scholarly journals A taxonomically harmonized and temporally standardized fossil pollen dataset from Siberia covering the last 40 ka

2019 ◽  
Author(s):  
Xianyong Cao ◽  
Fang Tian ◽  
Andrei Andreev ◽  
Patricia M. Anderson ◽  
Anatoly V. Lozhkin ◽  
...  
Keyword(s):  
Northeast Asia ◽  
Original Data ◽  
Data Mapping ◽  
Pollen Data ◽  
Last Glacial Period ◽  
Pollen Counts ◽  
Palynological Records ◽  
Percentage Data ◽  
Pollen Records ◽  
The Last Glacial

Abstract. Pollen records from Siberia are mostly absent in global or Northern Hemisphere synthesis works. Here we present a taxonomically harmonized and temporally standardized pollen dataset that was synthesized using 173 palynological records from Siberia and adjacent areas (northeast Asia, 50°–180° E and 42°–75° N). Pollen data were taxonomically harmonized, that is the original 437 taxa were transformed to 106 combined pollen taxa. Age-depth models for all records were revised by applying a constant Bayesian age-depth modelling routine. The pollen dataset is available as count data and percentage data in a table format (taxa vs. samples) with age information for each sample. The dataset has relatively few sites covering the last glacial period between 40 and 11.5 cal ka BP (calibrated thousand years before present 1950 CE) particularly from the central and western part of the study area. In the Holocene period, the dataset has many sites from most of the area except the central part of Siberia. Of the 173 pollen records, 81 % of pollen counts were downloaded from open databases (GPD, EPD, Pangaea) and 10 % were contributions of the original data gatherers, while a few were digitized from publications. Most of the pollen records originate from peatlands (48 %) and lake sediments (33 %). Most of the records (83 %) have ≥ 3 dates allowing the establishment of reliable chronologies. The dataset can be used for various purposes including pollen data mapping (example maps for Larix at selected time-slices are shown) as well as quantitative climate and vegetation reconstructions. The datasets for pollen counts and pollen percentages are available at https://doi.pangaea.de/10.1594/PANGAEA.898616 (Cao et al., 2019).

scholarly journals A taxonomically harmonized and temporally standardized fossil pollen dataset from Siberia covering the last 40 kyr

2020 ◽  
Vol 12 (1) ◽  
pp. 119-135
Author(s):  
Xianyong Cao ◽  
Fang Tian ◽  
Andrei Andreev ◽  
Patricia M. Anderson ◽  
Anatoly V. Lozhkin ◽  
...  
Keyword(s):  
Original Data ◽  
Data Mapping ◽  
Pollen Data ◽  
Last Glacial Period ◽  
Pollen Counts ◽  
Data Source ◽  
Palynological Records ◽  
Percentage Data ◽  
Pollen Records ◽  
The Last Glacial

Abstract. Pollen records from Siberia are mostly absent in global or Northern Hemisphere synthesis works. Here we present a taxonomically harmonized and temporally standardized pollen dataset that was synthesized using 173 palynological records from Siberia and adjacent areas (northeastern Asia, 42–75∘ N, 50–180∘ E). Pollen data were taxonomically harmonized, i.e. the original 437 taxa were assigned to 106 combined pollen taxa. Age–depth models for all records were revised by applying a constant Bayesian age–depth modelling routine. The pollen dataset is available as count data and percentage data in a table format (taxa vs. samples), with age information for each sample. The dataset has relatively few sites covering the last glacial period between 40 and 11.5 ka (calibrated thousands of years before 1950 CE) particularly from the central and western part of the study area. In the Holocene period, the dataset has many sites from most of the area, with the exception of the central part of Siberia. Of the 173 pollen records, 81 % of pollen counts were downloaded from open databases (GPD, EPD, PANGAEA) and 10 % were contributions by the original data gatherers, while a few were digitized from publications. Most of the pollen records originate from peatlands (48 %) and lake sediments (33 %). Most of the records (83 %) have ≥3 dates, allowing the establishment of reliable chronologies. The dataset can be used for various purposes, including pollen data mapping (example maps for Larix at selected time slices are shown) as well as quantitative climate and vegetation reconstructions. The datasets for pollen counts and pollen percentages are available at https://doi.org/10.1594/PANGAEA.898616 (Cao et al., 2019a), also including the site information, data source, original publication, dating data, and the plant functional type for each pollen taxa.

scholarly journals Postglacial change of the floristic diversity gradient in Europe

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Thomas Giesecke ◽  
Steffen Wolters ◽  
Jacqueline F. N. van Leeuwen ◽  
Pim W. O. van der Knaap ◽  
Michelle Leydet ◽  
...  
Keyword(s):  
Climate Warming ◽  
Human Impacts ◽  
Current View ◽  
Floristic Diversity ◽  
Pollen Data ◽  
Last Glacial Period ◽  
Latitudinal Diversity Gradient ◽  
Diversity Gradient ◽  
Poleward Shift ◽  
The Last Glacial

AbstractClimate warming is expected to cause a poleward spread of species, resulting in increased richness at mid to high latitudes and weakening the latitudinal diversity gradient. We used pollen data to test if such a change in the latitudinal diversity gradient occurred during the last major poleward shift of plant species in Europe following the end of the last glacial period. In contrast to expectations, the slope of the gradient strengthened during the Holocene. The increase in temperatures around 10 ka ago reduced diversity at mid to high latitude sites due to the gradual closure of forests. Deforestation and the introduction of agriculture during the last 5 ky had a greater impact on richness in central Europe than the earlier climate warming. These results do not support the current view that global warming alone will lead to a loss in biodiversity, and demonstrate that non-climatic human impacts on the latitudinal diversity gradient is of a greater magnitude than climate change.

Climatic Reconstruction in Europe for 18,000 YR B.P. from Pollen Data

1998 ◽  
Vol 49 (2) ◽  
pp. 183-196 ◽  
Author(s):  
Odile Peyron ◽  
Joël Guiot ◽  
Rachid Cheddadi ◽  
Pavel Tarasov ◽  
Maurice Reille ◽  
...  
Keyword(s):  
Neural Network ◽  
Precipitation Anomaly ◽  
Present Climate ◽  
Pollen Data ◽  
Moisture Index ◽  
Pollen Types ◽  
Individual Taxon ◽  
The Last Glacial Maximum ◽  
Pollen Records ◽  
The Last Glacial

An improved concept of the best analogs method is used to reconstruct the climate of the last glacial maximum from pollen data in Europe. In order to deal with the lack of perfect analogs of fossil assemblages and therefore to obtain a more accurate climate reconstruction, we used a combination of pollen types grouped according to plant phenology and present climate constraints rather than pollen percentages for each individual taxon. The distribution of pollen taxa into plant functional types (PFTs) is aimed to reflect the vegetation in terms of biomes which have a wider distribution than a species. The climatic variables are then calibrated on these PFTs using an artificial neural network technique. The use of PFTs allowed us to deal with situations where pollen assemblages have only partial modern analogs. The method is applied to the glacial steppic vegetation in Europe, using 15 pollen records. North of the Pyrenees–Alps line, the reconstructed temperatures were lower than today: −30 ± 10°C for the temperature of the coldest month ( Tc) and −12 ± 3°C for the annual mean ( Tann). South of that line, Tc and Tann anomalies were respectively, −15 ± 5°C and −10 ± 5°C. The available moisture index and annual precipitation were also lower than present: −60 ± 20% north of Mediterranean Sea, (−800 ± 100 mm for precipitation). In Italy and Greece, the available moisture was 20% lower, with a precipitation anomaly of ca. −600 ± 200 mm. Southward, the moisture index was close to that at present (±20%), and precipitation was lower (−300 ± 300 mm).

scholarly journals Palaeoecological aspects of an Ukrainian Upper Holocene chernozem

2020 ◽  
Vol 31 (2) ◽  
pp. 59-64
Author(s):  
J. M. Recio Espejo ◽  
O. V. Kotovych ◽  
F. Díaz del Olmo ◽  
V. A. Gorban ◽  
R. Cámara Artigas ◽  
...  
Keyword(s):  
Environmental Changes ◽  
Organic Carbon Content ◽  
Glacial Period ◽  
Pollen Data ◽  
Last Glacial Period ◽  
Pollen Types ◽  
Parental Material ◽  
Dark Color ◽  
Sedimentation Processes ◽  
The Last Glacial

A physicochemical, palynological and chronological analysis of a soil profile corresponding to a Haplic Chernozem (FAO, 2015) developed in the Ukrainian steppe allow the interpretation of recent environmental changes that have conditioned its formation. Uniformed under the blackening process, its surface horizon dark color contrasts with yellowish color loessic parental material; it is decarbonated and the organic carbon content on the surface is 2.24%.The texture is silty in surface but sandy in lower horizon denoting a clear wind selection and an energy change in aeolian sedimentation processes. The clays present similar values ​​in the three analyzed horizons. The presence of two discontinuities in the profile has made it possible to distinguish a very sandy blackened horizon of 2500 +/- 25cal BP chronologies from another silty surface and black chromas of age 1336–1256 cal BP. A total of fifteen pollen types have been identified; superficial horizon (A11) has a high presence of pollen of the Amaranthaceae type, the Poaceae are the most abundant and Quercus gender is identified. The sandy horizon (2A/B) shows Poaceas, Pinus, and Oleaceas presence together pollen of Rosaceas type (14%). Pollen data reveal vegetative changes in the three horizons with the presence of even non-existent species today, linked both to recent anthropic-climatic and holocene-type changes on a millennial scale since the last glacial period.

Improving age models for abrupt climate changes during the last glacial by pattern recognition

2020 ◽  
Author(s):  
Mark Turner ◽  
Sandy Harrison
Keyword(s):  
Pattern Recognition ◽  
Goodness Of Fit ◽  
Climate Changes ◽  
Global Climate ◽  
Glacial Period ◽  
Last Glacial Period ◽  
Last Glacial ◽  
Global Climate Changes ◽  
Pollen Records ◽  
The Last Glacial

<p>Quaternary records provide an opportunity to examine how regional climates and vegetation reflect global climate changes comparable in magnitude and velocity to those expected during the 21st century.  The Dansgaard-Oeschger (D-O) cycles of the last glacial period provide the best documented examples of such rapid climate warmings (Greenland interstadials, GIs). However, the age models of pollen records that document regional responses to D-O events are, in general, poorly constrained beyond the radiocarbon timescale. Here we use a pattern-recognition approach, based on matching oscillations in palaeoclimate records to a template of D-O events seen in the Greenland record, to provide better constrained age models. We create a series of templates of Greenland Interstadials (GIs) and compare these to a normalised and detrended time series from a target record using a sliding window and measuring goodness-of-fit using Euclidian distance. We show that this approach can identify D-O events in well-dated records, including reproducing the Greenland record itself. We then apply this approach to the less well-constrained pollen records from the last glacial period from southern Europe. The re-aligned age models permit a more robust comparison of the reconstructed vegetation and climate changes through time and across sites, allowing for regional differences in the response to individual GIs to be identified.</p>

scholarly journals Post-depositional manganese mobilization during the last glacial period in sediments of the eastern Clarion-Clipperton Zone, Pacific Ocean

2020 ◽  
Vol 532 ◽  
pp. 116012 ◽  
Author(s):  
Jessica B. Volz ◽  
Bo Liu ◽  
Male Köster ◽  
Susann Henkel ◽  
Andrea Koschinsky ◽  
...  
Keyword(s):  
Pacific Ocean ◽  
Glacial Period ◽  
Last Glacial Period ◽  
Last Glacial ◽  
The Last Glacial
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