Peat palaeorecords from the arid Caspian Lowland in Russia: Environmental and anthropogenic effects during the second half of the Holocene

The current study presents new palaeoecological records from arid areas in the western sector of the Caspian Lowland, covering the second half of the Holocene. Environmental alterations, driven by global climatic factors and regional features initiated by the Caspian Sea, were identified based on palynological and sedimentological changes in two mires. The study revealed that the wetlands in the south and northwest of the Caspian Lowland have different origins and sources of water supply because they are associated with the priority influence of the Caspian Sea (i.e. Arkida mire) or the dynamics of winter-cyclonic precipitation (i.e. Zelmen mire). Therefore, the humidification episodes in the peatlands under consideration were rarely synchronous. In the south of the Caspian Lowland adjacent to the Caucasus, the climate was milder, steppe vegetation predominated, and the most favourable intervals were at about 4.1-3.8, 3.4-2.8, 2.3-2.9 and after 1.5 cal ka BP. Apparently, the moisturising influence of the Caspian Sea was decisive there, even during the strengthening of the high-pressure zone in Siberia, resulting in a decreased role of westerlies and dryness in other regions. The northeast of the Caspian Lowland was distinguished by longer arid episodes and a more significant contribution of semi-desert vegetation. An increase in moisture and steppe predominance detected there at intervals of 6.7, 3.8, 2.8-2.4, and several shorter ones after 1.4 cal ka BP is associated with warm and humid winters that coincided with a weak Siberian High and North Atlantic warming combined with Caspian transgression. Wetlands in arid areas were vulnerable to intensive human activity over thousands of years and were involved in year-round grazing cycles, even during dry periods. Peculiarities of paleoecological records reflect the burning and forced grazing on the mire under aridification, evident signs of overgrazing, and the use of swamp herbs for building purposes. (C) 2022 Elsevier Ltd. All rights reserved.

Automated summary

This study presents new palaeoecological records from arid areas in the western sector of the Caspian Lowland, highlighting the environmental alterations driven by global climatic factors and regional features initiated by the Caspian Sea. The origins and water sources of wetlands in the region vary based on their association with the Caspian Sea or winter-cyclonic precipitation. The paleoecological records suggest that wetlands in arid areas have undergone significant changes due to intensive human activity, including burning, overgrazing, and the use of swamp herbs for construction purposes.