Modern pollen rain and fungal spore assemblages from pasture woodlands around Lake Saint-Point (France)

Modern analogs are commonly used to investigate the relationships between modern pollen rain and the surrounding present vegetation and to improve our interpretation of fossil data. We collected modern pollen and spore rain in 18 more or less grazed and/or forested sites around Lake Saint-Point (Jura Mountains, France). Multivariate numerical techniques were applied to understand how modern pollen and non-pollen palynomorphs (NPP) taxa, collected in moss and dung samples, record local vegetation in the surroundings, and to identify indicators of tree cover or grazing. We show a strong relationship between current local herbaceous vegetation and pollen but underline the limits of past vegetation reconstructions based on AP/NAP ratio. In moss samples, we identified Picea, Abies, Fagus and Coollus pollen as well as Trichocladium, Kretschmaria deusta and Cirrenalia as indicators of tree cover. Spores of Sporormiella and some undetermined palynomorphs such as new NPP LCE-13 were positively correlated with openness while LCE-23 and LCE-32 could represent grazing indicators and/or coprophilous types. As compared to moss samples, dung samples contained much more pollen grains from Trifolium repens-type, Trifolium pratense-type, Plantago lanceolata-type and Plantago major/media-type taxa (grassland species eaten by cattle) and spores from coprophilous fungi. (C) 2012 Elsevier B.V. All rights reserved

Holocene landscape evolution, palaeoclimate and human impact in the Fotsch Valley, Stubai Alps, Austria: Interrogating biomarkers, stable isotopes, macrofossils and palynological indicators from a subalpine mire archive

Peatlands are receiving increasing attention in palaeoenvironmental research and represent very useful terrestrial archives for reconstructing vegetation, climate and human history. Previous palaeoenvironmental studies in the Fotsch Valley, Stubai Alps, Austria, focused on geoarchaeological investigations on the Ullafelsen representing a very important prehistorical encampment site used by Mesolithic hunter-gatherers (10.9–9.5 cal. kyr BP). In order to contribute to a better understanding of the landscape evolution of the Fotsch Valley, we here studied the close-by subalpine ‘Potsdamer Hütte Mire’ by applying radiocarbon dating as well as elemental, biomarker, compound-specific stable isotope, palynological and macrofossil analyses on bulk peat samples. The calculated age-depth model using R Bacon indicates the beginning of peat formation during the Early Holocene and shows a strongly reduced peat accumulation rate (PAR) from 170 to 121 cm depth (8.5–2.1 cal. kyr BP) and/or a striking hiatus. Results of leaf wax-derived n-alkane biomarkers as well as macrofossils and palynological indicators reflect the local presence of coniferous trees and the synchronous expansion of deciduous trees during the Early Holocene. The above-mentioned strongly reduced PAR and/or hiatus coincides with the Neolithic, the Bronze and the Iron Age, and goes hand in hand with strong changes in vegetation and an increase of micro-charcoal and black carbon. Despite age uncertainties, these changes can be explained with strongly increasing human and livestock activities in form of deforestation, domestic fires and the beginning of Alpine pastoralism. The latter is confirmed by the finding of pasture and cultural indicator pollen (Cerealia-type, Rumex, Plantago lanceolata, Poaceae) occurring since the Middle to Late Bronze Age. The oxygen isotope composition of sugar biomarkers (δ18Osugars) likely reflects the dry versus humid climatic variability associated with the Holocene climatic optimum during the Mesolithic, the Roman Age, the Late Antique Little Ice Age, the Middle Ages and the Little Ice Age

10.000 years of climate and settlement dynamics in the Sivretta mountain massif between Paznaun valley (Austria) and the Lower Engadin (Switzerland)

Um die Mechanismen des heutigen Klimawandels zu verstehen und zukünftige Klima-Szenarien zu simulieren, braucht es ein detailliertes Wissen über vergangene Klimaänderungen. Das holozäne Klima und die prähistorische, anthropogene Nutzung der Landschaft hatten einen großen Einfluss auf die vergangene Vegetationszusammensetzung und -entwicklung und führten schlussendlich zur heutigen Kulturlandschaft Europas. Hochalpine Ökosysteme wie in den Alpen Europas sind deshalb ein ideales Forschungsfeld. Mit den Methoden der Palynologie lassen sich vergangene Floren- und Vegetationsveränderungen rekonstruieren, und so die möglichen Ursachen eruieren. In Kombination mit archäologischen Ergebnissen lässt sich der Einfluss des Menschen und dessen Haustiere an Hand von palynologischen Resultaten quantifizieren. In der vorliegenden Arbeit wurden die Standardmethoden der Palynologie zusammen mit der Analyse mikroskopischer Holzkohle und von Extrafossilien (engl. non-pollen palynomorphs) an vier Torf-Stratigraphien an Hand eines Nord-Süd-Transektes durch das Silvretta-Gebirgsmassiv und dem Unterengandin in der Schweiz angewendet. Seit 2007 wurden in diesem Gebiet mehr als 200 archäologische Fundstellen oberhalb von 1800 m ü. M. gefunden und untersucht. Die erste menschliche Präsenz konnte dabei für die Mittelsteinzeit für die Zeit vor ca. 11500 Jahren nachgewiesen werden. Die in den vier untersuchten Mooren erarbeiteten palynologischen Resultate decken den Zeitraum der letzten 10450 Jahre ab, und wurden in der Form von vier Artikeln in wissenschaftlichen Zeitschriften publiziert bzw. eingereicht. Die Ergebnisse wurden zudem mit den archäologischen Erkenntnissen aus der Region, sowie mit Proxy-Daten aus den Gebieten der Makrofossilanalyse, der Dendrochronologie, Pedologie sowie der Röntgenfluoreszenzanalyse verglichen. Alle diese Methoden tragen zur Rekonstruktion der holozänen Waldgrenze in den Silvretta-Alpenbei, wie zum Beispiel im Hinblick auf die Herabsetzung der Waldgrenze von 2300 auf 2150 m ü. M. vor ca. 4200 Jahren. Weitere wichtige, und klimabedingte Wechsel in der Vegetationszusammensetzung wurden für die globale Kältephase vor 8200 Jahre, für die v.a. im Mittelmeerraum nachweisbare, trocken-kalte Periode vor ca. 4200 Jahren, und für die kalt-feuchte Zeit um vor ca. 2800 Jahren nachgewiesen, letztere wohl bewirkt durch eine Reduktion der solaren Aktivität. Erste weidewirtschaftlichen Aktivitäten datieren möglicherweise zurück in die Jungsteinzeit (vor 6200 bis 4900 Jahren), wurden jedoch ab der Frühbronzezeit (vor 4200 bis 3800 Jahren)stark intensiviert. Mit größter Wahrscheinlichkeit war die prähistorische Landwirtschaft im Unterengandin sowie die Weidewirtschaft in den Höhenlagen des Silvretta-Gebirgsmassivsauf die Anwendung von Feuer zur Öffnung der dichten Wälder angewiesen. Eine weiter Intensivierung der Weidewirtschaft ist während der Eisenzeit um ca. 600 v. Chr. festzustellen. Während der Römerzeit und der Frühbronzezeit war die Silvretta-Gegend hingegen weniger stark beweidet, dies möglicherweise im Zusammenhang mit der Klimaverschlechterung des sogenannten „Bond-Event-1“. Andererseits hat die mittelalterliche Wärmezeit die Etablierung der heutigen neuzeitlichen Kulturlandschaft und der heutigen Weidewirtschaft erlaubt, selbst wenn die Kaltphase der sogenannten Kleinen Eiszeit (von ca. 13501850 n. Chr.) negative Effekte auf den Kulturpflanzenanbau gehabt haben dürfte.Understanding the current mechanisms of climatic change along with the simulation of future climates depend on the accurate knowledge of past climatic events. The Holocene climate and anthropogenic land-use during prehistory had a major impact on vegetation composition and development and ultimately shaped the current cultural landscape in Europe. Given their high sensitivity to disturbances, high altitude ecosystems such as the European Alps offer an essential research area to emphasise this point. Palynology allows one to reconstruct changes of past Holocene flora and vegetation and to identify the possible origins of such alterations. Moreover, in combination with archaeological evidence, palynology also permits one to gauge the impact of the human population and of their livestock. Standard palynological methods including micro-charcoal and non-pollen palynomorph analyses were applied to four peat stratigraphies taken along a North-South transect through the Silvretta Massif and the Lower Engadine Valley, Switzerland. Since 2007, more than 200 archaeological sites above 1,800 m a.s.l. were detected and investigated in this area. The first archaeological evidence of human presence dates back to the Mesolithic Period (ca. 11500 cal. BP). The palynological data from the four peat bogs investigated together cover a time span that dates back to 10450 years ago, and were published or submitted in four scientific journals. The results were also compared with the archaeological evidence known in the area, as well as with proxy data from macro-remains, denchrochronology, pedology and X-ray fluorescence analyses. These methods all help to reconstruct the timberline fluctuations in the Silvretta-Alps during the Holocene, especially the treeline lowering around 4200 cal. BP from about 2300 to 2150 m a.s.l. Other major shifts in vegetation composition due to climatic oscillations were identified, such as during the global 8.2 ka cold event, during the 4.2 ka dry-cool period characterizing the Mediterranean area, and during the 2.8 ka cold-humid phase induced by a reduction in solar radiation. First agro-pastoral activities in the area might date back to the Neolithic Period (62004900 cal. BP), but they were clearly intensified during the Early Bronze Age (42003800 cal. BP). The development of prehistorical agricultural field systems in the Lower Engadine Valley and of the Alpine pastoral areas in the Silvretta Massif most probably involved slash-and-burn techniques in order to open the dense forest vegetation. A second intensification of agro-pastoral practises occurred around 2550 cal. BP (600 BC) during the Iron Age. During the Roman Period and the Early Middle Ages the Alpine land of the Silvretta area seem to have been used less in terms of pasture, possibly due to the Bond Event 1 cold phase. On the other hand, the Medieval Warm Period (also known as Medieval Climate Anomaly) permitted the establishment of the current cultural and pastoral landscape, despite the subsequent deleterious effects of the Little Ice Age cooling (ca. AD 1350-1850) on the cultivation possibilities.by Benjamin DietreAbweichender Titel laut Übersetzung der Verfasserin/des VerfassersEnth. u.a. 4 Veröff. d. Verf. aus den Jahren 2014 - 2015 . - Zsfassung in dt. SpracheInnsbruck, Univ., Diss., 2015OeBB(VLID)46375

Modern pollen rain and fungal spore assemblages from pasture woodlands at Lake Saint-Point (France)

International audienceModern analogs are commonly used to investigate the relationships between modern pollen rain and the surrounding present vegetation and to improve our interpretation of fossil data. We collectedmodern pollen and spore rain in 18more or less grazed and/or forested sites around Lake Saint-Point (JuraMountains, France). Multivariate numerical techniques were applied to understand how modern pollen and non-pollen palynomorphs (NPP) taxa, collected in moss and dung samples, record local vegetation in the surroundings, and to identify indicators of tree cover or grazing.We showa strong relationship between current local herbaceous vegetation and pollen but underline the limits of past vegetation reconstructions based on AP/NAP ratio. In moss samples, we identified Picea, Abies, Fagus and Corylus pollen as well as Trichocladium, Kretschmaria deusta and Cirrenalia as indicators of tree cover. Spores of Sporormiella and some undetermined palynomorphs such as new NPP LCE-13 were positively correlated with openness while LCE-23 and LCE-32 could represent grazing indicators and/or coprophilous types. As compared to moss samples, dung samples contained much more pollen grains from Trifolium repens-type, Trifolium pratense-type, Plantago lanceolata-type and Plantago major/media-type taxa (grassland species eaten by cattle) and spores from coprophilous fungi

Palaeoecological evidence for Mesolithic to Medieval climatic change and anthropogenic impact on the Alpine flora and vegetation of the Silvretta Massif (Switzerland/Austria)

In a high altitude region such as the Silvretta Alps (Switzerland/Austria), past and extant settlement activities are known to have had large influences on the alpine flora and vegetation. The Silvretta Massif harbors more than 230 archaeological sites above 2000 m a.s.l. on a total area of 550 km2, from the Mesolithic period to Modern Times, but received little attention in these matters up to recently. The Fimba Valley within the Silvretta area e with 47 known archaeological sites (6 prehistoric, 21 from the Medieval and/or Modern Times, 20 undated) located over an area of 62 km2 e provides evidence of a broad range of former human presence, as well as peat records allowing the reconstruction of Holocene climatic change and anthropogenic impact on past vegetation. Here, we present a high resolution, multiproxy study (including pollen, cryptogam spores, and non-pollen palynomorphs) on a 177-cm-long radiocarbon dated peat core from the Las Gondas Bog in the Fimba Valley (2363 m a.s.l.). Palynological evidence adds and confirms previous dendrochronological results, revealing extensive high Pinus cembra (Arolla pine) stands around the bog at 10,400 cal BP and between ca. 8600e6700 cal. BP, more than 300 altitudinal meters above today’s timberline, and belonging therefore to the highest population known for Central Europe. In addition, our palaeoecological results correlate well with the archaeologically known human impact during the Neolithic, Iron Age and Medieval periods. The exploitation of alpine landscape resources (cultivation of cereals in the valleys) and livestock grazing (in the subalpine and alpine areas) has therefore a long tradition going back at least for 6200 years in the Silvretta region

L’histoire de la végétation depuis la fin du tardiglaciaire et l’évolution de l’emprise humaine à partir du milieu de l’holocène dans le Massif Central oriental (France)

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Late-Glacial and Early Holocene environmental changes affecting the shallow lake basin of La Narce du Béage (Ardèche, Massif Central, France)

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