Abstract:
In order to evaluate the sensitivity of aquatic and terrestrial ecosystems to climatic changes, lithological (sediment structure and color, grain size, physical properties) and biochemical (TOC, TOC/TN, d13C of TOC and carbonates) investigations were carried out on an 11.12 m-long sediment core from Lama Lake (Central Siberia, Putorana Plateau). According to the pollen data, the sequence represents the termination of the Pleistocene, and the entire Holocene. It is composed of highly terrigenous and stratified clays and silts. Sediment structure, grain-size distribution, carbonate contents and physical properties of the sediment indicate that glaciers were present in the catchment area of Lama Lake during the period Oldest Dryas to Allerød. For the same time period, d13C values of TOC give indications of a perennial ice cover. Since the Allerød, organic matter accumulation has increased, caused by an increasing input of land vegetation and aquatic primary production as revealed by relations TOC contents, TOC/TN ratios and d13C values of TOC. During the Holocene climatic optimum, in late Preboreal and Boreal times, biogenic primary production in Lama Lake reached its maximum and the vegetation in the catchment area changed from grassy tundra to a dense forest. From the Atlantic period to the present, small variations in d13C values of TOC and TOC contents are probably related to the location of Lama Lake on the border between grass and wooded steppe, leading to responses of environmental conditions to even small changes in climate.