Pollen from Lake Sedmo Rilsko reveals southeast European postglacial vegetation in the highest mountain area of the Balkans

A lacustrine sequence from Lake Sedmo Rilsko (altitude 2095 m) in the northwest of Rila Mountain, Bulgaria, was analysed on the basis of 84 pollen spectra and three ¹⁴C accelerator mass spectrometry dates. The lower part of the sequence (413–530 cm) corresponds to the Late-glacial. Three phases, two stadial and one interstadial, are characterized by the dominance of mountain–steppe herb vegetation composed of Artemisia , Chenopodiaceae and Poaceae, with single trees of Pinus and shrub land of Juniperus and Ephedra . The identification of pollen grains of Abies , Quercus robur -type, Corylus , Acer , Fagus and other mesophilous trees suggests that they survived the harsh Late-glacial conditions in refuges below an altitude of 1000 m, where moisture was sufficient for their growth. In the early Holocene period, Betula forests at high altitudes and, below them, closed deciduous forests with Quercus , Tilia , Ulmus and Corylus , occurred from 11800 until approx. 6700 cal. BP. The formation of the coniferous belt dominated by Pinus sylvestris , Pinus peuce and Abies alba lasted from between 6700 and 5000 cal. BP. The forest dynamics in the Subboreal and the Subatlantic ended with the invasion of Fagus sylvatica and Picea abies after approx. 4500 and 3300 cal. BP, respectively. Indications of anthropogenic activities, expansion of agriculture in the lowland foothills, and livestock grazing in the mountain meadows and pastures, are clearly evident from the pollen diagram from 2400 cal. BP onwards.     

Vegetation in the mountains of northwest Iberia during the last glacial-interglacial transition

A new core taken from a site in the Sierra de Courel range of mountains in the northwest Iberian peninsula, Spain, enables a palaeoenvironmental reconstruction to be made of the biological events resulting from climatic changes and human activities during the last 17,000 years in the area. The sequence begins with a phase characterised by the dominance of Gramineae (Poaceae) and Pinus. A markedly arid period with prevalence of Artemisia pollen occurred between 17,5000 and 15,500 uncal. B.P. Subsequently, a succession of woodlands with Betula, Pinus and other mesophilous and thermophilous trees was recognised during the period 15,500-13,500 uncal. B.P. Between 13,500 and 10,300 uncal. B.P. herbaceous vegetation formations indicating moister conditions dominated the pollen record, although a maximum of Gramineae has been dated during the period 11,300-10,300 uncal. B.P. Comparison with other pollen data from neighbouring mountains allows an interpretation of the vegetation changes during the glacial/interglacial transition in the mountains of northwest Iberia. The Holocene pollen record from the site does not differ markedly from other records in the area, tree expansion occurring before 10,000 uncal. B.P. and high values of deciduous Quercus mixed with other trees and shrubs persisting until 3500 uncal. B.P., when increased human activities are shown by a fall of the tree pollen percentages. Received July 7, 1999 / Accepted May 22, 2000     

The identification of wingless Betula fruits in Weichselian sediments in the Gross Todtshorn borehole (Lower Saxony, Germany) – the occurrence of Betula humilis Schrank.

Betula fruits lacking their wings were recovered from the Gross Todtshorn borehole, Germany, covering the late Eemian interglacial, the Early Weichselian, and the Weichselian pleniglacial. In order to identify them, a data-set of seven size and shape variables was made from modern fruits of B. pubescens, B. pendula, B. nana, and B. humilis. These measurements were summarised by principal components analysis (PCA). The 140 measured fossil fruit-bodies were positioned passively on the PCA plot and identified by comparison with the dimensional envelopes of the modern species. Tree birches (B. pendula, B. pubescens) occurred in the Eemian and Early Weichselian interstadials, but not thereafter.B. nana was widespread during the intervening stadials and the Oerel interstadial. B. humilis occurred throughout the sequence, coexisting with tree birches in the Early Weichselian and with B. nana in the stadials. It usually grew on mire surfaces, in contrast to B. nana which mainly grew on mineral substrates. However, B. nana grew on peat with B. humilis in the pleniglacial Oerel interstadial, suggesting a more continental climate with cold winters. A modern analogue could be near the Ural mountains. B. humilis is presently rare in central Europe, but during the Weichselian it was well established in northern Germany. The PCA has enabled specific determination of the wingless Betula fruits, leading to vegetational and climatic reconstructions and contributing to the previously poorly known historical biogeography of Betula humilis. Received June 14, 2000 / Accepted January 2, 2001     

Sclerophyllous vegetation dynamics in the north of the Iberian peninsula during the last 16,000 years

We used pollen analysis to evaluate the dynamics of sclerophyllous arboreal taxa during the last 16,000 years. Quercus ilex type pollen and, to a lesser degree, other sclerophyllous elements (e.g. Olea and Phillyrea ) have been documented during the Late-glacial in the majority of the sequences obtained in continental territories in the north of the Iberian peninsula, as well as in the eastern coastal/sub-coastal area in the Cantabric region. During the Late-glacial and the Holocene, sclerophyllous elements became widespread in many areas of the north Iberian peninsula (the Sil, Duero and Ebro depressions and the southernmost slopes of adjacent mountains), with the smallest pollinic representation of these taxa being for the most septentrional areas (coastal/sub-coastal territories and the northermost slopes of the Cantabrian-Atlantic Mountains). During these periods, there is no indication of the presence of Quercus ilex pollen in the northwestern territories, which would explain the absence of this species in the present-day landscape. Despite the widespread distribution that sclerophyllous elements have maintained during the last 16,000 years, they have never attained a predominant role in the landscape, having a smaller representation, both during hotter and colder phases, than deciduous forests, pine forests and mixed forests.     

Late Quaternary vegetation, fire and climate dynamics of Serra do Araçatuba in the Atlantic coastal mountains of Paraná State, southern Brazil

Late Quaternary vegetation, fire and climate dynamics were studied by pollen and charcoal analysis on a sediment core from near the summit of the Serra do Araçatuba at 1500 m elevation, part of the Serra do Mar coastal mountains of Paraná State, southern Brazil. Three radiocarbon dates indicate that clay and peat were deposited in a shallow basin during the last 14,880 b.p. Accumulation was probably continuous, but sedimentary gaps during the dry mid Holocene cannot be excluded. During late-glacial times the upper coastal mountain were covered with grassland, reflecting relatively dry and cold climatic conditions. Large areas of natural grasslands remained in the upper mountain region during the Holocene. Only after 2000 b.p. did Araucaria forest trees, specially Ilex, some Atlantic forest trees as well as the pioneer Myrsine move to higher elevations, reflecting markedly wetter climatic conditions. This expansion stopped and the forest areas were reduced significantly by human activities during about the last 200–300 years. The modern grassland vegetation of the uppermost mountains may reflect the natural setting, but may also partly result from post-Columbian human activities. Fires were rare during the late Pleistocene and even less frequent during the early and mid Holocene. During the wettest recorded period of the late Holocene fires increased markedly and are therefore most probably of anthropogenic origin.     

Reconstruction of the Allerød vegetation of the Neuwied Basin, western Germany, and its surroundings at 12,900 cal b.p.

During the late-glacial eruption of the Laacher See volcano 12,900 b.p. the whole area of the Neuwied Basin, middle Rhine region, was covered by several metres of the Laacher See Tephra (LST) damaging but also partly conserving the former vegetation. This gave the unique opportunity to study plant remains in situ and to estimate the spatial biodiversity of plant taxa within the area investigated at the end of the last glacial as if in a snapshot of 12,900 years ago. Different kinds of plant material can be found because of different preservation conditions namely imprints, charcoal and waterlogged remains. Investigations of this material from several places within the Neuwied Basin and the Brohl valley north of it allowed the reconstruction of the former vegetation at different scales from local to regional. This resulted in a large scale draft of a vegetation map of the studied area also based on the distribution and the stage of soil development at that time. As to whether thermophilous trees were already present is discussed but largely rejected. Electronic Supplementary Material Supplementary material is available for this article at     

Late Pleistocene small mammals from the Wannenköpfe volcanoes (Neuwied Basin, western Germany) with remarks on the stratigraphic range of Arvicola terrestris

Redeposited loess sediments from a Pleistocene crater filling in the Neuwied Basin (western Germany) yielded a small mammal fauna mainly composed of arvicoline rodents. The occurrence of rare faunal elements such as Sorex minutissimus, Sicista subtilis, and a species of Microtus (Terricola) is remarkable. Based on the evolutionary level of Arvicola terrestris, the biostratigraphic age of the fossiliferous horizon is transitional between late Eemian and early Weichselian. This conclusion is partly supported by the generalized ecological requirements of a few dominant rodent species. The fauna contributes to the knowledge of this time period, which is poorly documented in western Germany. A new character of the m1 is proposed for the discrimination of Sicista betulina and S. subtilis. To avoid further confusion in the specific assignment of transitional Arvicola specimens from the late Middle Pleistocene to early Late Pleistocene, we propose the formal taxonomic boundary between chronospecies A. mosbachensis and A. terrestris to be shifted from SDQ value 100 to SDQ value 120.     

Late-glacial and Holocene climate dynamics at the steppe/forest ecotone in southernmost Patagonia, Argentina: the pollen record from a fen near Brazo Sur, Lago Argentino

We present a pollen record from a fen at the eastern shore of Brazo Sur south of Lago Argentino, Argentina (core BRS 1/06, 50°34′54″S, 72°54′52″W, 198 m a.s.l.). The coring site is located in the transition zone from humid grass steppe to Andean Nothofagus forest. With the exception of a mid-Holocene sand layer, the record covers the interval between 13,350 and 1,700 cal b.p., indicating that there could have been no recurrence of Late-glacial conditions in Brazo Sur, as has been suggested in the literature as having been contemporary with the Younger Dryas interval in the northern hemisphere. The Late-glacial and early Holocene periods at Brazo Sur are characterized by fluctuations between humid grass-dominated steppe associations and drier ones dominated by Asteraceae and Ericaceae. At the start of the Holocene, the pollen influx increased. Nothofagus dominance began by 7,700 cal b.p. probably due to increasing moisture. Present-day closed Nothofagus forest developed around 2,500 cal b.p., related to a further increase in moisture.     

Isozyme evidence for the parentage and multiple origins ofPotamogeton ×suecicus (P. pectinatus ×P. filiformis,Potamogetonaceae)

Evidence from isozyme analyses indicates thatPotamogeton ×suecicus is the hybrid betweenP. pectinatus andP. filiformis. The hybrid appears to have arisen on several occasions. The isozyme profiles of this hybrid from the Rivers Wharfe and Ure in Yorkshire, south of the present limit of distribution ofP. filiformis, suggest that each population is a single clone; these clones may be relics from the Weichselian glacial period. Populations of the putative hybrid from the Rivers Tweed and Till are notP. ×suecicus but probably haveP. vaginatus andP. pectinatus as parents. If so, this is a remarkable example of a pondweed hybrid persisting vegetatively in an area outside the distributional range of one of its parents.