[M-IS01] Environmental, Socio-Economic and Climatic Changes in Northern Eurasia

[MIS01-14] Land use impacts on thermokarst lakes in Central Yakutia, Eastern Siberia

*Izabella Baisheva^1,2,4,7、Ramesh Glueckler^1,2,8、Amelie K. Stieg¹、Iris Eder¹、Aital Egorov⁴、Evgenii S. Zakharov^4,5、Lena A. Ushnitskaya⁴、Paraskovya V. Davydova⁴、Boris K. Biskaborn¹、Luidmila A. Pestryakova⁴、Sardana N. Levina⁴、Ruslan M. Gorodnichev⁴、Kathleen R. Stoof-Leichsenring¹、Birgit Heim¹、Antje Eulenburg⁶、Pier Paul Overduin⁶、Jorge García Molinos⁷、Ulrike Herzschuh^1,2,3 (1.Polar Terrestrial Environmental Systems, Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, Potsdam, Germany、2.Institute for Environmental Science and Geography, University of Potsdam, Potsdam, Germany 、3.Institute for Biochemistry and Biology, University of Potsdam, Potsdam, Germany 、4.Institute of Natural Sciences, North-Eastern Federal University of Yakutsk, Yakutsk, Russia、5.Institute for Biological Problems of Cryolithozone, Siberian Branch of Russian Academy of Sciences, Yakutsk, Russia、6.Permafrost Section, Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, Potsdam, Germany、7.Arctic Research Center, Hokkaido University, Sapporo, Japan 、8.Faculty of Environmental Earth Science, Hokkaido University, Sapporo, Japan )

キーワード：Thermokarst, Alaas lakes, sedDNA, hydrochemistry, Central Yakutia

Permafrost landscapes rich in ground ice are vulnerable to thaw and the formation of thermokarst lakes in response to climate warming. Thermokarst lakes have provided important aquatic habitats and biodiversity hotspots for thousands of years. Furthermore, they provide critical ecosystem services to the local communities, including fresh water supply, fishing and hunting grounds. In Central Yakutia, ground ice thawing causes a gradual deepening of permafrost active layer (thermokarst depression) and insufficient water supply then leads to the formation of alaas landscapes typical for the region. The formation of alaases has four main stages of development. At a final stage, alaas represents a meadow in a forest in a thermokarst depression with a residual lake (alaas lakes). Alaases have traditionally been associated with land-use for livestock production, including hay harvesting since the 14^th century, which has intensified during the course of the 20^th century and extended to crop production. The intensification of agriculture in alaas systems in the central Yakutian Lowlands in addition to global warming may irreversibly change water quality and biodiversity within the alaases, thus changing their ecosystem services and threatening the livelihood of local communities. Here we present the recent state of 51 lakes based on lake water chemistry and plant genetic metabarcoding analyses from lake surface sediments across Central Yakutia (average elevation 190 m a.s.l.). As a group, the 51 lakes span different types of formation stages and morphological development, exhibit a wide range of anthropogenic impacts and differ in alkalinity, ion composition, organic content and lake vegetation composition.