Development of Rich Fen on the SE Baltic Coast, Latvia, during the Last 7500 Years, Using Paleoecological Proxies: Implications for Plant Community Development and Paleoclimatic Research

We present the paleoecological development of a rich fen located in the dune area on the SE Baltic coast, during the last 7500 years. The Apuciems Mire hosts rare and endangered plant communities in Europe, such as Schoenus ferrugineus and Cladium mariscus. Analysis at high-resolution of plant macroremains in two peat cores was carried out to reconstruct local vegetation succession and fluctuations in moisture availability on the peatland, while a pollen record was developed to reconstruct plant succession, moisture variability and human activity at the regional scale. Based on the presence or the absence of macroremains of plants that occur in wet habitat e.g. Cladium mariscus, Schoenoplectus tabernaemontani, Alisma plantago-aquatica and Botrycoccocus we distinguished four wet periods ca. 6000, 2000, 1750-1550, 1200-150 cal yr. BP and four dry periods (ca. 7000, 4600-4200, 1800-1750, 1550-1200 cal yr. BP) in the peatland's development. A water level increase at 1200 cal yr. BP triggered the development of plant communities containing Chara sp., Schoenoplectus tabernaemontani, then Cladium mariscus. Our study shows a link between climate change at the regional scale and vegetation development in Apuciems Mire. We showed that changes in vegetation structure during last 150 years was caused by drainage and human activity.