Lake diatom response to climate change and sedimentary events on the southeastern Tibetan Plateau during the last millennium

• Published in: Quaternary science reviews Vol. 241; p. 106409
• Main Authors: Liao, Mengna, Herzschuh, Ulrike, Wang, Yongbo, Liu, Xingqi, Ni, Jian, Li, Kai
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.08.2020
• Subjects: Catchment-lake interaction; China; Community size structure; Current warm period; Little ice age; Pantocsekiella; Planktonic: benthic ratio; Little ice age; Current warm period; Pantocsekiella; China; Planktonic: benthic ratio; Community size structure; Catchment-lake interaction
• ISSN: 0277-3791; 1873-457X
• DOI: 10.1016/j.quascirev.2020.106409

Climate change on the southeastern Tibetan Plateau (TP) is assumed to impact lake ecosystems. However, parallel changes in climate and non-climate factors and mediation of signals by catchment processes complicate the assessment of climate-change effects on lake ecosystems requiring long-term and high resolution multi-variable time-series. Here we present a diatom record from sediments in the lake Basomtso, southeastern TP, covering the period 1083–2012 CE with sub-decadal resolution which we relate to available proxies for potential climate and non-climate factors. The record is dominated by planktonic species and the compositional change is mainly characterized by alternations between big- and small-celled Pantocsekiella ocellata and between planktonic and benthic diatom species. The diatom assemblages show a decrease of P. ocellata (big form) since the end of 17th century and an increase of P. ocellata (small form) as well as an increase in diatom productivity, reflecting changes on a centennial timescale which mainly follow temperature increase. We recorded several changes in the ratio of planktonic to benthic species abundance (P: B) on a sub-decadal or decadal timescale. Noticeable decreases in P: B were a result of rapid sedimentary events caused by high energy flows. Cross-correlation analyses reveal synchronous responses of diatoms and asynchronous responses of terrestrial vegetation to regional temperature change, indicating a higher potential of lake diatoms to detect the timing and magnitude of climate shifts on the southeastern TP. The results imply that aquatic ecosystems in Basomtso, as well as in other mountain lakes on the southeastern TP, are probably subject to a larger risk of regime shift than terrestrial ecosystems under future climate scenarios. Conceptual model of the effects of centennial-scale climate change and short-lived sedimentary events on diatom composition in Basomtso. Rising temperature promotes diatom productivity and favors small-cell planktonic species. The responses of terrestrial vegetation are slower than that of lacustrine diatoms which change synchronously with temperature. Sedimentary events caused by high-energy inflow or subaqueous slumps alter diatom composition by introducing more benthic diatoms from the catchment or the littoral zone. [Display omitted] •Rising temperature promotes diatom productivity and favor small-cell planktonic species.•Sedimentary events alter sediment diatom composition by introducing more benthic diatoms.•Terrestrial vegetation response to climate change slower than that of lacustrine diatoms.•Aquatic ecosystems are subject to a larger risk of regime shift than terrestrial ecosystems.