Isopollen maps for 18,000 years B.P. of the offshore of Northwest Africa: Evidence for paleowind circulation

Distribution patterns of the most important pollen types from southern European and northwest African source areas for the 18,000 years B.P. time slice are reconstructed from pollen records of 14 well-dated deep-sea cores located between 37° and 9°N and compared with the modern pollen distribution in this area. It is concluded that the belt with maximum African Easterly Jet transport did not shift latitudinally during the last glacial-interglacial transition but remained at about 20°N. Furthermore, it is substantiated that the trade winds did not shift latitudinally during the last glacial-interglacial transition. This evidence is not compatible with an atmospheric circulation model that assumes a zone of surface westerlies in the northern part of northwest Africa. Trade winds during glacial episodes did, however, intensify, especially from about 36° to 24° N.

Pollen analysis, particle size analysis, end-member modelling and x-ray fluorescence measurements from sediment cores off Cape Ghir, Morocco

Understanding past human-climate-environment interactions is essential for assessing the vulnerability of landscapes and ecosystems to future climate change. This is particularly important in southern Morocco where the current vegetation is impacted by pastoralism, and the region is highly sensitive to climate variability. Here, we present a 2000-year record of vegetation, sedimentation rate, XRF chemical element intensities, and particle size from two decadal-resolved, marine sediment cores, raised from offshore Cape Ghir, southern Morocco. The results show that between 650 and 850 AD the sedimentation rate increased dramatically from 100 cm/1000 years to 300 cm/1000 years, and the Fe/Ca and pollen flux doubled, together indicating higher inputs of terrestrial sediment. Particle size measurements and end-member modelling suggest increased fluvial transport of the sediment. Beginning at 650 AD pollen levels from Cichorioideae species show a sharp rise from 10% to 20%. Pollen from Atemisia and Plantago, also increase from this time. Deciduous oak pollen percentages show a decline, whereas those of evergreen oak barely change. The abrupt increase in terrestrial/fluvial input from 650 to 850 AD occurs, within the age uncertainty, of the arrival of Islam (Islamisation) in Morocco at around 700 AD. Historical evidence suggests Islamisation led to population increase and development of southern Morocco, including expanded pastoralism, deforestation and agriculture. Livestock pressure may have changed the vegetation structure, accounting for the increase in pollen from Cichorioideae, Plantago, and Artemisia, which include many weedy species. Goats in particular may have played a dominant role as agents of erosion, and intense browsing may have led to the decline in deciduous oak; evergreen oak is more likely to survive as it re-sprouts more vigorously after browsing. From 850 AD to present sedimentation rates, Fe/Ca ratios and fluvial discharge remain stable, whereas pollen results suggest continued degradation. Pollen results from the past 150 years suggest expanded cultivation of olives and the native argan tree, and the introduction of Australian eucalyptus trees. The rapidly increasing population in southern Morocco is causing continued pressure to expand pastoralism and agriculture. The history of land degradation presented here suggests that the vegetation in southern Morocco may have been degraded for a longer period than previously thought and may be particularly sensitive to further land use changes. These results should be included in land management strategies for southern Morocco.

Lithology and palynology of profiles from three low mountain ranges in northern Germany

Im Fichtelgebirge, im Harz und in der Rhön wurden die spätglazialen und frühpostglazialen Ablagerungen von vier Mooren in 625-805 m Meereshöhe pollenanalytisch hinsichtlich von Makrofossilien (Samen, Früchte) und stratigraphisch untersucht. 1. Nur im Fichtelgebirge konnte in 625 m Höhe ein vollständiger Spätglazialablauf aufgedeckt werden. Es handelt sich dabei um einen ehemaligen kleinen See südlich Fichtelberg, der wahrscheinlich durch Tieftauen eines begrabenen Firn- oder Schneefeldes entstand. Betula pubescens wurde kontinuierlich vom Ende der Älteren Tundrenzeit bis zum Boreal nachgewiesen. Auf nahe Vorkommen von Kiefern darf man seit IIb (Jüngere Allerödzeit) schließen, sie wurden aber durch die Jüngere Tundrenzeit, während der es noch zu Solifluktionserscheinungen kam, von ihren höher gelegenen Standorten wieder verdrängt. Die allerödzeitlichen Birken- bzw. Birkenkiefernwälder müssen in diesen Höhen noch licht oder parkartig gewesen sein. Verbreitet waren Rasengesellschaften, die hauptsächlich aus Gramineen und Artemisia bestanden. Auch Beutla nana und Pollen von Ephedra cf. distachya wurden nachgewiesen. In der Seelohe (770-780 m) ist nur der Ausklang einer waldarmen Zeit, offensichtlich der Jüngeren Tundrenzeit, erfaßt. Großreste von Bäumen fehlen. 2. Im Oberharz (Radauer Born, 800 m) wurde nur ein kurzes Stück der Jüngeren Tundrenzeit aufgedeckt. Großreste von Bäumen fehlen hier ebenfalls. Aus dem Praeboreal stammt der erst fossile Nachweis von Betuala nana im Oberharz. Die Zwergbirke wächst auf dem Moor noch heute und gilt hier als Eiszeitrelikt. 3. Eine Datierung der spätglazialen Ablagerungen vom Roten Moor in der Rhön ist zur Zeit nur mit Vorbehalt möglich. Zwar wurde hier der Laacher Bimstuff gefunden, er ist jedoch umgelagert und unmittelbar über dem Tuffhorizont befindet sich eine Schichtlücke. Wahrscheinlich zeigt die Bimsstuffschicht aber doch noch den Allerödhorizont an. 4. Während der Jüngeren Tundrenzeit dürfte im Fichtelgebirge die Waldgrenze bei etwas 600 m gelegen haben. Das bedeutet gegenüber der heutigen Waldgrenze eine Erniedrigung um rund 700 m. Am Schluß der Älteren Tundrenzeit lag die Waldgrenze wahrscheinlich wie in der Allerödzeit höher als 600-650 m, aber unter 800 m. 5. Pollenkörner der Ericalen sind in den Ablagerungen aus dem Harz wesentlich häufiger als in den anderene Gebieten. Häufungen von Ericalen-pollen sind besonders für Spätglazialablagerungen solcher Gebiete charakteristisch, die heute im subozeanischen oder ozeanischen Klimabereich liegen (Niederlande, Irland). 6. Während sich die Bodengegensätze in der heutigen Vegetation der drei Untersuchungsgebiete sehr deutlich bemerkbar machen, wurden keine nennenswerten Unterschiede im spätglazialen Pollenniederschlag der drei Mittelgebirge gefunden. Vermutlich erfolgte die Auswaschung der Nährstoffe aus den an sich nährstoffkräftigen Granitverwitterungsböden während der Späteiszeit nicht so rasch, wie es heute der Fall ist. Die Niederschlagsmengen dürften geringer und das Klima weniger humid gewesen sein. 7. In der Liste der spätglazialen Pflanzen überwiegen die Arten mit borealzirkumpolarer Verbreitung. Arktisch-alpine Arten treten zurück. Kontinentale und subatlantische bzw. subozeanische Arten sind etwa gleich stark vertreten.

Palynology on profile Rotmoss at Obergurgl in Austria

Die pollenanalytische Untersuchung des Rotmooses in Verbindung mit C-14 Daten hat ergeben, daß die organogenen Sedimente nachwärmezeitliche Bildungen sind. Ein Gletschervorstoß um 2500 v. Chr. konnte mit Hilfe der C-14 Daten eingegrenzt und mit anderen Fundstellen parallelisiert werden. Weitere pollenanalytisch festgestellte Gletscher und auch Waldgrenzschwankungen konnten festgestellt, müssen aber noch genau datiert und parallelisiert werden.

Pollen records of profile Krumbach from southern Germany

Some years ago a fossil lake basin was found in the northeastern part of the former Rhine-pied- mont-glacier, situated between the endmoraine system ofthe elassical Riß- andWürm glacia- tions, respectively. The lacustrine sediments contain the pollenflora ofthe Eemian interglacial. They are intensively thrusted. These sediments are eovered by a loam-layer, rieh in elasts. The thickness of this loam-layer varies between at least 170 and 400 cm. It consists in its major part of loess-loam and solifluction material. Yet just on top of the lake sediments mentioned an in- tensively compressed loam, characterized by quarzgrains with all features of glacially pressed material, together with striated elasts is met with. It strongly resembles atil!. Ifthis is true, the stratigraphie division ofthe last glaciation strongly deviates from the hitherto accepted scheme, incorporating an early glacier advance, long before the elassical young-endmoraine systems of the Würm glaciation were formed.

Biostratigraphical investigations of Lago d'Averno, near Naples

Remains of diatoms, molluscs, ostracods, foraminifera and pollen exines preserved in the sediments of Lago d'Averno, a volcanic lake in the Phlegrean Fields west of Naples, allowed us to reconstruct the changes in the ecological conditions of the lake and of the vegetation around it for the period from 800 BC to 800 AD. Lago d'Averno was at first a freshwater lake, temporarily influenced by volcanic springs. Salinity increased slowly during Greek times as a result of subsidence of the surrounding land. Saline conditions developed only after the lake was connected with the sea by a canal, when Portus Julius was built in 37 BC. The first post-Roman period of uplift ended with a short freshwater phase during the 7th century after Christ. Deciduous oakwoods around the lake was transformed into a forest of evergreen oaks in Greek times and thrived there - apparently almost uninfluenced by man - until it was felled, when the Avernus was incorporated into the new Roman harbour in 37 BC, to construct a shipyard and other military buildings there. Land-use was never more intense than during Roman times and weakest in Greek and Early Roman times, when the Avernus was considered a holy place, the entrance to the underworld.

Composition of the argillite sequence, continental slope of the Sea of Japan

The argillite sequence located at the base of the sedimentary cover on the continental slope of the Sea of Japan was studied by petrographic, palynological, and X-ray diffraction methods. Two spores-pollen complexes were distinguished in it: the Late Oligocene reflecting cooling and the Early Miocene corresponding to initiated warming. Data obtained indicate that the sequence is composed of terrigenous silty-clayey sediments that accumulated in shallow coastal-marine settings. The global sea-level rise at the Early-Middle Miocene transition, combined with regional tectonic processes, determined basin's deepening, owing to which the argillite sequence was overlain by a thick layer of Middle Miocene diatomaceous-clayey sediments. Due to tectonic movement along existing faults in the terminal Late Miocene, the argillite sequence occurring initially at depths of at least 400-500 m was locally exhumed to the basin bottom.

Palynological records of sediments from the Odderade type locality, north Germany

Reinvestigation of the Odderade Interstadial in its type locality led to an augmentation of the flora list and correction of some misinterpretations (e.g. Omorica, Frangula). The Eemian, stadials FW 1 and 3, and the interstadials Amersfoort/Broerup and Odderade have been manifested by pollen analyses. FW 1 and FW 3 are probably not completely free from forested areas. The new pollen diagrams considered with older data from Odderade, and in comparison with other regions in Central Europe, fit essentially with the classification and development of Vegetation during the Early Weichselian in Oerel by Behre & Lade (1986).

Pollen record and dating of a sediment profile from Lake Voulkaria, Greece

A palynological investigation of a Holocene profile from Lake Voulkaria, western Greece, was carried out as a contribution to the environmental history of the coastal area of northwestern Acarnania and the Classical city of Palairos. It shows that deciduous oaks dominated the natural vegetation of the area throughout the Holocene. Until ca. 7000 B.C. Pistacia occurred abundantly, while other evergreen woody taxa were rare. At ca. 6300 B.C. an expansion of Carpinus orientalis/Ostrya can be observed. Around ca. 5300 B.C. spreading of Erica indicates a change to a drier climate and/or first human impact. Since ca. 3500 B.C. an increase of evergreen shrubs now clearly indicates land-use. The foundation of the Classical city of Palairos led to a temporary expansion of Phillyrea maquis. Within this period, molluscs of brackish water indicate the use of the lake as a harbour after the construction of a connection to the sea. The deciduous Quercus woodland recovered when human impact decreased in the area, and lasted until modern times.

Lithology and pollen record of 4 profiles from the Bavaria, southern Germany

Palynological investigations of sediments from northern Bavaria (Rhön, Grabfeld, Lange Berge) reveal the Late Glacial and Postglacial history of the regional vegetation. The older sedirnents were found in the Rhön (Schwarzes Moor) and date back into the Bölling Period. At the end of that period pine spread into the Grabfeld. In both areas Lacher Tuff has been found. A radiocarbon date of 10,300 BP was found for the Late Glacial - Postglacial transition and one of 9300 BP for the Preboreal - Boreal transition. Hazel reached its highest values in the Rhön around 7,400 BP. During the Atlanticum a deciduous mixed oak forest covered the Rhön and Grabfeld regions. Beech dominated since the Subatlanticum. In the Lange Berge region, however, a mixed forest with Fagus, Picea, Pinus and Abies developed. In the Rhön first anthropogenic influence was found during the Latene Period. The boundary between zone IX and X has been dated at 820 A.D., and the start of extensive forest clearances at 1000 A. D. A culmination of landuse was found for the Medieval Period. At the end of that period however the Rhön was deserted. New forest clearances started around 1500 A.D., but were interrupted by the 'Thirty Years War'. Afterwards the Rhön got its present appearance.