Weichselian palynostratigraphy, palaeovegetation and palaeoenvironment; the record from Lago Grande di Monticchio, southern Italy
Introduction
Lago Grande di Monticchio (40°56′40″N, 15°36′30″E; 656 m above sea level) is a Maar lake situated in the volcanic crater on the western flank of Monte Vulture in Basilicata, southern Italy (Fig. 1). The inner flanks of the crater are forested, the dominant canopy species being Fagus sylvatica and Quercus cerris. The shrub layer is dominated by Ilex aquifolium and Corylus avellana; Hedera helix and Ruscus aculeatus are also prominent, along with a species-rich herbaceous flora that is central European in biogeographic character. Monte Vulture, which rises to 1326 m, has today an Abies woodland on its summit. This stand, however, is not natural but the result of planting earlier this century. A more detailed account of the general setting of the site has been given elsewhere (Watts et al., 1996a, Watts et al., 1996b).
The site has several important features that combine to make its sedimentary record unique amongst European terrestrial records spanning the last glacial stage. Firstly, it lies far enough south to have suffered no direct effects of the Weichselian glaciation, yet is sufficiently close to, and `downwind’ of, the North Atlantic for its climate to be influenced by weather systems that reflect conditions in that ocean basin (Conte and Colacino, 1995). Secondly, the lake has a spatially restricted hydrological catchment within the steep-sided crater of Monte Vulture and has only intermittently overflowed, apparently never having had any substantial throughput of water. The deeper part of the basin has been continuously flooded; therefore, not only have conditions been ideal for the preservation of micro-fossils, but also sediments have accumulated continuously providing a sedimentary record with no major hiatuses since the formation of the lake. Thirdly, the sediments are, for much of the stratigraphic sequence, laminated, enabling the establishment of a calendar year chronology based upon numerous measurements of sedimentation rates (Jens Mingram, pers. commun.; Zolitschka and Negendank, 1993, Zolitschka and Negendank, 1996). Furthermore, the sedimentary sequence includes numerous tephra layers; although the majority of these are thin (<10 mm), a number are >100 mm thick. Some of the latter have been directly dated by (Watts et al., 1996b), whereas others have been dated by tephrochronological correlations (Sabine Wulf, pers. commun.; Narcisi, 1996; Allen et al., 1999): Although in some cases there are discrepancies between the and sedimentation-rate-based ages, given the errors associated with the technique when applied to such young deposits, the results generally support the sedimentation rate chronology. Radiocarbon age measurements made upon carefully selected terrestrial macrofossils also corroborate the recent part of the chronology (Hajdas et al., 1998).
The sediments have been the subject of multidisciplinary studies for the last 18 years (Watts, 1985; Turton, 1993; Zolitschka and Negendank, 1993, Zolitschka and Negendank, 1996; Robinson, 1994; Narcisi, 1996; Watts et al., 1996a, Watts et al., 2000; Allen et al., 1999; Brandt et al., 1999; Huntley et al., 1999; Nimmergut et al., 1999); the most recent coring of the site, utilising equipment from GFZ Potsdam, Germany, took place in 1994 and extended the record to 71 m. Here we present the complete record in detail for the first time; this record is based on analyses of the two main cores (D (1990) and J (1994)). These have been securely cross-correlated using a series of thick (>100 mm) and morphologically characteristic tephra layers, enabling the composite stratigraphic sequence to be constructed that has then been used to compile a 101,530 calendar year continuous palynological record for the site.
Palynologists generally interpret the results of their pollen analyses in terms of rather subjective and qualitative inferences as to the character of the palaeovegetation represented by the pollen spectra. They often also infer aspects of the palaeoenvironment, especially the palaeoclimate, in a similar manner. In both cases the inferences are based upon the palynologists’ knowledge of the present ecological character and spatial occurrence of the plant taxa represented in the fossil assemblages. We present below such subjective interpretations of the palynological data from Monticchio. In recent years, however, attention has focussed upon the development of more systematic and/or quantitative methods for making palaeovegetation and palaeoenvironment reconstructions. These methods too are based upon knowledge of the ecological character and present patterns of occurrence of plant taxa, although now this information is expressed and utilised in a more systematic manner. We have applied such systematic palaeovegetation and quantitative palaeoclimate reconstruction techniques to our palynological data spanning the last 101,530 yr. These results are also presented below, complementing the subjective inferences and providing the basis for comparisons with other palaeoenvironmental records from marine sediments and ice-cores spanning the same interval. The conclusions that emerge from such comparisons with respect to Weichselian palaeoclimates, in particular, are discussed.
Section snippets
Palynostratigraphy
Pollen counts have been made for 496 sub-samples taken from the 71 m composite sedimentary sequence; each sub-sample spans 7 mm and the mean depth interval between sub-samples is 140 mm. Ages have been assigned to each sub-sample according to the sedimentation rate chronology; the resulting mean temporal interval between sub-samples is 200 yr, with each sub-sample representing ca. 10 yr. Pollen was extracted using standard (heavy liquid) techniques and mounted in silicone oil for examination under a
Palaeovegetation and palaeoenvironment
Whether the techniques adopted are subjective and qualitative or systematic and quantitative, the character of the palaeovegetation and palaeoenvironment can be inferred from palynological data using a variety of approaches. The most appropriate approach(es) in any particular study will depend in part upon the taxonomic resolution of the data available, in particular upon whether macrofossil as well as palynological data have been recorded, but will be determined principally by the spatial
Discussion
The complex palynological record from Lago Grande di Monticchio shows that the vegetation and climate of southern Italy have varied continually during the past 101,530 yr, not only on the multi-millennial time scale reflected by the three broad sub-divisions of the record discussed earlier, but also on millennial and sub-millennial time scales. Indeed, higher temporal resolution studies of parts of the record (Huntley et al., 1999; Nimmergut et al., 1999) have shown that the palynostratigraphy
Acknowledgements
The 1990 coring campaign and the pollen analyses of core D at Lago Grande di Monticchio were made possible by research contracts from the EC to the Euromaars project, as part of the EPOCH programme (contract EPOCH-004), and as part of the EC Framework 3 `Environment’ programme (contract EVSV-CT92-1033). The 1994 coring campaign was made possible by financial support from the GeoForschungsZentrum Potsdam (GFZ) and was carried out as a component of the GFZ research project `Monticchio'. We are
References (53)
- et al.
Weichselian palynological records from southern Europe: correlation and chronology
Quaternary International
(2000) Biostratigraphy of the last glacial period in Europe
Quaternary Science Reviews
(1989)Long term variations of caloric insolation resulting from the Earth's orbital elements
Quaternary Research
(1978)- et al.
Palaeomagnetism of Holocene and Late Pleistocene sediments from Lago di Mezzano and Lago Grande di Monticchio (Italy) — first results
Quaternary Science Reviews
(1999) - et al.
The last climatic cycle at La Grande Pile (Vosges, France). A new pollen profile
Quaternary Science Reviews
(1992) - et al.
Palynostratigraphy of the last glacial period in the volcanic region of central Italy
Quaternary International
(1998) Origin and consequences of cyclic ice rafting in the Northeast Atlantic Ocean during the past 130,000 years
Quaternary Research
(1988)- et al.
Palaeoclimate, chronology and vegetation history of the Weichselian Late-glacialcomparative analysis of data from three cores at Lago Grande di Monticchio, southern Italy
Quaternary Science Reviews
(1999) - et al.
Age dating and the orbital theory of the ice agesdevelopment of a high-resolution 0 to 300,000-year chronostratigraphy
Quaternary Research
(1987) Tephrochronology of a late Quaternary lacustrine record from the Monticchio Maar (Vulture Volcano Southern Italy)
Quaternary Science Reviews
(1996)
Lago Grande di Monticchio, southern Italya long record of environmental change illustrated by sediment geochemistry
Chemical Geology
Vegetation history and palaeoclimate of the Last Glacial period at Lago Grande di Monticchio, southern Italy
Quaternary Science Reviews
Palaeoecology of three interstadial events during oxygen-isotope stages 3 and 4a lacustrine record from Lago Grande di Monticchio, southern Italy
Palaeogeography, Palaeoclimatology, Palaeoecology
Vegetation history and climate of the last 15,000 years at Laghi di Monticchio, southern Italy
Quaternary Science Reviews
Grande Pile peat boga continuous pollen record for the last 140,000 years
Quaternary Research
Sedimentology, dating and palaeoclimatic interpretation of a 76.3 ka record from Lago Grande di Monticchio, southern Italy
Quaternary Science Reviews
Evidence of rapid last glacial environmental fluctuations from southern Europe
Nature
Climatic response surfaces from pollen data for some eastern North American taxa
Journal of Biogeography
Towards an absolute chronology for the last glacial period in Europeradiocarbon dates from Oerel, northern Germany
Vegetation History and Archaeobotany
Climate correlations between Greenland and Antarctica during the past 100,000 years
Nature
Correlations between climate records from North Atlantic sediments and Greenland ice
Nature
Evidence for massive discharges of icebergs into the North Atlantic ocean during the last glacial period
Nature
A pervasive millennial-scale cycle in North Atlantic Holocene and glacial climates
Science
Iceberg discharges into the North Atlantic on millennial time scales during the last glaciation
Science
Evidence for general instability of past climate from a 250-kyr ice-core record
Nature
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