304 research outputs found
Evidencias antrópicas en las secuencias polínicas de la península Ibérica y la península Itálica. Sincronismos, diacronismos y su relación con las tendencias climáticas de los últimos milenios
XV lnternational A.P.L.E. Symposium of Palynolog
The establishment of the agricultural landscape of central Sicily between the Middle Neolithic and the beginning of the Iron Age
The possible co-variation of human occupation and vegetation from the Middle Neolithic to the beginning of the Iron Age (7.5–2.8 ka BP) in Central Sicily in the context of the central Mediterranean between Middle and Late Holocene are analysed in this paper to provide new insights on Sicilian prehistoric demography. The demographic and economic trends during these millennia were reconstructed using archaeological, Accelerator Mass Spectrometry 14C dates, palynological, archaeobotanical, and zooarchaeological data from the northern, central, and southern sectors of Central Sicily through a diachronic comparison with variation in Arboreal Pollen, Anthropogenic Pollen Indicators, Olea-Juglans-Castanea pollen, microcharcoals, and Sporormiella from four pollen cores from sites in different ecosystems. A very significant spread of farming activities was found at the end of the Neolithic, together with an apparent demographic gap during the Middle Copper Age, and the emergence of agricultural landscapes at the end of the Copper Age associated with a striking increase in population. A combination of cultural and climatic changes during the late phase of the Bronze Age resulted in a subsequent overall decrease in population
Vegetation, climate and environmental history of the last 4500 years at lake Shkodra (Albania/Montenegro)
Three parallel overlapping cores have been taken in the Albanian side of Lake Shkodra (Albania/Montenegro). The chronological frame of the record, spanning approximately the last 4500 years, has been assessed using four radiocarbon dates and four well-known tephra layers of Italian volcanoes. Multidisciplinary analyses turned out to be decisive to understand environmental, climatic changes and human impact. Here, we focus on palynology. The humidity at Shkodra was always enough to allow the developing of a luxuriant arboreal vegetation. The pollen percentage diagram does not record important changes in terrestrial plants percentages. Arboreal pollen (AP) shows only a rather slight decrease, with ‘natural forests’ replaced by intensive cultivation of chestnut and walnut in the last seven/eight centuries. The rather minimal changes in composition and dominance are because of the fact that the pollen rain comes from different vegetation belts, from the Mediterranean to the alpine one. Two major periods of humidity are found, one at the base of the pollen concentration and influx diagram, before 4100 yr BP, the other at 1300 yr BP. Minima in pollen influx and concentration occurred soon before 4000, at ca. 2900 and at ca. 1450 yr BP These minima, interpreted as aridity crises, show a temporal coincidence with the so-called Bond events 1-3 already found in other central and eastern Mediterranean records. The minimum in AP occurring after 500 yr BP could represent the record of the ‘Little Ice Age’, even if it could be the effect of a strong land use
At the origins of Pompeii: the plant landscape of the Sarno River floodplain from the first millennium bc to the ad 79 eruption
The ad 79 eruption of the Vesuvius severely affected the floodplain surrounding the ancient city of Pompeii, i.e. the Sarno River floodplain. The landscape was covered with volcaniclastic materials that destroyed the ecosystem but, at the same time, preserved the traces of former environmental conditions. This study provides—for the first time—a pollen sequence reconstructing the environmental evolution and the plant landscape of the Sarno floodplain between 900 and 750 cal bc and ad 79, i.e. before and during the foundation of the city, and during its life phases. Previous geomorphological studies revealed that the portion of the Sarno floodplain under the “Pompeii hill” was a freshwater backswamp with patchy inundated and dry areas. Palynology depicts a thin forest cover since the Early Iron Age, suggesting an open environment with a mosaic of vegetation types. The local presence of Mediterranean coastal shrubland, hygrophilous riverine forest and mesophilous plain forest is combined with the regional contribution of mountain vegetation through the sequence. Oscillations between inundated and wet ground characterized the studied area until the ad 79 eruption. Such a natural environment shows anthropogenic traits since pre-Roman times: pasturelands, cultivated fields and olive groves, which probably occupied drier soils. The most important change in the land use system was the introduction of cabbage cultivation in the fourth century bc and its intensification from the second century bc, when Roman influence grew. The presence of tree crops and of ornamental trees reveals the opulence of the Imperial age until the catastrophic eruption
Corrigendum to “Pollen-based paleoenvironmental and paleoclimatic change at Lake Ohrid (south-eastern Europe) during the past 500 ka” published in Biogeosciences, 13, 1423–1437, 2016
In this corrigendum we report an updated pollen record from the Lake Ohrid DEEP site spanning the past 500 ka whereby we have reprocessed and re-analyzed 104 samples affected by chemical procedure problems that occurred in one palynological laboratory. Firstly, these samples were affected by the use of wrong containers, causing in- adequate settling of particles at the set centrifuging speed. Secondly, HCl and HF treatments were combined without the prescribed intermediate centrifuging and decanting steps. The inaccuracy in the protocol resulted in the loss of smaller pollen grains and in the overrepresentation of bisaccate ones in most of the re-analyzed samples. We therefore provide an updated set of figures with the new data and have revised the description of the results, discussion and conclusions re- ported in Sadori et al. (2016) where necessary. We stress that the majority of the original results and conclusions remain valid, while the records’ reliability and resolution have improved as 12 samples that had been omitted in the original study because of low count sums are now included in the revised dataset (Sadori et al., 2018)
Discriminating the-long distance dispersal of fine ash from sustained columns or near ground ash clouds: the example of the Pomici di Avellino eruption (Somma-Vesuvius, Italy).
Ash samples from tephra layers correlated with the Pomici di Avellino (Avellino Pumice) eruption
of Somma-Vesuvius were collected in distal archives and their composition and particle
morphology investigated in order to infer their behaviour of transportation and deposition.
Differences in composition and particle morphologies were recognised for ash particles belonging
to the magmatic Plinian and final phreatomagmatic phases of the eruption. The ash particles were
dispersed in opposite directions during the two different phases of the eruption, and these directions
are also different from that of coarse-grained fallout deposits. In particular, ash generated during
magmatic phase and injected in the atmosphere to form a sustained column shows a prevailing SE
dispersion, while ash particles generated during the final phreatomagmatic phase and carried by
pyroclastic density currents show a general NW dispersion. These opposite dispersions indicate an
ash dispersal influenced by both high and low atmosphere dynamics. In particular, the magmatic
ash dispersal was first driven by stratospheric wind towards NE and then the falling particles
encountered a variable wind field during their settling, which produced the observed preferential SE
dispersal. The wind field encountered by the rising ash clouds that accompanied the pyroclastic
density currents of the final phreatomagmatic phase was different with respect to that encountered
by the magmatic ash, and produced a NW dispersal. These data demonstrate how ash transportation
and deposition are greatly influenced by both high and low atmosphere dynamics. In particular,
fine-grained particles transported in ash clouds of small-scale pyroclastic density currents may be
dispersed over distances and cover areas comparable with those injected into the stratosphere by
Plinian, sustained columns. This is a point not completely addressed by present day mitigation plans
in case of renewal of activity at Somma-Vesuvius, and can yield important information also for
other volcanoes potentially characterised by explosive activity
Pollen-based temperature and precipitation changes in the Ohrid Basin (western Balkans) between 160 and 70 ka
Our study aims to reconstruct climate changes that occurred at Lake Ohrid
(south-western Balkan Peninsula), the oldest extant lake in Europe, between
160 and 70 ka (covering part of marine isotope stage 6, MIS 6; all of MIS 5;
and the beginning of MIS 4). A multi-method approach, including the “Modern
Analog Technique” and the “Weighted Averaging Partial Least-Squares Regression”, is
applied to the high-resolution pollen sequence of the DEEP site, collected
from the central part of Lake Ohrid, to provide quantitative estimates of
climate and bioclimate parameters. This allows us to document climatic change
during the key periods of MIS 6 and MIS 5 in southern Europe, a region where
accurate climate reconstructions are still lacking for this time interval.
Our results for the penultimate glacial show cold and dry conditions, while the onset of
the “last interglacial” is characterized by wet and warm conditions, with temperatures
higher than today (by ca. 2 ∘C). The Eemian also shows the well-known climatic
tri-partition in the Balkans, with an initial pre-temperate phase of abrupt warming
(128–121 ka), a central temperate phase with decreasing temperatures associated with
wet conditions (121–118 ka), followed by a post-temperate phase of progressive change
towards cold and dry conditions (118–112 ka).
After the Eemian, an alternation of four warm/wet periods with cold/dry
ones, likely related to the succession of Greenland stadials and cold events
known from the North Atlantic, occurred. The observed pattern is also
consistent with hydrological and isotopic data from the central
Mediterranean.
The Lake Ohrid climate reconstruction shows greater similarity with climate
patterns inferred from northern European pollen records than with southern
European ones, which is probably due to its intermediate position and the
mountainous setting. However, this hypothesis needs further testing as very
few climate reconstructions are available for southern Europe for this key
time period.</p
Aligning MIS5 proxy records from Lake Ohrid (FYROM) with independently dated Mediterranean archives: implications for core chronology
The DEEP site sediment sequence obtained during the ICDP SCOPSCO project at Lake Ohrid was dated using tephrostratigraphic information, cyclostratigraphy, and orbital tuning through marine isotope record. Although this approach is suitable for the generation of a general chronological framework of the long succession, it is insufficient to resolve more detailed paleoclimatological questions, such as leads and lags of climate events between marine and terrestrial records or between different regions. In this paper, we demonstrate how the use of different tie points can affect cyclostratigraphy and orbital tuning for the period between ca. 140 and 70 ka and how the results can be correlated with directly/indirectly radiometrically-dated Mediterranean marine and continental proxy records. The alternative age model obtained shows consistent differences with that proposed by Francke et al. (2015) for the same interval, in particular at the level of the MIS6-5e transition. According to this age model, different proxies from the DEEP site sediment record support an increase of temperatures between glacial to interglacial conditions, which is almost synchronous with a rapid increase in sea surface temperature observed in the western Mediterranean. The results show how important a detailed study of independent chronological tie points is for synchronizing different records and to highlight asynchronisms of climate events
Insight into summer drought in southern Italy: palaeohydrological evolution of Lake Pergusa (Sicily) in the last 6700 years
The Sicily region (central Mediterranean) is at high risk of drying and desertification caused by current warming and land management. The aim of this study is to place current climatic changes within the past trajectories and natural climatic variability of the Holocene. For this we re-examine a sediment core retrieved at Lake Pergusa covering the last ca. 6700 years. A multiproxy investigation, and in particular the oxygen isotope composition of lacustrine carbonate (delta O-18(c)), allowed us to reconstruct decadal- to centennial-scale hydrological changes. The wettest period occurred between ca. 6700 and 6000 cal a bp. The delta O-18(c) record indicates a new period of wetter conditions between ca. 3700 and 2400 cal a bp. In particular, a delta O-18(c) minimum between 2850 and 2450 cal a bp overlaps with the period of the 'Great Solar Minimum' and corresponds to a dramatic reduction of arboreal pollen (AP%) and to an increase in synanthropic pollen, marking the onset of Greek colonization in the region. The longest driest interval corresponds to the Medieval Climate Anomaly, whereas the highest delta O-18(c) values are recorded in the last 150 years. The trend of the last 3000 years suggests that, considering future climate projections, the area will experience unprecedented drying exacerbated by human impact
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