The Population of the Glacial Relict Betula nana Surviving Anthropogenic Pressure (the Case of Šepeta Peatland in Northeastern Lithuania)

The main objective of the study was to evaluate the population characteristics of Betula nana under different anthropogenic influences. The study was conducted in the vicinity of the exploited Šepeta peatland (northeastern Lithuania). The population status of B. nana was determined by comparing the ramet density and morphology (height, branching, and leaf size), the age structure, the number of generative ramets, and their flowering characteristics in four study areas at different distances from the exploited peatlands and in different habitats. Around 20 environmental factors were included in the analysis, covering water levels, peat, and vegetation characteristics. Shading, drainage and increased amounts of nitrogen in the habitats are the main factors contributing to the differences and structure of B. nana cenopopulations. Although taller ramets with larger leaves are observed under the changed conditions as an adaptation to shading, the negative anthropogenic effects in the most affected habitats are reflected in a reduction in the number of flowering ramets, lower vegetative regeneration, and an increase in the number of dead twigs on mature ramets.