scholarly journals Vegetation Changes in Southeastern Siberia During the Late Pleistocene and the Holocene

2021 ◽  
Vol 9 ◽  
Author(s):  
Jérémy Courtin ◽  
Andrei A. Andreev ◽  
Elena Raschke ◽  
Sarah Bala ◽  
Boris K. Biskaborn ◽  
...  
Keyword(s):  
Late Pleistocene ◽  
Vegetation Changes ◽  
Terrestrial Vegetation ◽  
Vegetation Composition ◽  
The Holocene ◽  
Taxa Richness ◽  
Southeastern Siberia ◽  
Tundra Vegetation ◽  
Species Area ◽  
Keystone Herbivore

Relationships between climate, species composition, and species richness are of particular importance for understanding how boreal ecosystems will respond to ongoing climate change. This study aims to reconstruct changes in terrestrial vegetation composition and taxa richness during the glacial Late Pleistocene and the interglacial Holocene in the sparsely studied southeastern Yakutia (Siberia) by using pollen and sedimentary ancient DNA (sedaDNA) records. Pollen and sedaDNA metabarcoding data using the trnL g and h markers were obtained from a sediment core from Lake Bolshoe Toko. Both proxies were used to reconstruct the vegetation composition, while metabarcoding data were also used to investigate changes in plant taxa richness. The combination of pollen and sedaDNA approaches allows a robust estimation of regional and local past terrestrial vegetation composition around Bolshoe Toko during the last ∼35,000 years. Both proxies suggest that during the Late Pleistocene, southeastern Siberia was covered by open steppe-tundra dominated by graminoids and forbs with patches of shrubs, confirming that steppe-tundra extended far south in Siberia. Both proxies show disturbance at the transition between the Late Pleistocene and the Holocene suggesting a period with scarce vegetation, changes in the hydrochemical conditions in the lake, and in sedimentation rates. Both proxies document drastic changes in vegetation composition in the early Holocene with an increased number of trees and shrubs and the appearance of new tree taxa in the lake’s vicinity. The sedaDNA method suggests that the Late Pleistocene steppe-tundra vegetation supported a higher number of terrestrial plant taxa than the forested Holocene. This could be explained, for example, by the “keystone herbivore” hypothesis, which suggests that Late Pleistocene megaherbivores were able to maintain a high plant diversity. This is discussed in the light of the data with the broadly accepted species-area hypothesis as steppe-tundra covered such an extensive area during the Late Pleistocene.

Paleoenvironmental proxy records from Lake Hovsgol, Mongolia, and a synthesis of Holocene climate change in the Lake Baikal watershed

2007 ◽  
Vol 68 (1) ◽  
pp. 2-17 ◽  
Author(s):  
Alexander A. Prokopenko ◽  
Galina K. Khursevich ◽  
Elena V. Bezrukova ◽  
Mikhail I. Kuzmin ◽  
Xavier Boes ◽  
...  
Keyword(s):  
Lake Baikal ◽  
Asian Summer Monsoon ◽  
Vegetation Changes ◽  
Terrestrial Vegetation ◽  
The Holocene ◽  
Proxy Records ◽  
Lake Hovsgol ◽  
Soil Temperatures ◽  
Paleoenvironmental Evolution ◽  
Paleoclimate Records

AbstractHere we discuss paleoenvironmental evolution in the Baikal region during the Holocene using new records of aquatic (diatom) and terrestrial vegetation changes from Hovsgol, Mongolia's largest and deepest lake. We reconcile previous contradictory Baikal timescales by constraining reservoir corrections of AMS dates on bulk sedimentary organic carbon. Synthesis of the Holocene records in the Baikal watershed reveals a northward progression in landscape/vegetation changes and an anti-phase behavior of diatom and biogenic silica proxies in neighboring rift lakes. In Lake Baikal, these proxies appear to be responsive to annual temperature increases after 6 ka, whereas in Lake Hovsgol they respond to higher precipitation/runoff from 11 to 7 ka. Unlike around Lake Baikal, warmer summers between 6 and 3.5 ka resulted in the decline, not expansion, of forest vegetation around Lake Hovsgol, apparently as a result of higher soil temperatures and lower moisture availability. The regional climatic proxy data are consistent with a series of 500-yr time slice Holocene GCM simulations for continental Eurasia. Our results allow reevaluation of the concepts of ‘the Holocene optimum’ and a ‘maximum of the Asian summer monsoon’, as applied to paleoclimate records from continental Asia.

Vegetation changes from the late Pleistocene through the Holocene from three areas of archaeological significance in Thailand

2004 ◽  
Vol 113 (1) ◽  
pp. 111-132 ◽  
Author(s):  
Joyce C. White ◽  
Daniel Penny ◽  
Lisa Kealhofer ◽  
Bernard Maloney
Keyword(s):  
Late Pleistocene ◽  
Vegetation Changes ◽  
The Holocene

Vegetation dynamics of the eastern Mediterranean region during the Holocene

2021 ◽  
Author(s):  
Esmeralda Cruz-Silva ◽  
Sandy P. Harrison ◽  
Elena Marinova ◽  
I. Colin Prentice
Keyword(s):  
Mediterranean Region ◽  
Likelihood Function ◽  
Eastern Mediterranean ◽  
Regional Scale ◽  
Eastern Mediterranean Region ◽  
Similarity Index ◽  
Vegetation Changes ◽  
Human Occupation ◽  
The Holocene ◽  
Atmospheric Circulation Patterns

<p>The circum-Mediterranean region is characterized by high climatic diversity derived from its orographic heterogeneity and the influence of global marine and atmospheric circulation patterns. The region also has a long and dynamic history of human occupation dating back to ~ 8000 years BP.  The complexity of this area is a challenge for reconstructing the dynamics of the vegetation through the Holocene. Rule-based approaches to reconstructing changing vegetation patterns through time are insufficient as they require the imposition of subjective boundaries between biomes and can be affected by known biases in pollen representation.  We have developed and tested a new method that characterises biomes as a function of observed pollen assemblages based on a similarity index, conceptually related to the likelihood function, which takes account of within-biome variability in taxon abundances. We use 1181 modern pollen samples from the EMBSeCBIO database and assign these samples to biomes as represented in a map of potential natural vegetation that was developed using machine learning. The method was applied down-core to reconstruct past vegetation changes. Preliminary results show that this new methodology produces more accurate biome assignments under modern conditions (<80% accuracy) and more stable down-core reconstructions, apparently reducing the "flickering switch" problem found when using the traditional biomisation method for this purpose. Climate-induced vegetation changes are observable on a sub-regional scale in the Eastern Mediterranean through the Holocene. Most of the records show a change from humid to more arid biomes between 4000 and 3000 years BP. However, they are distinct subregional patterns in the expression and timing of wetter conditions during the Holocene. Mountain regions appear to show more muted changes during the Holocene, although there are biome shifts everywhere across the Pleistocene-Holocene transition.</p>

scholarly journals The Ice-Rich Permafrost Sequences as a Paleoenvironmental Archive for the Kara Sea Region (Western Arctic)

2021 ◽  
Vol 9 ◽  
Author(s):  
I. D. Streletskaya ◽  
A. A. Pismeniuk ◽  
A. A. Vasiliev ◽  
E. A. Gusev ◽  
G. E. Oblogov ◽  
...  
Keyword(s):  
Late Pleistocene ◽  
Marine Sediments ◽  
Isotope Composition ◽  
Kara Sea ◽  
Coastal Sediments ◽  
Organic Carbon Content ◽  
Ground Ice ◽  
Geochemical Composition ◽  
The Holocene ◽  
Mis 3

The Kara Sea coast and part of the shelf are characterized by wide presence of the ice-rich permafrost sequences containing massive tabular ground ice (MTGI) and ice wedges (IW). The investigations of distribution, morphology and isotopic composition of MTGI and IW allows paleoenvironmental reconstructions for Late Pleistocene and Holocene period in the Kara Sea Region. This work summarizes result of long-term research of ice-rich permafrost at eight key sites located in the Yamal, Gydan, Taimyr Peninsulas, and Sibiryakov Island. We identified several types of ground ice in the coastal sediments and summarized data on their isotopic and geochemical composition, and methane content. We summarized the available data on particle size distribution, ice chemical composition, including organic carbon content, and age of the enclosing ice sediments. The results show that Quaternary sediments of the region accumulated during MIS 5 – MIS 1 and generally consisted of two main stratigraphic parts. Ice-rich polygenetic continental sediments with syngenetic and epigenetic IW represent the upper part of geological sections (10–15 m). The IW formed in two stages: in the Late Pleistocene (MIS 3 – MIS 2) and in the Holocene cold periods. Oxygen isotope composition of IW formed during MIS 3 – MIS 2 is on average 6‰ lower than that of the Holocene IW. The saline clay with rare sand layers of the lower part of geological sections, formed in marine and shallow shelf anaerobic conditions. MTGI present in the lower part of the sections. The MTGI formed under epigenetic freezing of marine sediments immediately after sea regression and syngenetic freezing of marine sediments in the tidal zone and in the conditions of shallow sea.

Holocene history of boreal forest landscapes of the Central European Russia

2021 ◽  
Author(s):  
Vladimir Belyaev ◽  
Ilya Shorkunov ◽  
Katerina Garankina ◽  
Nikita Mergelov ◽  
Yulia Shishkina ◽  
...  
Keyword(s):  
Boreal Forest ◽  
Late Pleistocene ◽  
Gully Erosion ◽  
European Russia ◽  
Empirical Modeling ◽  
Snowmelt Runoff ◽  
Central European ◽  
The Holocene ◽  
High Magnitude ◽  
Late Pleistocene To Holocene

<p>Recent detailed investigations of landforms, soils and surface deposits of the Borisoglebsk Upland northeastern slope within the Nero Lake basin (Central European Russia, Yaroslavl Region) allowed deciphering co-evolution of the major landscape components of the case study area since the Late Pleistocene. The Late Pleistocene to Holocene transition in the gully network was represented by relatively short but high-magnitude (up to 12 m) incision phase followed by significant infill till 6.5 ka. Absence of the well-developed early Holocene paleosols in the studied sections and cores suggests dominantly negative sediment budget. There is so far limited evidence of sedimentation over the first half of the Holocene. Discontinuous deposition with certain interruptions (but without distinct buried soil formation) occurred only within closed depressions and on gully fans. The second part of the Holocene prior to the widespread human settlement left more substantial traces in soil and sediment record. Despite the common perception of the pristine boreal forest landscapes to be geomorphologically stable due to erosion-protective role of woodland vegetation, several phases of dramatically increased soil and gully erosion rates have been identified. It is identified in soil bodies and sediments, both at locations dominated by denudation (evidences of multiple topsoil truncation in Atlantic and Subatlantic) and at zones of alternating incision and infill of small linear erosion features. Such extremes were most likely associated with combination of several triggers including natural forest fires and high-magnitude rainfall or snowmelt runoff events. There are several <sup>14</sup>C dated layers of pyrogenic charcoal indicating pre-anthropogenic wildfire-induced incision and infill cycles during the middle and late Holocene.</p><p>The last phases of increased hillslope and fluvial activity within the study area can be related to increased human interference, starting from about 1600-900 years ago. The onset of cut-and-burn cultivation is independently established from available archeological evidences, dating of cut and burnt tree logs remnants, organic material buried by agrogenic colluvium and gully fans. Latest period of intensive gully growth can most likely be attributed to the XIX<sup>th</sup> Century land tenure reform, when most of the study area gullies experienced significant linear growth, bottom incisions and appearance of several new gully branches. The most recent trend of soil and gully erosion has been evaluated by <sup>137</sup>Cs sediment tracing, soil empirical modeling and comparison of historical and modern maps, airborne photos and satellite images. Rates of soil redistribution on slopes decreased significantly over the last several decades due to combination of natural and anthropogenic impacts: 1) decreased spring snowmelt runoff caused mainly by generally lowered thickness of seasonally frozen topsoil layer; 2) arable land abandonment or shift from row crops and cereals to perennial grass-dominated crop rotations in the post-Soviet period. In addition, local short-term (from several years to within-year) cycles of relatively low-magnitude (not exceeding ±1 m range) incision and infill in gullies are often triggered by biogenic activities, namely beaver dam constructions and breaches and local log jams.</p><p>The study is supported by the Russian Science Foundation (Project No. 19-77-10061) and Russian Foundation for Basic Research (Project No. 19-29-05238).</p>

A Good Place to Live: Plants and People at the Santa Elina Rock Shelter (Central Brazil) from Late Pleistocene to the Holocene

2020 ◽  
Vol 31 (2) ◽  
pp. 273-291
Author(s):  
Rita Scheel-Ybert ◽  
Caroline Bachelet
Keyword(s):  
Late Pleistocene ◽  
Late Holocene ◽  
Vegetation Changes ◽  
Vegetation Types ◽  
Rock Shelter ◽  
Good Place ◽  
Central Brazil ◽  
Cultural Preference ◽  
Vegetation And Climate ◽  
Over Time

The Santa Elina rock shelter (Central Brazil) was recurrently occupied from the Late Pleistocene to the Late Holocene. We compare sets of previously published anthracological analyses with new data to reconstruct the landscape, vegetation, and climate over the several thousand years of occupation, providing information on firewood management from about 27,000 to about 1500 cal BP. Laboratory analyses followed standard anthracological procedures. We identified 34 botanical families and 84 genera in a sample of almost 5,000 charcoal pieces. The Leguminosae family dominates the assemblage, followed by Anacardiaceae, Bignoniaceae, Rubiaceae, Euphorbiaceae, and Sapotaceae. The area surrounding the shelter was forested throughout the studied period. The local landscape was formed, as it is today, by a mosaic of vegetation types that include forest formations and open cerrado. Some regional vegetation changes may have occurred over time. Our data corroborate the practice of opportunistic firewood gathering in all periods of site occupation, despite a possible cultural preference for some taxa. The very long occupation of Santa Elina may be due not only to its attractiveness as a rock shelter but also to the continuously forested vegetation around it. It was a good place to live.

Loess–paleosol carbonate clumped isotope record of late Pleistocene–Holocene climate change in the Palouse region, Washington State, USA

2018 ◽  
Vol 90 (2) ◽  
pp. 331-347 ◽  
Author(s):  
Alex R. Lechler ◽  
Katharine W. Huntington ◽  
Daniel O. Breecker ◽  
Mark R. Sweeney ◽  
Andrew J. Schauer
Keyword(s):  
Pacific Northwest ◽  
Late Pleistocene ◽  
Climate Model ◽  
The United States ◽  
Soil Conditions ◽  
Isotopic Study ◽  
The Holocene ◽  
Last Glacial ◽  
Carbonate Formation ◽  
Clumped Isotope

AbstractThe Channeled Scabland–Palouse region of the Pacific Northwest (PNW) of the United States preserves geomorphic and pedosedimentary records that inform understanding of late Pleistocene–Holocene paleoclimate change in a region proximal to the last glacial period Cordilleran Ice Sheet. We present a clumped (Δ47) and conventional (δ18O, δ13C) isotopic study of Palouse loess–paleosol carbonates in combination with carbonate radiocarbon (14C) dating to provide new measures of regional late–last glacial (~31–20 cal ka BP) and Holocene soil conditions. Average clumped isotope temperatures (T(Δ47)) for last glacial Palouse loess–paleosol carbonates (9±4°C) are significantly lower than those for Holocene-aged carbonates (T(Δ47)=18±2°C) in study sections. Calculated soil water δ18OVSMOWvalues (−16±2‰) for last glacial carbonates are also offset relative to those for Holocene-aged samples (−11±1‰), whereas calculated soil CO2δ13CVPDBvalues are similar for the Holocene (−16.9±0.2‰) and late–last glacial (−16.7±1.1‰) periods. Together, these paleoclimate metrics indicate late–last glacial conditions of pedogenic carbonate formation in the C3grassland soils of the Palouse were measurably colder (9±5°C) than during the Holocene and potentially reflect a more arid last glacial paleoclimate across the Palouse, findings in agreement with previous proxy studies and climate model simulations for the region.

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