TY - JOUR A1 - Christ, Nicolas A1 - Immenhauser, Adrian A1 - Amour, Frederic A1 - Mutti, Maria A1 - Tomas, Sara A1 - Agar, Susan M. A1 - Alway, Robert A1 - Kabiri, Lahcen T1 - Characterization and interpretation of discontinuity surfaces in a Jurassic ramp setting (High Atlas, Morocco) JF - Sedimentology : the journal of the International Association of Sedimentologists N2 - Discontinuity surfaces are widely recognized but often poorly understood features of epeiric carbonate settings. In sedimentary systems, these features often represent hiatus surfaces below biostratigraphic resolution and may represent a considerable portion of the time contained in the sediment record. From an applied perspective, discontinuities may represent horizontal flow barriers and result in reservoir compartmentalization. Here, a total of 80 condensed surfaces (S1), firmgrounds (S2) and hardgrounds (S3) from a Jurassic (Middle and Upper Bajocian Assoul Formation) ramp setting of the High Atlas in Morocco are carefully documented with respect to their morphology, their secondary impregnation by Fe and Mn oxides and phosphates and their palaeoecological record. A statistical frequency distribution of two surfaces of the S1 type, 1.1 surfaces of the S2 type and 0.4 surfaces of the S3 type per 10 section metres is observed along a 220 m long carbonate succession. Based on two stratigraphically and spatially separated study windows and correlative sections, the stratigraphic frequency distribution, the lateral extent and the nature of facies change across discontinuities are documented in a quantitative manner. Specific features of the study site include the considerable stratigraphic thickness of the Assoul Formation and the conspicuous absence of subaerial-exposure-related features. Based on the data presented here, firmground and hardground surfaces are best interpreted as maximum-regression-related features. Relative sea-level lowstand results in a lowered wave base, and wave orbitals and currents result in sea floor omission and lithification. Care must be taken to avoid overly simplistic interpretations, as differences in bathymetry and carbonate facies result in marked changes in discontinuity characteristics in proximal-distal transects. The data shown here are of significance for those concerned with the interpretation of shoal water carbonate environments and are instrumental in the building of more realistic carbonate reservoir flow models. KW - Atlas Mountains KW - carbonate ramp KW - discontinuity surfaces KW - hardgrounds KW - hydrodynamic level KW - Jurassic KW - palaeoecology KW - relative sea-level Y1 - 2012 U6 - https://doi.org/10.1111/j.1365-3091.2011.01251.x SN - 0037-0746 VL - 59 IS - 1 SP - 249 EP - 290 PB - Wiley-Blackwell CY - Hoboken ER - TY - JOUR A1 - Tian, Fang A1 - Herzschuh, Ulrike A1 - Telford, Richard J. A1 - Mischke, Steffen A1 - Van der Meeren, Thijs A1 - Krengel, Michael T1 - A modern pollen-climate calibration set from central-western Mongolia and its application to a late glacial-Holocene record JF - Journal of biogeography N2 - AimFossil pollen spectra from lake sediments in central and western Mongolia have been used to interpret past climatic variations, but hitherto no suitable modern pollen-climate calibration set has been available to infer past climate changes quantitatively. We established such a modern pollen dataset and used it to develop a transfer function model that we applied to a fossil pollen record in order to investigate: (1) whether there was a significant moisture response to the Younger Dryas event in north-western Mongolia; and (2) whether the early Holocene was characterized by dry or wet climatic conditions. LocationCentral and western Mongolia. MethodsWe analysed pollen data from surface sediments from 90 lakes. A transfer function for mean annual precipitation (P-ann) was developed with weighted averaging partial least squares regression (WA-PLS) and applied to a fossil pollen record from Lake Bayan Nuur (49.98 degrees N, 93.95 degrees E, 932m a.s.l.). Statistical approaches were used to investigate the modern pollen-climate relationships and assess model performance and reconstruction output. ResultsRedundancy analysis shows that the modern pollen spectra are characteristic of their respective vegetation types and local climate. Spatial autocorrelation and significance tests of environmental variables show that the WA-PLS model for P-ann is the most valid function for our dataset, and possesses the lowest root mean squared error of prediction. Main conclusionsPrecipitation is the most important predictor of pollen and vegetation distributions in our study area. Our quantitative climate reconstruction indicates a dry Younger Dryas, a relatively dry early Holocene, a wet mid-Holocene and a dry late Holocene. KW - Central-western Mongolia KW - Lake Bayan Nuur KW - modern pollen KW - ordination KW - palaeoclimate reconstruction KW - palaeoecology KW - transfer functions KW - WA-PLS KW - Younger Dryas Y1 - 2014 U6 - https://doi.org/10.1111/jbi.12338 SN - 0305-0270 SN - 1365-2699 VL - 41 IS - 10 SP - 1909 EP - 1922 PB - Wiley-Blackwell CY - Hoboken ER - TY - GEN A1 - Battarbee, Richard W. A1 - Lamb, Henry F. A1 - Bennett, Keith A1 - Edwards, Mary A1 - Bjune, Anne E. A1 - Kaland, Peter E. A1 - Berglund, Björn E. A1 - Lotter, André F. A1 - Seppä, Heikki A1 - Willis, Kathy J. A1 - Herzschuh, Ulrike A1 - Birks, Hilary H. T1 - John Birks BT - pioneer in quantitative palaeoecology T2 - The Holocene N2 - We describe the career of John Birks as a pioneering scientist who has, over a career spanning five decades, transformed palaeoecology from a largely descriptive to a rigorous quantitative science relevant to contemporary questions in ecology and environmental change. We review his influence on students and colleagues not only at Cambridge and Bergen Universities, his places of primary employment, but also on individuals and research groups in Europe and North America. We also introduce the collection of papers that we have assembled in his honour. The papers are written by his former students and close colleagues and span many of the areas of palaeoecology to which John himself has made major contributions. These include the relationship between ecology and palaeoecology, late-glacial and Holocene palaeoecology, ecological succession, climate change and vegetation history, the role of palaeoecological techniques in reconstructing and understanding the impact of human activity on terrestrial and freshwater ecosystems and numerical analysis of multivariate palaeoecological data. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 420 KW - climate change KW - ecosystem history KW - Holocene KW - late-glacial KW - numerical data analysis KW - palaeoecology KW - palaeolimnology Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-404544 ER - TY - JOUR A1 - Julier, Adele C. M. A1 - Jardine, Phillip E. A1 - Adu-Bredu, Stephen A1 - Coe, Angela L. A1 - Duah-Gyamfi, Akwasi A1 - Fraser, Wesley T. A1 - Lomax, Barry H. A1 - Malhi, Yadvinder A1 - Moore, Sam A1 - Owusu-Afriyie, Kennedy A1 - Gosling, William D. T1 - The modern pollen-vegetation relationships of a tropical forest-savannah mosaic landscape, Ghana, West Africa JF - Palynology N2 - Transitions between forest and savannah vegetation types in fossil pollen records are often poorly understood due to over-production by taxa such as Poaceae and a lack of modern pollen-vegetation studies. Here, modern pollen assemblages from within a forest-savannah transition in West Africa are presented and compared, their characteristic taxa discussed, and implications for the fossil record considered. Fifteen artificial pollen traps were deployed for 1 year, to collect pollen rain from three vegetation plots within the forest-savannah transition in Ghana. High percentages of Poaceae and Melastomataceae/Combretaceae were recorded in all three plots. Erythrophleum suaveolens characterised the forest plot, Manilkara obovata the transition plot and Terminalia the savannah plot. The results indicate that Poaceae pollen influx rates provide the best representation of the forest-savannah gradient, and that a Poaceae abundance of >40% should be considered as indicative of savannah-type vegetation in the fossil record. KW - pollen KW - transitions KW - Poaceae KW - savannah KW - Ghana KW - palaeoecology KW - Bosumtwi Y1 - 2017 U6 - https://doi.org/10.1080/01916122.2017.1356392 SN - 0191-6122 SN - 1558-9188 VL - 42 IS - 3 SP - 324 EP - 338 PB - Taylor & Francis Group CY - Philadelphia ER - TY - GEN A1 - Epp, Laura Saskia A1 - Kruse, Stefan A1 - Kath, Nadja J. A1 - Stoof-Leichsenring, Kathleen Rosemarie A1 - Tiedemann, Ralph A1 - Pestryakova, Luidmila Agafyevna A1 - Herzschuh, Ulrike T1 - Temporal and spatial patterns of mitochondrial haplotype and species distributions in Siberian larches inferred from ancient environmental DNA and modeling T2 - Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe N2 - Changes in species' distributions are classically projected based on their climate envelopes. For Siberian forests, which have a tremendous significance for vegetation-climate feedbacks, this implies future shifts of each of the forest-forming larch (Larix) species to the north-east. However, in addition to abiotic factors, reliable projections must assess the role of historical biogeography and biotic interactions. Here, we use sedimentary ancient DNA and individual-based modelling to investigate the distribution of larch species and mitochondrial haplotypes through space and time across the treeline ecotone on the southern Taymyr peninsula, which at the same time presents a boundary area of two larch species. We find spatial and temporal patterns, which suggest that forest density is the most influential driver determining the precise distribution of species and mitochondrial haplotypes. This suggests a strong influence of competition on the species' range shifts. These findings imply possible climate change outcomes that are directly opposed to projections based purely on climate envelopes. Investigations of such fine-scale processes of biodiversity change through time are possible using paleoenvironmental DNA, which is available much more readily than visible fossils and can provide information at a level of resolution that is not reached in classical palaeoecology. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1052 KW - ecological genetics KW - ecological modelling KW - palaeoecology KW - plant ecology KW - climate change KW - introgression KW - temperature KW - treeline KW - vegetation KW - mitochondrial haplotypes KW - Siberian larch KW - larch species KW - range shifts KW - vegetation-climate feedbacks KW - ecosystems KW - impacts KW - dynamics Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-468352 SN - 1866-8372 IS - 1052 ER - TY - JOUR A1 - Foster, William J. A1 - Heindel, Katrin A1 - Richoz, Sylvain A1 - Gliwa, Jana A1 - Lehrmann, Daniel J. A1 - Baud, Aymon A1 - Kolar-Jurkovsek, Tea A1 - Aljinovic, Dunja A1 - Jurkovsek, Bogdan A1 - Korn, Dieter A1 - Martindale, Rowan C. A1 - Peckmann, Jörn T1 - Suppressed competitive exclusion enabled the proliferation of Permian/Triassic boundary microbialites JF - The Depositional Record : the open access journal of the International Association of Sedimentologists N2 - During the earliest Triassic microbial mats flourished in the photic zones of marginal seas, generating widespread microbialites. It has been suggested that anoxic conditions in shallow marine environments, linked to the end-Permian mass extinction, limited mat-inhibiting metazoans allowing for this microbialite expansion. The presence of a diverse suite of proxies indicating oxygenated shallow sea-water conditions (metazoan fossils, biomarkers and redox proxies) from microbialite successions have, however, challenged the inference of anoxic conditions. Here, the distribution and faunal composition of Griesbachian microbialites from China, Iran, Turkey, Armenia, Slovenia and Hungary are investigated to determine the factors that allowed microbialite-forming microbial mats to flourish following the end-Permian crisis. The results presented here show that Neotethyan microbial buildups record a unique faunal association due to the presence of keratose sponges, while the Palaeotethyan buildups have a higher proportion of molluscs and the foraminifera Earlandia. The distribution of the faunal components within the microbial fabrics suggests that, except for the keratose sponges and some microconchids, most of the metazoans were transported into the microbial framework via wave currents. The presence of both microbialites and metazoan associations were limited to oxygenated settings, suggesting that a factor other than anoxia resulted in a relaxation of ecological constraints following the mass extinction event. It is inferred that the end-Permian mass extinction event decreased the diversity and abundance of metazoans to the point of significantly reducing competition, allowing photosynthesis-based microbial mats to flourish in shallow water settings and resulting in the formation of widespread microbialites. KW - Competitive exclusion KW - Permian KW - Triassic KW - mass extinction KW - microbialites KW - palaeoecology Y1 - 2019 U6 - https://doi.org/10.1002/dep2.97 SN - 2055-4877 VL - 6 IS - 1 SP - 62 EP - 74 PB - Wiley CY - Hoboken ER - TY - JOUR A1 - Engels, Stefan A1 - Medeiros, Andrew S. A1 - Axford, Yarrow A1 - Brooks, Steve A1 - Heiri, Oliver A1 - Luoto, Tomi P. A1 - Nazarova, Larisa B. A1 - Porinchu, David F. A1 - Quinlan, Roberto A1 - Self, Angela E. T1 - Temperature change as a driver of spatial patterns and long-term trends in chironomid (Insecta: Diptera) diversity JF - Global change biology N2 - Anthropogenic activities have led to a global decline in biodiversity, and monitoring studies indicate that both insect communities and wetland ecosystems are particularly affected. However, there is a need for long-term data (over centennial or millennial timescales) to better understand natural community dynamics and the processes that govern the observed trends. Chironomids (Insecta: Diptera: Chironomidae) are often the most abundant insects in lake ecosystems, sensitive to environmental change, and, because their larval exoskeleton head capsules preserve well in lake sediments, they provide a unique record of insect community dynamics through time. Here, we provide the results of a metadata analysis of chironomid diversity across a range of spatial and temporal scales. First, we analyse spatial trends in chironomid diversity using Northern Hemispheric data sets overall consisting of 837 lakes. Our results indicate that in most of our data sets, summer temperature (T-jul) is strongly associated with spatial trends in modern-day chironomid diversity. We observe a strong increase in chironomid alpha diversity with increasing T-jul in regions with present-day T-jul between 2.5 and 14 degrees C. In some areas with T-jul > 14 degrees C, chironomid diversity stabilizes or declines. Second, we demonstrate that the direction and amplitude of change in alpha diversity in a compilation of subfossil chironomid records spanning the last glacial-interglacial transition (similar to 15,000-11,000 years ago) are similar to those observed in our modern data. A compilation of Holocene records shows that during phases when the amplitude of temperature change was small, site-specific factors had a greater influence on the chironomid fauna obscuring the chironomid diversity-temperature relationship. Our results imply expected overall chironomid diversity increases in colder regions such as the Arctic under sustained global warming, but with complex and not necessarily predictable responses for individual sites. KW - Arctic KW - biodiversity KW - climate warming KW - freshwater ecosystems KW - insects KW - palaeoecology KW - Quaternary Y1 - 2019 U6 - https://doi.org/10.1111/gcb.14862 SN - 1354-1013 SN - 1365-2486 VL - 26 IS - 3 SP - 1155 EP - 1169 PB - Wiley CY - Hoboken ER -