Susceptibility of small boreal lakes to environmental changes as inferred from organic sediments of Lake Talvilampi (Finland)

Abstract

During the Holocene, multiple thermal changes commonly occurred in the northern hemisphere. They are well-recorded in lakes with minimum human impact from the Arctic Circle area. The development of these lakes reflects ecological and climatic changes occurring from the formation of the lakes until present-day times. All environmental fluctuations affect biodiversity and are reflected in the number and composition of species. The goals of this study were to detect the ecological changes in a small Finnish lake using pollen, Cladocera and geochemical analyses. The research area is located within the northern zone of boreal coniferous forest and is the most sparsely populated region of Finland. The lake is located in Kuusamo uplands, E Finland, near the polar circle and over 20 km from the Russian border. Indicators of cold water were found only during the initial stage, after the 8.2 ka event and then the temperature was higher. Trophy was high at the beginning of the lake development and then a significant increase in trophy was found after 2600 BP. The impact of human activity is hardly traceable in Arctic Circle Finland throughout the Holocene Thermal Maximum. During the late-Holocene (after 4200 yr cal. BP), this impact is still weak and, even as late as the 20th century, only a few traces of human activity are recorded. General conclusion is that long-term climatic shift has been the most important factor driving changes in the limnology of Lake Talvilampi.