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

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&thinsp;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&thinsp;∘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&thinsp;ka), a central temperate phase with decreasing temperatures associated with wet conditions (121–118&thinsp;ka), followed by a post-temperate phase of progressive change towards cold and dry conditions (118–112&thinsp;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

Sedimentological processes and environmental variability at Lake Ohrid (Macedonia, Albania) between 640 ka and present day

Lake Ohrid (FYROM, Albania) is thought to be more than 1.2 million years old and hosts more than 200 endemic species. As a target of the International Continental Scientific Drilling Program (ICDP), a successful deep drilling campaign was carried out within the scope of the Scientific Collaboration on Past Speciation Conditions in Lake Ohrid (SCOPSCO) project in 2013. Here, we present lithological, sedimentological, and (bio-)geochemical data from the upper 247.8 m of the overall 569 m long DEEP site sediment succession from the central part of the lake. According to an age model, which is based on nine tephra layers (1st order tie points), and on tuning of biogeochemical proxy data to orbital parameters (2nd order tie points) and to the global benthic isotope stack LR04 (3rd order tie points), respectively, the analyzed sediment sequence covers the last 640 ka

Rome in its setting. Post-glacial aggradation history of the Tiber River alluvial deposits and tectonic origin of the Tiber Island

Support for this work was provided by the DTS-MIUR NextData project, the University of Michigan, the Etruscan Foundation, and the Fondazione Lemmermann. This work includes data collected with funding from the National Science Foundation under Grant No. 1259122 (ALB).The Tiber valley is a prominent feature in the landscape of ancient Rome and an important element for understanding its urban development. However, little is known about the city’s original setting. Our research provides new data on the Holocene sedimentary history and human-environment interactions in the Forum Boarium, the location of the earliest harbor of the city. Since the Last Glacial Maximum, when the fluvial valley was incised to a depth of tens of meters below the present sea level, 14C and ceramic ages coupled with paleomagnetic analysis show the occurrence of three distinct aggradational phases until the establishment of a relatively stable alluvial plain at 6–8 m a.s.l. during the late 3rd century BCE. Moreover, we report evidence of a sudden and anomalous increase in sedimentation rate around 2600 yr BP, leading to the deposition of a 4-6m thick package of alluvial deposits in approximately one century. We discuss this datum in the light of possible tectonic activity along a morpho-structural lineament, revealed by the digital elevation model of this area, crossing the Forum Boarium and aligned with the Tiber Island. We formulate the hypothesis that fault displacement along this structural lineament may be responsible for the sudden collapse of the investigated area, which provided new space for the observed unusually large accumulation of sediments. We also posit that, as a consequence of the diversion of the Tiber course and the loss in capacity of transport by the river, this faulting activity triggered the origin of the Tiber Island.Publisher PDFPeer reviewe