Pollen and macroremains from four profiles from site Samerberg 1

Pollen and macrofossil analysis of lake sediments revealed the complete development of vegetation from Riss late-glacial to early Würm glacial times at Samerberg (12°12' E, 47°45' N, 600 m a.s.l) on the northern border of the Alps. The pollen bearing sediments overlie three stratigraphic units, at the base a ground-moraine, then a 13 m thick layer of pollen free silt and clay, and then a younger moraine; all the sediments including the pollen bearing sediments, lie below the Würm moraine. The lake, which had developed in an older glacial basin, became extinct, when the ice of the river Inn glacier filled its basin during Würm full-glacial time at the latest. One interglacial, three interstadials, and the interdigitating treeless periods were identified at Samerberg. Whereas the cold periods cannot be distinguished from one another pollenanalytically, the interglacial and the two older interstadials have distinctive characteristics. A shrub phase with Juniperus initiated reforestation and was followed by a pine phase during the interglacial and each of the three interstadials. The further development of the interglacial vegetation proceeded with a phase when deciduous trees (mainly Quercus, oak) and hazel (Corylus) dominated, though spruce (Picea) was present at the same time in the area. A phase with abundant yew (Taxus) led to an apparently long lasting period with dominant spruce and fir (Abies) accompanied by some hornbeam (Carpinus). The vegetational development shows the main characteristics of the Riss/Würm interglacial, though certain differences in the vegetational development in the northern alpine foreland are obvious. These differences may result from the existence of an altitudinal zonation of the vegetation in the vicinity of the site and are the expression of its position at the border of the Alps. A greater age (e.g. the Holsteinian) can be excluded by reason of the vegetational development, and is also not indicated at first sight from the geological and stratigraphical data of the site. Characteristic of the Riss/Würm vegetational development in southern Germany - at least in the region between Lake Starnberg/Samerberg/Salzach - is the conspicuous yew phase. According to absolute pollen counts, yew not only displaced the deciduous species, but also displaced spruce preferentially, thus indicating climatic conditions less favourable for spruce, caused by mild winters (Ilex spreading!) and by short-term low precipitation, indicated by the reduced sedimentation rate. The oldest interstadials is bipartite, as due to the climatic deterioration the early vegetational development, culminating in a spruce phase, had been interrupted by another expansion of pine. A younger spruce-dominated period with fir and perhaps also with hornbeam and beech (Fagus) followed. An identical climatic development has been reported from other European sites with long pollen sequences (see chapter 6.7). However, different tree species are found in the same time intervals in Middle Europe during Early Würm times. Sediments of the last interglacial (Eem or Riss/Würm) have been found in all cases below the sediments of the bipartite interstadial, and in addition one more interstadial occurs in the overlying sediments. This proves that Eem and Riss/Würm of the north-european plain resp. of the alpine foreland are contemporaneous interglacials although this has been questioned by some authors. The climax vegetation of the second interstadial was a spruce forest without fir and without more demanding deciduous tree species. The vegetational development of the third interstadial is recorded fragmentary only. But it has been established that a spruce forest was present. The oldest interstadial must correspond to the danish Brørup interstadial as it is expressed in northern Germany, the second one to the Odderade interstadial. A third Early Würm interstadial, preserved fragmentarily at Samerberg, is known from other sites. The dutch Amersfoort interstadial most likely is the equivalent to the older part of the bipartite danish Brørup interstadial.

(Table 2) Temporal changes in phenological observations between 1978 and 2007, northern Sweden

A 30-year series (1978-2007) of photographic records were analysed to determine changes in lake ice cover, local (low elevation) and montane (high elevation) snow cover and phenological stages of mountain birch (Betula pubescens ssp. czerepanovii) at the Abisko Scientific Research Station, Sweden. In most cases, the photographic-derived data showed no significant difference in phenophase score from manually observed field records from the same period, demonstrating the accuracy and potential of using weekly repeat photography as a quicker, cheaper and more adaptable tool to remotely study phenology in both biological and physical systems. Overall, increases in ambient temperatures coupled with decreases in winter ice and snow cover, and earlier occurrence of birch foliage, signal a reduction in the length of winter, a shift towards earlier springs and an increase in the length of available growing season in the Swedish sub-arctic.

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.