样性进行了概述。它还旨在根据自己的样本和先前研究的现有数据揭示沙丘植物群随时间的变化。我们的原始植物区系数据是从 2017 年在 12 个大型沙丘系统中采样的 154 个植物社会学地块中提取的。所有可用的文献来源都经过汇编，以得出 1905 年至 2016 年间保加利亚沿海沙丘记录的维管植物列表。由于在在之前的出版物中，我们将研究分为三个时期：（I 时期：1905 1950；II 时期：1951-1990；III 时期：1991-2016），并且还为每个时期准备了单独的列表。根据它们的一般栖息地偏好，所有维管植物被分配到五个组中的一个：1) 砂生植物，2) 杂草和草本植物，3) 草和灌木植物，4) 森林植物和 5) 外来（包括入侵）物种。完整的物种清单包括 501 个分类群，最多的物种是从 1990 年之后的出版物中汇编的。在所有时期和研究的沙丘复合体中，草和灌木植物最丰富，而其他非砂生植物物种组的存在率较低。2003 年和 2015 年的数据比较表明，沙生植物的物种丰富度随着时间的推移而下降，这与杂草和杂草的平均数量形成鲜明对比，尤其是与草和灌木物种的物种丰富度形成​​鲜明对比。我们的结果表明，在所有研究期间，特征沙生植物的核心组都保持不变。外来（包括入侵）物种的数量仍然有限，但最近它们的数量出现了惊人的增长。我们相信我们的合成将用于 Pontic 沙丘的进一步植物区系清单。