Elena Ortu

Towards mapping the late Quaternary vegetation change of Europe

The number of well-dated pollen diagrams in Europe has increased considerably over the last 30xa0years and many of them have been submitted to the European Pollen Database (EPD). This allows for the construction of increasingly precise maps of Holocene vegetation change across the continent. Chronological information in the EPD has been expressed in uncalibrated radiocarbon years, and most chronologies to date are based on this time scale. Here we present new chronologies for most of the datasets stored in the EPD based on calibrated radiocarbon years. Age information associated with pollen diagrams is often derived from the pollen stratigraphy itself or from other sedimentological information. We reviewed these chronological tie points and assigned uncertainties to them. The steps taken to generate the new chronologies are described and the rationale for a new classification system for age uncertainties is introduced. The resulting chronologies are fit for most continental-scale questions. They may not provide the best age model for particular sites, but may be viewed as general purpose chronologies. Taxonomic particularities of the data stored in the EPD are explained. An example is given of how the database can be queried to select samples with appropriate age control as well as the suitable taxonomic level to answer a specific research question.

The European Modern Pollen Database (EMPD) project

Modern pollen samples provide an invaluable research tool for helping to interpret the quaternary fossil pollen record, allowing investigation of the relationship between pollen as the proxy and the environmental parameters such as vegetation, land-use, and climate that the pollen proxy represents. The European Modern Pollen Database (EMPD) is a new initiative within the European Pollen Database (EPD) to establish a publicly accessible repository of modern (surface sample) pollen data. This new database will complement the EPD, which at present holds only fossil sedimentary pollen data. The EMPD is freely available online to the scientific community and currently has information on almost 5,000 pollen samples from throughout the Euro-Siberian and Mediterranean regions, contributed by over 40 individuals and research groups. Here we describe how the EMPD was constructed, the various tables and their fields, problems and errors, quality controls, and continuing efforts to improve the available data.

Role de l'homme dans l'histoire de la vegetation de la vallee Ellero (Alpes maritimes, Italie)

Resume Lanalyse pollinique dune sequence sedimentaire dune tourbiere de letage montagnard de la vallee Ellero (Rifugio Mondovi, 1760 m, Alpes maritimes italiennes) met en evidence les particularites de lhistoire postglaciaire de la vegetation du piemont italien. Le debut de lenregistrement vers 12000 BP pendant loptimum du pin se distingue par une faible representation du bouleau et loccurrence de chene caducifolie et de tilleul. Le Dryas recent est caracterise par une progression darmoises, recelant des occurrences de chene caducifolie, de sapin et de hetre. Lorme est enregistre au debut de lHolocene, pendant le second optimum des pins (9800 BP). Un long hiatus denviron 3000 ans est enregistre. La reprise de la sedimentation vers 6000xa0BP se fait dans une sapiniere a rhododendrons. La transition actuelle a 1500xa0m entre les hetraies et les pelouses, semblable a celle que lon retrouve dans les Apennins, resulte de laction humaine en deux etapes : vers 2600 BP, la sapiniere decline au profit du hetre, les chenes decidus et les graminees progressent et le chene vert apparait. Vers 1800 BP, le developpement du meleze est enregistre, avec celui du noyer, du châtaignier, des cereales et de la vigne. Pour citer cet article : E.xa0Ortu etxa0al., C.xa0R. Biologies 326 (2003).

Late Glacial and Holocene vegetation dynamics at various altitudes in the Ellero Valley, Maritime Alps, northwestern Italy

ABSTRACT This study aims to reconstruct the variations in the vegetation zonation in the Ellero Valley (Maritime Alps, Italy) since the Late Glacial. Based on analysis of percentages of dominant pollen taxa (Pinus, Abies, Fagus, deciduous Quercus, Artemisia, Poaceae) in sediment cores from 3 peat bogs at different altitudes (Pian Marchisio, 1624 m; Rifugio Mondovì, 1760 m; and Torbiera del Biecai, 1920 m), this study offers an interpretation of pollen percentages in terms of vegetation cover The correlation of the pollen zones in the 3 diagrams is validated by correspondence analysis and supported by 12 14C (AMS) dates. The Oldest and the Younger Dryas were characterized by steppe vegetation dominated by Artemisia. The Bølling–Allerød warming, which separates the Oldest and the Younger Dryas, is characterized by a Pinus shift. Pine and birch forests develop at 1900 m asl at the beginning of the Holocene. The fir wood colonization of the mountainous and subalpine belts is dated to 9540–9406 cal BP and follows these first phases. Fir development and the arrival of beech are dated 8767–8543 cal BP: beech is recorded about 1000–2000 y earlier than in the adjacent regions. Beech forests develop between 1100 and 1600 m asl, forming a vegetation belt between the oak-wood in the lowland and the subalpine fir-wood. Fir decreases from 2792–2459 cal BP. Since this period, a beech–fir mountainous belt has been present at 1700 m. Both the suppression of the fir forest and the lowering of the upper beech wood limit to 1500 m are due to human activity during the last millennium. Nomenclature: Pignatti, 1982.

Erratum to: The European Modern Pollen Database (EMPD) project

Unfortunately, the list of authors contains a number of duplications, omissions and other errors in the original publication of the article. The correct list appears in this erratum.