The long history of Cannabis and its cultivation by the Romans in central Italy, shown by pollen records from Lago Albano and Lago di Nemi

The cores from the Albano and Nemi lakes, near Rome, were studied within the European Union funded PALICLAS project and provided high resolution records of the Late-glacial and Holocene. Pollen evidence of increasing human influence on vegetation was recorded in the Holocene parts of both diagrams, and the Cannabis (hemp) curve was one of the major signs. In this paper we present unambiguous pollen evidence from the Cannabaceae records for the cultivation of hemp in central Italy by the Romans. The oldest records of Cannabis and Humulus (hop) date from to the Late-glacial. Hop pollen values rise during the mid Holocene, while hemp pollen becomes more abundant from ca. 3000 cal B.P. onwards. The highest earliest hemp peak (21%) is dated to the 1st century A.D. This ‘Cannabis phase’, with the abrupt rise of hemp pollen soon after the rise of cultivated trees (Castanea, Juglans and Olea) is associated with the increase in cereals and ruderal plants. This unambiguous proof of cultivation by Romans around 2000 B.P. occurs as well as a long lasting pre-Roman presence of hemp in the area, which is natural and possibly also anthropogenic. Subsequent clear episodes of cultivation in the medieval period were found. Received February 4, 2002 / Accepted September 13, 2002 Correspondence to: Anna Maria Mercuri, e-mail: mercuri.annamaria@unimo.it     

Late- and post-glacial vegetation and climate history of the south-western Taymyr Peninsula, central Siberia, as revealed by pollen analysis of a core from Lake Lama

On the Taymyr Peninsula and Severnaya Zemlya Archipelago, Central Siberia, a joint German/Russian multidisciplinary research project focuses on the Late Quaternary history of climate and environment. Within the scope of this project, palynological studies were carried out on a 10.8-m core from Lama Lake, situated in the south-west of the research area. The core, which did not reach the base of the lacustrine sediments, reveals the vegetation and climate history of the last 17 000 years and demonstrates that this area was not glaciated during that time. The Pleistocene/Holocene transition is, as elsewhere in the northern hemisphere, characterized by increased temperatures during the Bølling, Allerød and Preboreal with interruptions during the Older (post-Bølling) and Younger Dryas events. The Holocene climate optimum at Lama Lake probably occurred within the Boreal period, when dense larch forests developed. The Atlantic period was characterized by warm conditions that favoured the establishment of larch-spruce forests, though a climatic deterioration is also recorded. During the Subboreal, spruce fluctuated in importance, on the basis of which it is suggested that there were two cool periods with an intervening warm period. Since 3000 B.P., the climate has become considerably cooler and forests have degenerated. During the last 1000 years, unfavourable climate conditions have resulted in a forest tundra and widespread tundra communities developing in the Lama Lake region.This paper is dedicated to Hans-Jürgen Beug on the occasion of his 65th birthday.     

Late-glacial vegetational ecotones and climatic patterns in Western Norway

The mapping of Weichselian late-glacial interstadial (13-11 ka B.P.) and Younger Dryas stadial (11-10 ka B.P.) pollen percentages for selected taxa demonstrates vegetational and hence climatic differentiation in Western Norway during these times. In the south, early interstadial Salix dominance was replaced by Betula woodland development. During Younger Dryas time, Betula pollen declined to values consistent with a modern vegetational analogue of the vegetation at the upper forest limit. In the inner fjord areas north of Stavanger, the interstadial vegetation contained scattered birch trees, the density depending on local topography and soils. During the Younger Dryas, vegetation resembling the modern mid- and low-alpine vegetation developed. On the outer coast, the interstadial vegetation was probably treeless, and dominated by Salix spp., including S. herbacea, and herbs. The vegetation became even more open during the Younger Dryas, resembling that of the modern mid- and high-alpine zones. The spatial ecotones delimiting the three areas of different vegetation development during both the interstadial and the Younger Dryas can be placed north of Stavanger, separating the southern region, and between the outer coast and inner fjord areas to the north. The Younger Dryas drop in temperature in all areas was up to about 5°C, enough to pass ecotonal thresholds in time in all areas.     

Towards an absolute chronology for the last glacial period in Europe: radiocarbon dates from Oerel,northern Germany

Radiocarbon dates from the terrestrial Weichselian standard profile of Oerel are presented. The end of the Early Weichselian (WE IV, corresponding to isotopic stage 5a) is dated by two independent analyses to around 61 000 years B.P. The two subsequent interstadials, Oerel and Glinde, which have been described from this locality in an earlier publication, are dated to ca. 58 000 - 54 000 B.P. and 51 000- 48 000 B.P., respectively. The dates of both interstadials are in good agreement with the chronology available from the deep sea record. The chronology of the younger part of the Pleni-Weichselian is briefly reviewed.     

Late-glacial fluctuations of timberline in the Black Forest (SW Germany)

Based on pollen diagrams from nine sites at altitudes between 654 and 1280 m a.s.l. the Late-glacial fluctuations of the timberline are reconstructed and interpreted in terms of summer temperature.     

A multi-proxy Late-glacial palaeoenvironmental record from Lake Bled, Slovenia

This study investigates the palaeoecological record (δ¹⁸O, δ¹³C, pollen, plant macrofossils, chironomids and cladocera) at Lake Bled (Slovenia) sedimentary core to better understand the response of terrestrial and aquatic ecosystems to Late-glacial climatic fluctuations. The multi-proxy record suggests that in the Oldest Dryas, the landscape around Lake Bled was rather open, presumably because of the cold and dry climate, with a trend towards wetter conditions, as suggested by an increase in tree pollen as well as chironomid and cladocera faunas typical for well-oxygenated water. Climatic warming at the beginning of the Late-glacial Interstadial at ca. 14,800 cal yr BP is suggested by an increase in the δ¹⁸O value, the appearance of Betula and Larix pollen and macrofossils, and a warmth-adapted chironomid fauna. With further warming at ca. 13,800 cal yr BP, broad-leaved tree taxa (Quercus, Tilia, Ulmus), Artemisia, and Picea increase, whereas chironomid data (Cricotopus B) suggest lowering of lake levels. After 12,800 cal yr BP (and throughout the Younger Dryas), the climate was colder and drier, as indicated by lower δ¹⁸O values, decline of trees, increase of microscopic charcoal, xerophytes and littoral chironomids. A warmer climate, together with the spread of broad-leaved tree taxa and a deeper, more productive lake, mark the onset of the Late-glacial/Holocene transition. These results suggest that terrestrial and aquatic ecosystems at Lake Bled were very dynamic and sensitive to Late-glacial climatic fluctuations. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorised users. Guest editors: K. Buczkó, J. Korponai, J. Padisák & S. W. Starratt Palaeolimnological Proxies as Tools of Environmental Reconstruction in Fresh Water     

Environmental inferences and chironomid-based temperature reconstructions from fragmentary records of the Weichselian Early Glacial and Pleniglacial periods in the Niederlausitz area (eastern Germany)

We inferred past climate conditions from lacustrine sediments intercalated in Weichselian Early Glacial and Early Pleniglacial fluvial and aeolian sediments, exposed in two opencast lignite mines from the Niederlausitz area (eastern Germany). A chronology was established using radiocarbon and luminescence dating methods. Both lithology and chironomid fauna indicate that the former shallow lakes were situated on a floodplain. Palaeotemperature estimates calculated from the fossil chironomid-assemblages of the Early Glacial lacustrine deposit indicate mean July air temperatures of ca. 15 °C, which is in line with results derived in earlier studies from the Niederlausitz area and from northwestern Europe. The Early Pleniglacial lacustrine deposits consist of an organic-rich gyttja, intercalated with sand and silt lenses. The chironomid-assemblages show that a shallow meso- to eutrophic lake was present at the study site, and chironomid-inferred palaeotemperature estimates indicate an abrupt decline in July air temperatures from 15–16 °C to ca. 13 °C. In combination with other proxies from the same record, this suggests a Dansgaard/Oeschger like climate event.     

Climate during the Eemian in north-central Europe — a critical review of the palaeobotanical and stable isotope data from central Germany

This paper reviews the evidence from terrestrial palaeoenvironmental records in north-central Europe and, in particular, central Germany, which relates to the controversial proposition that there were strong climate oscillations during the last interglacial (oxygen isotope substage 5e). In contrast to the evidence from the GRIP ice core at Summit, Greenland, and a recent palaeoclimate reconstruction based on the pollen profile from Bispingen, Germany, the evaluation of the palaeobotanical and the stable isotope data presented here strongly suggests relatively stable temperature for most of the Eemian and with instability confined to the beginning and end of the interglacial. High amplitude temperature variations can be seen in both the Early Weichselian pollen and isotope records. It is argued that this pattern of climate development is applicable to most of continental north-central Europe.     

Upland vegetation in the north-west Iberian peninsula after the last glaciation: Forest history and deforestation dynamics

This paper presents the results of pollen analyses from organic sediments of seven cores (299 spectra) in a mountainous area of the north-west Iberian peninsula. The pollen diagrams, supported by seven¹⁴C dates, are used to construct a regional pollen sequence covering the main stages of vegetation dynamics, from the last phases of the Late-glacial until the present. During the Late-glacial Interstadial an important development of cryophilous forests (Betula andPinus) was recorded, although various mesophilous and thermophilous tree elements were also present. The Younger Dryas, palynologically clearly defined, is characterized by an important reduction in tree pollen percentages and the expansion of steppe formations (Poaceae andArtemisia). At the beginning of the Holocene, there was an expansion ofQuercus and a spread of other trees, which combined to give a vegetation cover of varied composition but dominated by mixed deciduous forests. Such forest formations prevailed in these mountains until 3000 years ago, when successive deforestation phases are recorded at various times as a result of increased farming activity. The results are compared with data from other mountainous areas in the northern Iberian peninsula and southern France.