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.

Late Holocene pollen and organic walled dinoflagellate cysts analyses of sedimet cores from the Java Sea

The pollen, spore and organic walled dinoflagelletas cyst associations of two marine sediment cores from the Java Sea off the mouths of Jelai River (South Kalimantan) and Solo River (East Java) reflect environment and vegetation changes during the last ca 3500 years in the region. A decline in primary forest taxa (e.g. Agathis, Allophylus, Dacrycarpus, Dacrydium, Dipterocarpaceae, Phyllocladus, and Podocarpus) suggest that the major change in vegetation is caused by the forest canopy opening that can be related to human activity. The successively increase of pollen of pioneer canopy and herb taxa (e.g. Acalypha, Ficus, Macaranga/Mallotus, Trema, Pandanus) indicate the development of a secondary vegetation. In Java these changes started much earlier (ca at 2950 cal yr BP) then in Kalimantan (ca at 910 cal yr BP) and seem to be more severe. Changes in the marine realm, reflected by the dinoflagellate cyst association correspond to changes in vegetation on land. They reflect a gradual change from relatively well ventilated to more hypoxic bottom/pore water conditions in a more eutrophic environment. Near the coast of Java, the shift of the water trophic status took place between ca 820 and 500 cal yrs BP, while near the coast of Kalimantan it occurred as late as at the beginning of the 20th century. We observe an increasing amount of the cyst of Polykrikos schwarzii, cyst of P. kofoidii, Lingulodinium machaerophorum, Nematosphaeropsis labyrinthus and Selenopemphix nephroides at times of secondary vegetation development on land, suggesting that these species react strongly on human induced changes in the marine environment, probably related to increased pollution and eutrophication.

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.

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.

Pollen analysis of modern mangrove systems

Three sediment cores from the Bragança Peninsula located in the coastal region in the north-eastern portion of Pará State have been studied by pollen analysis to reconstruct Holocene environmental changes and dynamics of the mangrove ecosystem. The cores were taken from an Avicennia forest (Bosque de Avicennia (BDA)), a salt marsh area (Campo Salgado (CS)) and a Rhizophora dominated area (Furo do Chato). Pollen traps were installed in five different areas of the peninsula to study modern pollen deposition. Nine accelerator mass spectrometry radiocarbon dates provide time control and show that sediment deposits accumulated relatively undisturbed. Mangrove vegetation started to develop at different times at the three sites: at 5120 14C yr BP at the CS site, at 2170 14C yr BP at the BDA site and at 1440 14C yr BP at the FDC site. Since mid Holocene times, the mangroves covered even the most elevated area on the peninsula, which is today a salt marsh, suggesting somewhat higher relative sea-levels. The pollen concentration in relatively undisturbed deposits seems to be an indicator for the frequency of inundation. The tidal inundation frequency decreased, probably related to lower sea-levels, during the late Holocene around 1770 14C yr BP at BDA, around 910 14C yr BP at FDC and around 750 14C yr BP at CS. The change from a mangrove ecosystem to a salt marsh on the higher elevation, around 420 14C yr BP is probably natural and not due to an anthropogenic impact. Modern pollen rain from different mangrove types show different ratios between Rhizophora and Avicennia pollen, which can be used to reconstruct past composition of the mangrove. In spite of bioturbation and especially tidal inundation, which change the local pollen deposition within the mangrove zone, past mangrove dynamics can be reconstructed. The pollen record for BDA indicates a mixed Rhizophora/Avicennia mangrove vegetation between 2170 and 1770 14C yr BP. Later Rhizophora trees became more frequent and since ca. 200 14C yr BP Avicennia dominated in the forest.