TY - JOUR A1 - Aichner, Bernhard A1 - Herzschuh, Ulrike A1 - Wilkes, Heinz A1 - Schulz, Hans-Martin A1 - Wang, Yongbo A1 - Plessen, Birgit A1 - Mischke, Steffen A1 - Diekmann, Bernhard A1 - Zhang, Chengjun T1 - Ecological development of Lake Donggi Cona, north-eastern Tibetan Plateau, since the late glacial on basis of organic geochemical proxies and non-pollen palynomorphs JF - Palaeogeography, palaeoclimatology, palaeoecology : an international journal for the geo-sciences N2 - Organic geochemical proxy data from surface sediment samples and a sediment core from Lake Donggi Cona were used to infer environmental changes on the northeastern Tibetan Plateau spanning the last 18.4 kyr. Long-chain n-alkanes dominate the aliphatic hydrocarbon fraction of the sediment extract from most surface sediment samples and the sediment core. Unsaturated mid-chain n-alkanes (nC(23:1) and nC(25:1)) have high abundances in some samples, especially in core samples from the late glacial and early Holocene. TOC contents, organic biomarker and non-pollen-palynomorph concentrations and results from organic petrologic analysis on selected samples suggest three major episodes in the history of Lake Donggi Cona. Before ca. 12.6 cal ka BP samples contain low amounts of organic matter due to cold and arid conditions during the late glacial. After 12.6 cal ka BP, relatively high contents of TOC and concentrations of Botryococcus fossils, as well as enhanced concentrations of mid-chain n-alkanes and n-alkenes suggest a higher primary and macrophyte productivity than at present This is supported by high contents of palynomorphs derived from higher plants and algae and was possibly triggered by a decrease of salinity and amelioration of climate during the early Holocene. Since 6.8 cal ka BP Lake Donggi Cona has been an oligotrophic freshwater lake. Proxy data suggest that variations in insolation drive ecological changes in the lake, with increased aquatic productivity during the early Holocene summer insolation maximum. Short-term drops of TOC contents or biomarker concentrations (at 9.9 cal ka BP, after 8.0 and between 3.5 and 1.7 cal ka BP) can possibly be related to relatively cool and dry episodes reported from other sites on the north-eastern Tibetan Plateau, which are hypothesized to occur in phase with Northern Hemisphere cooling events. KW - Biomarker KW - Holocene KW - n-alkanes KW - Total organic carbon KW - Organic matter KW - Macerals KW - Aquatic macrophytes Y1 - 2012 U6 - https://doi.org/10.1016/j.palaeo.2011.10.015 SN - 0031-0182 VL - 313 IS - 2 SP - 140 EP - 149 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Bernhard, Nadine A1 - Moskwa, Lisa-Marie A1 - Schmidt, Karsten A1 - Oeser, Ralf Andreas A1 - Aburto, Felipe A1 - Bader, Maaike Y. A1 - Baumann, Karen A1 - von Blanckenburg, Friedhelm A1 - Boy, Jens A1 - van den Brink, Liesbeth A1 - Brucker, Emanuel A1 - Buedel, Burkhard A1 - Canessa, Rafaella A1 - Dippold, Michaela A. A1 - Ehlers, Todd A1 - Fuentes, Juan P. A1 - Godoy, Roberto A1 - Jung, Patrick A1 - Karsten, Ulf A1 - Koester, Moritz A1 - Kuzyakov, Yakov A1 - Leinweber, Peter A1 - Neidhardt, Harald A1 - Matus, Francisco A1 - Mueller, Carsten W. A1 - Oelmann, Yvonne A1 - Oses, Romulo A1 - Osses, Pablo A1 - Paulino, Leandro A1 - Samolov, Elena A1 - Schaller, Mirjam A1 - Schmid, Manuel A1 - Spielvogel, Sandra A1 - Spohn, Marie A1 - Stock, Svenja A1 - Stroncik, Nicole A1 - Tielboerger, Katja A1 - Uebernickel, Kirstin A1 - Scholten, Thomas A1 - Seguel, Oscar A1 - Wagner, Dirk A1 - Kühn, Peter T1 - Pedogenic and microbial interrelations to regional climate and local topography BT - New insights from a climate gradient (arid to humid) along the Coastal Cordillera of Chile JF - Catena : an interdisciplinary journal of soil science, hydrology, geomorphology focusing on geoecology and landscape evolution N2 - The effects of climate and topography on soil physico-chemical and microbial parameters were studied along an extensive latitudinal climate gradient in the Coastal Cordillera of Chile (26 degrees-38 degrees S). The study sites encompass arid (Pan de Azucar), semiarid (Santa Gracia), mediterranean (La Campana) and humid (Nahuelbuta) climates and vegetation, ranging from arid desert, dominated by biological soil crusts (biocrusts), semiarid shrubland and mediterranean sclerophyllous forest, where biocrusts are present but do have a seasonal pattern to temperate-mixed forest, where biocrusts only occur as an early pioneering development stage after disturbance. All soils originate from granitic parent materials and show very strong differences in pedogenesis intensity and soil depth. Most of the investigated physical, chemical and microbiological soil properties showed distinct trends along the climate gradient. Further, abrupt changes between the arid northernmost study site and the other semi-arid to humid sites can be shown, which indicate non-linearity and thresholds along the climate gradient. Clay and total organic carbon contents (TOC) as well as Ah horizons and solum depths increased from arid to humid climates, whereas bulk density (BD), pH values and base saturation (BS) decreased. These properties demonstrate the accumulation of organic matter, clay formation and element leaching as key-pedogenic processes with increasing humidity. However, the soils in the northern arid climate do not follow this overall latitudinal trend, because texture and BD are largely controlled by aeolian input of dust and sea salts spray followed by the formation of secondary evaporate minerals. Total soil DNA concentrations and TOC increased from arid to humid sites, while areal coverage by biocrusts exhibited an opposite trend. Relative bacterial and archaeal abundances were lower in the arid site, but for the other sites the local variability exceeds the variability along the climate gradient. Differences in soil properties between topographic positions were most pronounced at the study sites with the mediterranean and humid climate, whereas microbial abundances were independent on topography across all study sites. In general, the regional climate is the strongest controlling factor for pedogenesis and microbial parameters in soils developed from the same parent material. Topographic position along individual slopes of limited length augmented this effect only under humid conditions, where water erosion likely relocated particles and elements downward. The change from alkaline to neutral soil pH between the arid and the semi-arid site coincided with qualitative differences in soil formation as well as microbial habitats. This also reflects non-linear relationships of pedogenic and microbial processes in soils depending on climate with a sharp threshold between arid and semi-arid conditions. Therefore, the soils on the transition between arid and semi-arid conditions are especially sensitive and may be well used as indicators of long and medium-term climate changes. Concluding, the unique latitudinal precipitation gradient in the Coastal Cordillera of Chile is predestined to investigate the effects of the main soil forming factor - climate - on pedogenic processes. KW - Climate KW - Topography KW - Soil texture KW - Total organic carbon KW - Carbon isotope ratio (delta C-13(TOC)) KW - Microbial abundance Y1 - 2018 U6 - https://doi.org/10.1016/j.catena.2018.06.018 SN - 0341-8162 SN - 1872-6887 VL - 170 SP - 335 EP - 355 PB - Elsevier CY - Amsterdam ER -