Late-Holocene palaeoenvironmental reconstruction from a lake in the Amazon Rainforest-Tropical Savanna (Cerrado) boundary in Brazil using a multi-proxy approach

The Holocene ◽  
2021 ◽  
pp. 095968362110190
Author(s):  
Kury Milena Souza ◽  
Moreira Luciane Silva ◽  
Cordeiro Renato Campello ◽  
Sifeddine Abdelfettah ◽  
Turcq Bruno ◽  
...  
Keyword(s):  
Late Holocene ◽  
Amazon Region ◽  
Amazon Rainforest ◽  
Oxbow Lake ◽  
Tropical Savanna ◽  
Sedimentary Process ◽  
Climatic Fluctuations ◽  
Climate Conditions ◽  
Depositional Processes ◽  
Lake Formation

As an ecotone, the region between the Amazon Rainforest and Tropical Savanna (Cerrado) biomes is, by definition, more susceptible to climate change. Therefore, understanding palaeoenvironmental dynamics is essential to address the future responses of such transition areas to climatic fluctuations. In this context, we present a new sediment record for the Late-Holocene retrieved from Barro-Preto, currently an oxbow lake located in an ecotone at the southern Brazilian Amazon border. Our multi-proxy data include carbon and nitrogen isotopes, as well as bulk TOC, chlorophyll derivatives, grain-size and microcharcoal analyses, all anchored on a radiocarbon-dated chronology. The sedimentary process recorded at the Barro-Preto Lake responded to both local and regional climate dynamics. It was influenced by river excursions associated to local responses to precipitation changes by the activation of the palaeochannel connecting the main-stem river and the Barro-Preto lake. This activation was evidenced by the presence of different colour lithology laminations accompanied by coarser sediments and also by climate conditions known to influence the Amazon region. Depositional processes linked to lake dynamics and different oxbow lake cycle stages were also important to explain the changes verified in the Barro-Preto record, endorsing the use of this lake formation for palaeoclimatic reconstructions. The record indicated a rising humidity trend, reflected by a progressive increase in lacustrine productivity, in accordance to other studies carried out in the Amazon region concerning the Late-Holocene, associated with a more southward displacement of the Intertropical Convergence Zone. Despite this rising humidity trend, dry episodic events during the Late-Holocene were evidenced by charcoal data, also coherent with regional Amazon studies, albeit exhibiting increased intensity, suggesting that the transitional nature of the environment might have influenced susceptibility to fires.

Furuncular Myiasis by Dermatobia hominis (Diptera: Oestridae) in Wild Jaguars in the Amazon Rainforest

2021 ◽  
Author(s):  
Matheus Mickael Mota Soares ◽  
Luana Machado Barros ◽  
Daniela Aparecida Savariz Bôlla ◽  
Marlus Queiroz Almeida ◽  
Diego da Costa Souza ◽  
...  
Keyword(s):  
Brazilian Amazon ◽  
First Record ◽  
Amazon Region ◽  
Amazon Rainforest ◽  
Panthera Onca ◽  
Dermatobia Hominis ◽  
Furuncular Myiasis

Abstract Two individuals of the jaguar, Panthera onca (L.), were captured near the municipality of Presidente Figueiredo, Brazilian Amazon, during the years of 2017 and 2018. The jaguars presented furuncular myiasis caused by the human botfly Dermatobia hominis (L.) on the rear thighs and tail. This is the first record of infestation of D. hominis in P. onca in the Amazon region.

Human occupation strategies and related environmental-climate during the middle and late Holocene in central Pampas of Argentina

The Holocene ◽  
2018 ◽  
Vol 29 (2) ◽  
pp. 244-261 ◽  
Author(s):  
Pablo G Messineo ◽  
Marcela S Tonello ◽  
Silvina Stutz ◽  
Alfonsina Tripaldi ◽  
Nahuel Scheifler ◽  
...  
Keyword(s):  
Late Holocene ◽  
Specific Activity ◽  
Climatic Conditions ◽  
Hard Material ◽  
Human Occupation ◽  
Climate Conditions ◽  
Lithic Assemblage ◽  
Depositional Rate ◽  
Archeological Site ◽  
Middle And Late Holocene

The main objective of this work is to generate and integrate interpretations of human occupation strategies and inferences of the environmental-climatic conditions in the central Pampas during the middle and late Holocene. We present a novel archeological–geological–paleoecological analysis in the area of the Cabeza de Buey lake, placed in an aeolian landscape. During the middle Holocene, two events of human occupations were recognized at Laguna Cabeza de Buey 2 archeological site. Both events present a small amount of lithic materials, a low diversity of tools and activities developed with them (principally hard material), and the hunting and primary processing of artiodactyls. These evidences suggest a locus of specific activity associated with an ephemeral human settlement under climate conditions drier than present and the presence of small, brackish, and shallow water bodies. For the late late Holocene, the hunter-gatherer occupation has a higher depositional rate of lithic assemblage, stones with diverse origins, presence of pottery fragments, a great lithic tool diversity, knapping techniques, and activities developed with these tools (processing wood, bone, hide, non-woody plant, and soft material). These evidences reveal an occupation with a higher degree of recurrence represented by a locus of multiple activities associated with a more stable landscape, such as an environment of dunes fixed by grass vegetation, and the establishment of a permanent water body. The different environmental characteristics for the middle and late Holocene in this area promoted that human groups develop two different patterns of mobility, settlement and use of space.

scholarly journals Impact of Climate on Vegetation Change in a Mountain Grassland – Succession and Fluctuation

2014 ◽  
Vol 42 (2) ◽  
pp. 347-356 ◽  
Author(s):  
Florin PĂCURAR ◽  
Ioan ROTAR ◽  
Albert REIF ◽  
Roxana VIDICAN ◽  
Vlad STOIAN ◽  
...  
Keyword(s):  
Vegetation Change ◽  
Compositional Data ◽  
Classification Tree ◽  
Vegetation Period ◽  
Early Years ◽  
Permanent Plots ◽  
Climate Variables ◽  
Vegetation Composition ◽  
Climatic Fluctuations ◽  
Climate Conditions

Traditionally managed Central European mountain grasslands have high nature conservation value because of their high species diversity. Whether these grasslands and their diversity can be preserved will depend on many factors, including how plant species composition responds to changes in climate conditions. To differentiate between fluctuations and directional succession in the herbaceous layer composition of a Romanian Festuca rubra L. and Agrostis capillaris L. grassland in Apuseni and whether any compositional changes can be related to climate. The vegetation of permanent plots was recorded annually between 2004 and 2012. Temperature and precipitation were measured by an automatic weather station at the study site. Cluster analysis, Indicator Species Analysis and the co-dominance ratio between F. rubra L.- A. capillaris were analysed. The compositional data was related to the climate variables. Thresholds of relevant climate variables differentiating between clusters of plots with similar vegetation composition were determined using classification tree methods. The vegetation composition in our plots within the years 2004, 2005 and 2008 were different from each other. From 2004 to 2006 directional succession could be identified; however the major patterns to emerge were fluctuations which occurred over the whole study period. Compositional shifts included A. capillaris L. and F. rubra L exchanging co-dominance with each other. The most important variables differentiating clusters were temperature during the dormant and vegetation periods and water balance during the vegetation period. It can be concluded that compositional shifts among years were largely a consequence of year to year climatic fluctuations; however, there is some evidence for a directional shift during the early years of the study./span>

Ficção e fricção: imagens da Amazónia no cinema internacional

2021 ◽  
Author(s):  
Fabiana Wielewicki ◽  
Guy Amado
Keyword(s):  
Amazon Region ◽  
Amazon Rainforest ◽  
Horror Film ◽  
One Dimensional ◽  
The Real ◽  
Western Countries ◽  
International Circulation ◽  
Feature Films ◽  
Film Productions

Explored by foreign travellers in different periods, the Amazon rainforest has long dwelt in the imagery of western countries. This trend is naturally extended to its numerous representations in cinema, often in a stereotyped perspective, full of clichés that respond to entertainment demands or to superficial foreign curiosity. This paper proposes to analyse its presence in some feature films produced mostly (but not only) in Hollywood along the last five decades. It aims at investigating how, in mainstream cinema, the features and characteristics that are supposedly typical of the region are shown, along with the demands of the respective film narratives, and at pinpointing the inevitable mismatches that emerge when facing the complexity of the ‘continent’ that effectively constitutes the region. In genres that run from adventure to comedy, fantasy or horror, film productions have set their plots there – partially, at least, and artificially or effectively – with varying approaches and degrees of depth to the region’s peculiarities. The choice of productions with so-called commercial appeal is due to such films having greater reach and international circulation. Thus their features are interesting for their capacity of spreading such imaginary, often with a shallow or distorted bias. The present is not a precise, socio-anthropological comparison between the ‘real’ Amazon region and that which is shown on the screens as a lost tropical paradise or a ‘green inferno’, for instance, but rather to point out how the logics of entertaining may assimilate a complex and multifaceted imaginary and present it in a simplistic, schematic, one-dimensional way.

Multi-proxy studies of the Late Glacial fluvio-aeolian succession in the type site Mierzyn, central Poland 

2021 ◽  
Author(s):  
Moska Piotr ◽  
Sokołowski Robert ◽  
Jary Zdzisław ◽  
Zieliński Paweł ◽  
Raczyk Jerzy ◽  
...  
Keyword(s):  
Western Europe ◽  
Late Glacial ◽  
Luminescence Dating ◽  
Climate Conditions ◽  
Central Poland ◽  
Depositional Processes ◽  
Dating Methods ◽  
Absolute Dating ◽  
Absolute Age ◽  
Pedogenic Processes

<p>Multi-proxy studies (including sedimentological, pedological, radiocarbon and optically stimulated luminescence dating methods) were used to establish origin and chronology of depositional processes in the type section Mierzyn, central Poland. The investigated key site is located in the extraglacial zone of the Last Glaciation, ca. 130 km to the south from the Last Glacial Maximum in the Luciąża river valley area. In the studied profile (16 m thick) two lithofacial complexes were identified. The lower, fluvio-aeolian complex consists of silty-sandy sediments (1.6 m) deposited. The final phase of fluvio-aeolian deposition is expressed by initial pedogenic processes. Above is located aeolian complex (13 m of thickness). Three aeolian units are separated by two palaeosols.</p><p>To establish stratigraphic framework of depositional and pedogenic processes, four samples for radiocarbon dating from palaeosols and twelve samples for OSL dating from sandy units were collected. The obtained results reveal very good agreement of both absolute dating methods. It led to reconstruct chronology of main palaeoenvironmental changes. The fluvio-aeolian complex and the lowermost part of aeolian complex (below the lower palaeosol) were deposited in the Oldest Dryas in relatively cool and dry climate conditions. The amelioration of climate in the Bølling interstadial caused development of pedogenic processes expressed by 0.3 m thick palaeosol. Main part of aeolian complex (10 m of thickness) was deposited in the Older Dryas. The upper palaeosol developed in the Allerød interstadial as a result of the next amelioration of the climate. During the Younger Dryas was deposited the uppermost part of aeolian complex.</p><p>Classic development of fluvial to- aeolian succession in the Mierzyn site as well as detailed chronology based on two independent absolute age methods reveal that it can be treated as stratotype for the Late Glacial and correlated with other type sections in the Central and Western Europe.</p><p><strong>Ackowledgments</strong></p><p>Presented results were obtained with support of Polish National Science Centre, contract number 2018/30/E/ST10/00616.</p><p> </p>

Stratigraphy and sedimentary process in a closed-basin lake in Central Italy during the Anthropocene

2021 ◽  
Author(s):  
Paola Gravina ◽  
Beatrice Moroni ◽  
Riccardo Vivani ◽  
Alessandro Ludovisi ◽  
Roberta Selvaggi ◽  
...  
Keyword(s):  
High Resolution ◽  
Water Level ◽  
Lake Sediments ◽  
Biological Effects ◽  
Central Italy ◽  
Geochemical Data ◽  
Climate Variations ◽  
Sedimentary Process ◽  
Climatic Fluctuations ◽  
Precipitation Processes

<p>Shallow and closed lakes are affected by meteorological and climate variations and are especially sensitive to the change in their hydrological balance. In central Italy, there is the fourth-largest lake of the country, the Trasimeno Lake, whose water level has undergone various fluctuations over the centuries with alternation of flood and drought periods because of its shallow depth and the absence of natural outflows [1].</p><p>Sediment archives are used as information records to study chemical, physical, and biological environmental variations and changes in the hydrological budget driven by climatic fluctuations, but this is particularly complicated in shallow lakes due to the multiple perturbative phenomena. A robust study depends on the ability to obtain valid high-resolution geochemical data from lake sediments.</p><p>We conducted high-resolution geochemical analysis on three sediment cores about 1 meter long each, collected in Lake Trasimeno. We sectioned at 1  or 2 cm interval, which provided a detailed characterization of the significant changes in lacustrine processes that occurred in the basin during the Anthropocene (~last 150 years) [2], combining quantitative chemical (ICP-OES) and semi-quantitative (XRD and SEM) investigations. Geochemical variables are used as paleolimnological proxies to reconstruct past lake events that occurred within the water column. In particular, we report the study of the endogenic precipitates characteristic of the Trasimeno sediments, whose precipitation processes have been influenced by water fluctuations and anthropogenic impacts.</p><p>Given the strong presence of water fluctuations, the investigation period was divided into three distinct phases related to the lake's hydrometric state and characterized by sedimentary compounds of different nature. The endogenic carbonate compounds of calcite (commonly present in the Trasimeno sediments) contain a different Mg percentage during the different hydrometric phases. The lake sediments are particularly rich in Mg-calcite due to both water level changes and biological effects. Moreover, co-precipitation of non-crystalline Ca-P compounds (e.g., apatite type) has been detected during a hydrometric phase characterized by high microorganisms activity. Precipitation processes were triggered in Trasimeno by the growth of nutrient discharge into the lake (since the 1970s) and are currently studied for their importance in controlling eutrophication phenomena.</p><p>In conclusion, our findings show that rapid lake responses to water fluctuations and climate variations were transcribed within the sedimentary stratigraphic archives, which underlines their value and high quality in paleoenvironmental and paleohydrological reconstruction.</p><p>References:</p><p>[1] Frondini, Dragoni, Morgantini, Donnini, Cardellini, Caliro, Melillo, and Chiodini (2019). An En-dorheic Lake in a Changing Climate: Geochemical Investigations at Lake Trasimeno (Italy).Water, 11(7):1319.</p><p> [2] Gaino, E., Scoccia, F., Piersanti, S., Rebora, M., Bellucci, L. G., and Ludovisi, A. (2012). Spiculerecords of Ephydatia fluviatilis as a proxy for hydrological and environmental changes inthe shallow Lake Trasimeno (Umbria, Italy). Hydrobiologia, 679(1):139–153.</p>

Neanderthal landscapes and subsistence strategies during late Quaternary glacial-interglacial periods: insights from the avian assemblages of Grotta del Cavallo (Apulia, Southern Italy)

2021 ◽  
Author(s):  
Lisa Carrera ◽  
Daniele Scarponi ◽  
Fabio Martini ◽  
Lucia Sarti ◽  
Marco Pavia
Keyword(s):  
Southern Italy ◽  
Late Quaternary ◽  
Sediment Accumulation ◽  
Sampling Effort ◽  
Paleolithic Site ◽  
Climate Conditions ◽  
Bird Assemblages ◽  
Depositional Processes ◽  
Feeding Activities ◽  
The Rich

<p>Grotta del Cavallo, a well-known Paleolithic site in Southern Italy (Nardò, Apulia), preserves one of the most important Italian Middle Paleolithic sequences. Its stratigraphic succession records the presence of Neanderthals from Marine Isotope Stage (MIS) 7 to 3, providing substantial insights on their lifeways. Here we present the taxonomic and taphonomic analysis of the bird assemblages associated to Neanderthal occupation. The rich avifaunal assemblages allowed paleoenvironmental and paleoclimatic reconstructions, noticeably improving the reconstruction of the landscape that was exploited by Neanderthals throughout the last glacial-interglacial cycles. Based on the bird taxa identified in the assemblages, Grotta del Cavallo was mainly surrounded by extensive grasslands and shrublands, with scattered open woodland and rocky outcrops, during MIS 7, 6 and 3. The coastal plain, that is currently underwater due to Holocene relative sea-level rise, hosted wetlands in the cooler periods, when it was exposed. In the cool-temperate climatic phase attributed to MIS 3, bird taxa of water and wet environments proportionally increased, as well as coverage-based rarefied richness values. This is possibly due to the expansion of wetland areas, linked to more humid conditions, or to the shorter distance of the wetland settings from the cave, compared to MIS 6 (glacial period). A consequent higher heterogeneity of the landscape is retained to drive the increased richness. The sampling effort allowed to retrieve bird taxa that provided significant paleoclimatic insights, such as Branta leucopsis, an arctic breeder, and other species currently spread at higher altitudes, that reinforce previously obtained geochemical derived inference of climate conditions cooler than the present ones. The bird assemblages also provided the first occurrence ever of Larus genei, the first Italian occurrence of Emberiza calandra, the oldest Italian occurrence of Podiceps nigricollis, and the occurrence of Sylvia communis (a species rarely retrieved in the fossil record). Ordination analyses of the bird dataset detected the drivers of taphonomic degradation and the agents responsible for the accumulation of the avian bones: modifications are mainly due to physical sin- and post-depositional processes, whereas accumulation is mainly attributed to short-range physical processes of sediment accumulation, feeding activities of nocturnal raptors and, to a lesser extent, human activities. In detail, traces found on a few bones suggest that Neanderthals introduced some of the birds in the cave with alimentary purposes, providing the earliest Italian evidence of bird exploitation ever.</p>

scholarly journals Late Holocene droughts and cave ice harvesting by Ancestral Puebloans

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Bogdan P. Onac ◽  
Steven M. Baumann ◽  
Dylan S. Parmenter ◽  
Eric Weaver ◽  
Tiberiu B. Sava
Keyword(s):  
Climate Change ◽  
New Mexico ◽  
Native Americans ◽  
Water Availability ◽  
Late Holocene ◽  
Human Environment ◽  
Climate Conditions ◽  
Ancestral Puebloan ◽  
Ancestral Puebloans ◽  
Marginal Environment

AbstractWater availability for Native Americans in the southwestern United States during periods of prolonged droughts is poorly understood as regional hydroclimate records are scant or contradicting. Here, we show that radiocarbon-dated charcoal recovered from an ice deposit accumulated in Cave 29, western New Mexico, provide unambiguous evidence for five drought events that impacted the Ancestral Puebloan society between ~ AD 150 and 950. The presence of abundant charred material in this cave indicates that they periodically obtained drinking water by using fire to melt cave ice, and sheds light on one of many human–environment interactions in the Southwest in a context when climate change forced growing Ancestral Puebloan populations to exploit water resources in unexpected locations. The melting of cave ice under current climate conditions is both uncovering and threatening a fragile source of paleoenvironmental and archaeological evidence of human adaptations to a seemingly marginal environment.

scholarly journals A Gas-Emission Crater in the Erkuta River Valley, Yamal Peninsula: Characteristics and Potential Formation Model

Geosciences ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 170 ◽  
Author(s):  
Evgeny Chuvilin ◽  
Julia Stanilovskaya ◽  
Aleksey Titovsky ◽  
Anton Sinitsky ◽  
Natalia Sokolova ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
River Valley ◽  
Oxbow Lake ◽  
Yamal Peninsula ◽  
Permafrost Soil ◽  
Formation Model ◽  
Gas Emission ◽  
Ground Ice ◽  
Lake Formation ◽  
Potential Formation

Methane is a powerful greenhouse gas, and the abrupt degassing events that recently have formed large craters on the Russian Arctic Yamal and Gydan Peninsulas have caused major concern. Here we present field data on cover sediments and evolution of a gas-emission crater discovered in the Erkuta–Yakha River valley in the southern Yamal Peninsula in June 2017. The crater is located south of other similar craters discovered over the past decade in northern West Siberia. Data were collected during a field trip to the Erkuta crater in December 2017 which included field observations and sampling of permafrost soil and ground ice from the rim of the crater. All soil and ice samples were measured for contents of methane and its homologs (ethane and propane) and carbon dioxide. The contents of carbon dioxide in some samples are notably higher than methane. The strongly negative δ13С of methane from ground ice samples (−72‰) is typical of biogenic hydrocarbons. The ratio of methane to the total amount of its homologs indicate a component of gases that have migrated from a deeper, thermogenic source. Based on obtained results, a potential formation model for Erkuta gas-emission crater is proposed, which considers the combined effect of deep-seated (deep gas migration) and shallow (oxbow lake evolution and closed talik freezing) causes. This model includes several stages from geological prerequisites to the lake formation.

Sign in / Sign up

Export Citation Format

Share Document