scholarly journals Harmonized chronologies of a global late Quaternary pollen dataset (LegacyAge 1.0)

2021 ◽  
Author(s):  
Chenzhi Li ◽  
Alexander K. Postl ◽  
Thomas Böhmer ◽  
Xianyong Cao ◽  
Andrew M. Dolman ◽  
...  
Keyword(s):  
Optimal Parameter ◽  
Late Quaternary ◽  
Control Points ◽  
Radiocarbon Dates ◽  
Common Control ◽  
Preliminary Model ◽  
Palynological Records ◽  
Vegetation And Climate ◽  
Northern And Southern Hemispheres ◽  
Pollen Records

Abstract. Although numerous pollen records are available worldwide in various databases, their use for synthesis works is limited as the chronologies are, as yet, not harmonized globally, and temporal uncertainties are unknown. We present a chronology framework named LegacyAge 1.0 that includes harmonized chronologies of 2831 palynological records (out of 3471 available records), downloaded from the Neotoma Paleoecology Database (last access: April 2021) and 324 additional Asian records. All chronologies use the Bayesian framework implemented in Bacon version 2.5.3. Optimal parameter settings of priors (accumulation.shape, memory.strength, memory.mean, accumulation.rate, thickness) were identified based on previous experiences or iteratively after preliminary model inspection. The most common control points for the chronologies are radiocarbon dates (86.1 %), calibrated by the latest calibration curves (IntCal20 and SHcal20 for the terrestrial radiocarbon dates in the northern and southern hemispheres; Marine20 for marine materials). The original literature was consulted when dealing with obvious outliers and inconsistencies. Several major challenges when setting up the chronologies included the waterline issue (18.8 % of records), reservoir effect (4.9 %), and sediment deposition discontinuity (4.4 %). Finally, we numerically compare the LegacyAge 1.0 chronologies to the original ones and show that the chronologies of 95.4 % of records could be improved according to our assessment. Our chronology framework and revised chronologies provide the opportunity to make use of the ages and age uncertainties in synthesis studies of, for example, pollen-based vegetation and climate change. The LegacyAge 1.0 dataset and R code used are open-access and available at PANGAEA (https://doi.pangaea.de/10.1594/PANGAEA.933132) and Github (https://github.com/LongtermEcology/LegacyAge-1.0), respectively.

Late Quaternary Vegetation and Climate of Southern Tierra del Fuego

1989 ◽  
Vol 31 (3) ◽  
pp. 396-406 ◽  
Author(s):  
Calvin J. Heusser
Keyword(s):  
Late Quaternary ◽  
Pollen Dispersal ◽  
Late Glacial ◽  
Tierra Del Fuego ◽  
Fossil Pollen ◽  
Radiocarbon Dates ◽  
Modern Pollen ◽  
Open Woodland ◽  
Glacial Time ◽  
Vegetation And Climate

AbstractVegetation and climate over approximately the past 13,000 yr are reconstructed from fossil pollen in a 9.4-m mire section at Caleta Róbalo on Beagle Channel, Isla Navarino (54°56′S, 67°38′W), southern Tierra del Fuego. Fifty surface samples reflecting modern pollen dispersal serve to interpret the record. Chronologically controlled by nine radiocarbon dates, fossil pollen assemblages are: Empetrum-Gramineae-Gunnera-Tubuliflorae (zone 3b, 13,000–11,850 yr B.P.), Gramineae-Empetrum-assorted minor taxa (zone 3a, 11,850-10,000 yr B.P.), Nothofagus-Gramineae-Tubuliflorae-Polypodiaceae (zone 2, 10,000–5000 yr B.P.), Nothofagus-Empetrum (zone 1b, 5000-3000 yr B.P.), and Empetrum-Nothofagus (zone 1a, 3000-0 yr B.P.). Assemblages show tundra under a cold, dry climate (zone 3), followed by open woodland (zone 2), as conditions became warmer and less dry, and later, with greater humidity and lower temperatures, by closed forest and the spread of mires (zone 1). Comparisons drawn with records from Antarctica, New Zealand, Tasmania, and the subantarctic islands demonstrate broadly uniform conditions in the circumpolar Southern Hemisphere. The influences of continental and maritime antarctic air masses were apparently considerable in Tierra del Fuego during cold late-glacial time, whereas Holocene climate was largely regulated by interplay between maritime polar and maritime tropical air.

scholarly journals Vegetation and climate history in the Laptev Sea region (Arctic Siberia) during Late Quaternary inferred from pollen records

2011 ◽  
Vol 30 (17-18) ◽  
pp. 2182-2199 ◽  
Author(s):  
Andrei A. Andreev ◽  
Lutz Schirrmeister ◽  
Pavel E. Tarasov ◽  
Andrey Ganopolski ◽  
Viktor Brovkin ◽  
...  
Keyword(s):  
Late Quaternary ◽  
Laptev Sea ◽  
Climate History ◽  
Vegetation And Climate ◽  
The Laptev Sea ◽  
Arctic Siberia ◽  
Pollen Records

scholarly journals Late Quaternary vegetation and climate of SE Europe–NW Asia according to pollen records in three offshore cores from the Black and Marmara seas

2021 ◽  
Author(s):  
Speranta-Maria Popescu ◽  
Gonzalo Jiménez-Moreno ◽  
Stefan Klotz ◽  
Gilles Lericolais ◽  
François Guichard ◽  
...  
Keyword(s):  
Late Quaternary ◽  
Vegetation And Climate ◽  
Pollen Records

scholarly journals Two Late Quaternary Pollen Records from South-Central Alaska

2007 ◽  
Vol 48 (2) ◽  
pp. 131-143 ◽  
Author(s):  
P. M. Anderson ◽  
A. V. Lozhkin ◽  
W. R. Eisner ◽  
M. V. Kozhevnikova ◽  
D. M. Hopkins ◽  
...  
Keyword(s):  
Boreal Forest ◽  
Picea Glauca ◽  
Boreal Forests ◽  
Vegetation History ◽  
Late Quaternary ◽  
Radiocarbon Dates ◽  
The North ◽  
South Central ◽  
Future Global Warming ◽  
Pollen Records

ABSTRACT Pollen records from Wonder and Ten Mile lakes, located at aititudinal treeline to the north and south of the Alaska Range respectively, document the vegetation history of a portion of the southern Alaskan boreal forest. The new pollen diagrams indicate a Betula shrub tundra, preceded at Wonder Lake by a sparse herb tundra, which characterized these two areas during latest Wisconsinan times. Populus was in the vicinity of Ten Mile Lake ca. 10,000 BP, but was apparently absent from Wonder Lake. Picea glauca grew at or near Ten Mile Lake by 9100 BP, with P. mariana becoming important ca. 7000 BP. The first forests at Wonder Lake were also dominated by P. glauca and followed by increased numbers of P. mariana. The timing of forest establishment at Wonder Lake is uncertain due to problematic radiocarbon dates. Alnus appears to be common in both regions by ca. 7000 BP. These records suggest that paleo-vegetational reconstructions are more difficult for the southern than northern boreal forests in Alaska because of greater topographic diversity, difficulties with over-representation of some pollen taxa, and problems with radiocarbon dating. Despite these concerns, available data from south-central Alaska suggest that southern and northern forests differ in their vegetational histories. Such differences, when related to temperature fluctuations that have been postulated for the Holocene, imply that the Alaskan boreal forest may not respond uniformly to future global warming.

Absence of Last Glacial Maximum Records in Lowland Tropical Forests

1998 ◽  
Vol 49 (2) ◽  
pp. 233-237 ◽  
Author(s):  
Marie-Pierre Ledru ◽  
Jacques Bertaux ◽  
Abdelfettah Sifeddine ◽  
Kenitiro Suguio
Keyword(s):  
South America ◽  
Tropical Forests ◽  
Last Glacial Maximum ◽  
Sedimentation Rate ◽  
Glacial Maximum ◽  
Radiocarbon Dates ◽  
Last Glacial ◽  
The Last Glacial Maximum ◽  
Pollen Records ◽  
The Last Glacial

Environmental conditions of the lowland tropical forests during the last glacial maximum (LGM) between ca 20,000 and 18,000 14C yr B.P., are reevaluated in terms of dating control and lithology analyzed in seven pollen records from South America. The reevaluation shows that probably in none of the published records are LGM sediments present or abundant. This conclusion is based on the occurrence of abrupt lithologic changes coupled with changes in sedimentation rate interpolated from radiocarbon dates. These findings suggest that the LGM was represented probably by a hiatus of several thousand years, indicative of drier climates than before or after.

scholarly journals Vegetation and climate from Late Quaternary Thimi Formation (Phaidhoka Section), Bhaktapur, Nepal

2015 ◽  
Vol 50 (1) ◽  
pp. 1-12
Author(s):  
Deepak Banjade ◽  
Kabir Sharma ◽  
Khum N. Paudayal
Keyword(s):  
Late Quaternary ◽  
Middle Part ◽  
Temperate Climate ◽  
Silty Clay ◽  
Pollen Diagram ◽  
Formation Zone ◽  
Palynological Study ◽  
Deltaic Deposit ◽  
Warm Temperate ◽  
Vegetation And Climate

The Thimi Formation is fluvio-deltaic deposit that constitutes the uppermost part of the sedimentary sequence in the Kathmandu Basin, and is featured by carbonaceous and diatomaceous clay, silty clay, silt, fine to medium grained sand beds, and thin to medium lignite beds. The Phaidhoka Section is located on the way to Nala from Chyamasingh, and is one of the major exposures of the Thimi Formation. Forty four samples were collected from 25 m thick surface exposure for palynological study. The study revealed the dominance of gymnosperm over the angiosperm and herbaceous members. The pollen diagram suggested Pinus, Picea and Quercus as the most dominant trees whereas Poaceae is other dominant among the grasses. Three major pollen assemblage zones were marked in the Thimi Formation. Zone P-I indicated warm temperate climate, whereas zone P-II and P-III indicated cold temperate climate. Molluscan operculum in the upper part indicated shallow water condition. The Bovid molars, limb and pelvic bones from the middle part of the section confirm the early findings of molar bones in this area.

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