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    Ecosystem shifts at two Mid-Holocene tipping points in the alpine Lake Son Kol (Kyrgyzstan, Central Asia)

    Laug, A. and Schwarz, A. and Lauterbach, S. and Engels, Stefan and Schwalb, A. (2020) Ecosystem shifts at two Mid-Holocene tipping points in the alpine Lake Son Kol (Kyrgyzstan, Central Asia). The Holocene 30 (10), pp. 1410-1419. ISSN 0959-6836.

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    Tipping points can be defined as critical ecosystem thresholds that start self-enforced dynamics pushing systems into new stable states. Many lake ecosystems of arid Central Asia are sensitive to hydrological changes as they are located at the intersection of the influence of the dry Siberian Anticyclone and the relatively humid mid-latitude Westerlies, and their sediment records can be used to study past tipping points. We studied subfossil chironomid remains preserved in a ca. 6000-year-long sediment record from the Central Asian lake Son Kol (Central Kyrgyzstan) to reconstruct past ecosystem dynamics. Our results show abrupt transitions from a chironomid fauna dominated by macrophyte-associated, salinity-indicating taxa, to a vegetation-independent fauna, and subsequently to a macrophyte-associated, freshwater-indicating fauna. A comparison of the chironomid-based environmental reconstruction to other proxy indicators from the same record suggests a phase of increased Westerly strength starting about 4900 cal. yr BP. This increase led to enhanced precipitation and sediment fluxes into the lake, which in turn led to high turbidity levels and consequently to a macrophyte collapse causing abrupt changes in the chironomid fauna. At 4300 cal. yr BP, a weakening of the Westerlies in combination with higher lake levels led to lower turbidity and ultimately to the recovery of the macrophyte population and associated changes in the chironomid assemblage. These two sequences of events show how the occurrence of a gradual change in an external trigger (Westerlies) can trigger a cascade of within-lake processes (turbidity, macrophyte density) and may ultimately lead to an abrupt reorganisation of the ecosystem (chironomid fauna), providing models for tipping points.


    Item Type: Article
    School: Birkbeck Faculties and Schools > Faculty of Humanities and Social Sciences > School of Social Sciences
    Research Centres and Institutes: Research in Environment and Sustainability, Centre for
    Depositing User: Stefan Engels
    Date Deposited: 17 Apr 2020 11:03
    Last Modified: 10 May 2024 15:56


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