TY - JOUR A1 - Zibulski, Romy A1 - Herzschuh, Ulrike A1 - Pestryakova, Luidmila Agafyevna A1 - Wolter, Juliane A1 - Mueller, S. A1 - Schilling, N. A1 - Wetterich, Sebastian A1 - Schirrmeister, Lutz A1 - Tian, Fang T1 - River flooding as a driver of polygon dynamics: modern vegetation data and a millennial peat record from the Anabar River lowlands (Arctic Siberia) JF - Biogeosciences N2 - The spatial and temporal variability of a low-centred polygon on the eastern floodplain area of the lower Anabar River (72.070 degrees N, 113.921 degrees E; northern Yakutia, Siberia) has been investigated using a multi-method approach. The present-day vegetation in each square metre was analysed, revealing a community of Larix, shrubby Betula, and Salix on the polygon rim, a dominance of Carex and Andromeda polifolia in the rim-to-pond transition zone, and a predominantly monospecific Scorpidium scorpioides coverage within the pond. The total organic carbon (TOC) content, TOC/TN (total nitrogen) ratio, grain size, vascular plant macrofossils, moss remains, diatoms, and pollen were analysed for two vertical sections and a sediment core from a transect across the polygon. Radiocarbon dating indicates that the formation of the polygon started at least 1500 yr ago; the general positions of the pond and rim have not changed since that time. Two types of pond vegetation were identified, indicating two contrasting development stages of the polygon. The first was a well-established moss association, dominated by submerged or floating Scorpidium scorpioides and/or Drepanocladus spp. and overgrown by epiphytic diatoms such as Tabellaria flocculosa and Eunotia taxa. This stage coincides temporally with a period in which the polygon was only drained by lateral subsurface water flow, as indicated by mixed grain sizes. A different moss association occurred during times of repeated river flooding (indicated by homogeneous medium-grained sand that probably accumulated during the annual spring snowmelt), characterized by an abundance of Meesia triquetra and a dominance of benthic diatoms (e. g. Navicula vulpina), indicative of a relatively high pH and a high tolerance of disturbance. A comparison of the local polygon vegetation (inferred from moss and macrofossil spectra) with the regional vegetation (inferred from pollen spectra) indicated that the moss association with Scorpidium scorpioides became established during relatively favourable climatic conditions, while the association dominated by Meesia triquetra occurred during periods of harsh climatic conditions. Our study revealed a strong riverine influence (in addition to climatic influences) on polygon development and the type of peat accumulated. Y1 - 2013 U6 - https://doi.org/10.5194/bg-10-5703-2013 SN - 1726-4170 VL - 10 IS - 8 SP - 5703 EP - 5728 PB - Copernicus CY - Göttingen ER - TY - JOUR A1 - Herzschuh, Ulrike A1 - Pestryakova, Luidmila Agafyevna A1 - Savelieva, Larissa A. A1 - Heinecke, Liv A1 - Böhmer, Thomas A1 - Biskaborn, Boris A1 - Andreev, Andrei A1 - Ramisch, Arne A1 - Shinneman, Avery L. C. A1 - Birks, H. John B. T1 - Siberian larch forests and the ion content of thaw lakes form a geochemically functional entity JF - Nature Communications N2 - Siberian larch forests growing on shallow permafrost soils have not, until now, been considered to be controlling the abiotic and biotic characteristics of the vast number of thaw-lake ecosystems. Here we show, using four independent data sets (a modern data set from 201 lakes from the tundra to taiga, and three lake-core records), that lake-water geochemistry in Yakutia is highly correlated with vegetation. Alkalinity increases with catchment forest density. We postulate that in this arid area, higher evapotranspiration in larch forests compared with that in the tundra vegetation leads to local salt accumulation in soils. Solutes are transported to nearby thaw lakes during rain events and snow melt, but are not fully transported into rivers, because there is no continuous groundwater flow within permafrost soils. This implies that potentially large shifts in the chemical characteristics of aquatic ecosystems to known warming are absent because of the slow response of catchment forests to climate change. Y1 - 2013 U6 - https://doi.org/10.1038/ncomms3408 SN - 2041-1723 VL - 4 PB - Nature Publ. Group CY - London ER - TY - JOUR A1 - Klemm, Juliane A1 - Herzschuh, Ulrike A1 - Pisaric, Michael F. J. A1 - Telford, Richard J. A1 - Heim, Birgit A1 - Pestryakova, Luidmila Agafyevna T1 - A pollen-climate transfer function from the tundra and taiga vegetation in Arctic Siberia and its applicability to a Holocene record JF - Palaeogeography, palaeoclimatology, palaeoecology : an international journal for the geo-sciences N2 - This study aims to establish, evaluate, and apply a modern pollen-climate transfer function from the transition zone between arctic tundra and light-needled taiga in Arctic Siberia. Lacustrine samples (n = 96) from the northern Siberian lowlands of Yakutia were collected along four north-to-south transects crossing the arctic forest line. Samples span a broad temperature and precipitation gradient (mean July temperature, T-July: 7.5-18.7 degrees C; mean annual precipitation, P-ann: 114-315 mm/yr). Redundancy analyses are used to examine the relationship between the modern pollen signal and corresponding vegetation types and climate. Performance of transfer functions for T-July and P-ann were cross-validated and tested for spatial autocorrelation effects. The root mean square errors of prediction are 1.67 degrees C for T-July and 40 mm/yr for P-ann. A climate reconstruction based on fossil pollen spectra from a Siberian Arctic lake sediment core spanning the Holocene yielded cold conditions for the Late Glacial (1-2 degrees C below present T-July). Warm and moist conditions were reconstructed for the early to mid Holocene (2 degrees C higher T-July than present), and climate conditions similar to modern ones were reconstructed for the last 4000 years. In conclusion, our modern pollen data set fills the gap of existing regional calibration sets with regard to the underrepresented Siberian tundra-taiga transition zone. The Holocene climate reconstruction indicates that the temperature deviation from modern values was only moderate despite the assumed Arctic sensitivity to present climate change. KW - Mean July temperature KW - Reconstruction KW - Weighted-average partial least squares KW - Autocorrelation KW - Yakutia Y1 - 2013 U6 - https://doi.org/10.1016/j.palaeo.2013.06.033 SN - 0031-0182 SN - 1872-616X VL - 386 SP - 702 EP - 713 PB - Elsevier CY - Amsterdam ER -