Microrefugia - limiting factors and unique synergy of environment

Peatlands are a very important ecosystem which are characterized by distinctive vegetation, hydrology, and local climate. In the last decades, much effort was made a better understanding of microrefugia and their importance. Nevertheless, we still have little knowledge about the histories of the refugia. In the day of rapid climate change and increasing anthropogenic pressure, knowledge about the history of sites that represent a refugium of flora or fauna is a key aspect. The aim of this study is reconstructing the history of the glacial relict Betula nana in northern Poland located far from the southern range of its natural distribution. We suppose that the persistence of Betula nana is driven by a) the morphology and geology of the catchment, b) the maintenance of open vegetation on the peatland surface and c) exceptional microclimatic and hydrological conditions. Here, based on recent eco-hydrological monitoring and long-term palaeoecological proxy we try to be understated postglacial refugia of Betula nana from Central Europe (Linje mire). Detailed research was carried out on the peat profile using pollen analysis, to reconstruct the presence of open habitat on the mire during the Holocene. Pollen and macrofossils analysis revealed a continuous presence of Betula nana in the postglacial history of the peatland. Palaeoecological results show the variable situation of the Betula nana population in the peatland over the past 12 ka, indicating a strong relationship between paleohydrology and changes in the occurrence of this species. Our results of 12 years of local monitoring indicated that the mire is characterized by specific local climate and diverse water table depth. A synergy of local relief, microclimates, hydrology, and geology of the catchment affects the Betula nana population during the post-glacial history.