The collapse of megafaunal populations in southeastern Brazil

2017 ◽  
Vol 89 (1) ◽  
pp. 103-118 ◽  
Author(s):  
Marco F. Raczka ◽  
Mark B. Bush ◽  
Paulo Eduardo De Oliveira
Keyword(s):  
Climate Change ◽  
South America ◽  
Population Decline ◽  
Southeastern Brazil ◽  
Population Recovery ◽  
Population Declines ◽  
Human Occupation ◽  
Data Set ◽  
Ecological Implications ◽  
Functional Extinction

AbstractWhether humans or climate change caused the extinction of megafaunal populations is actively debated. Caves in the Lagoa Santa provide mixed assemblages of megafauna and human remains; however, it remains uncertain the extent to which humans and megafauna interacted or overlapped temporally. Here we present the first paleoecological record from lowland South America that tracks the decline of megafauna and its ecological implications. We provide a data set for pollen, charcoal, and Sporormiella, from two lakes in southeastern Brazil that span the last 23,000 yr. The data showed reduced abundances of Sporormiella and an inferred megafaunal population decline that began 18,000 yr ago, with the functional extinction occurring between 12,000 and 11,500 yr ago. Population declines coincided with wet events. The age of the final megafaunal decline is within the range of the first human occupation of the region. Our data are consistent with climate causing the population collapse, with humans preventing population recovery and inducing extinction. We did not observe some of the ecological repercussions documented at other sites and attributed to the megafaunal extinction. Habitat-specific ecological consequences of the extinction add to the heterogeneity of late Pleistocene and early Holocene landscapes.

scholarly journals Widespread population decline in South America correlates with mid-Holocene climate change

2018 ◽  
Author(s):  
Philip Riris ◽  
Manuel Arroyo-Kalin
Keyword(s):  
Climate Change ◽  
South America ◽  
Large Scale ◽  
Climatic Variability ◽  
Population Decline ◽  
Plant Management ◽  
Human Populations ◽  
Resource Base ◽  
Radiocarbon Dates ◽  
Middle Holocene

Quantifying the impacts of climate change on prehistoric demography is crucial for understanding the adaptive pathways taken by human populations. Archaeologists across South America have pointed to patterns of regional abandonment during the Middle Holocene (8200 to 4200 cal BP) as evidence of sensitivity to shifts in hydroclimate over this period. We develop a unified approach to investigate demography and climate in South America and aim to clarify the extent to which evidence of local anthropic responses can be generalised to large-scale trends. We achieve this by integrating archaeological radiocarbon data and palaeoclimatic time series to show that population decline occurred coeval with the transition to the initial mid-Holocene across South America. Through the analysis of radiocarbon dates with Monte Carlo methods, we find multiple, sustained phases of downturn associated to periods of high climatic variability. A likely driver of the duration and severity of demographic turnover is the frequency of exceptional climatic events, rather than the absolute magnitude of change. Unpredictable levels of tropical precipitation had sustained negative impacts on pre-Columbian populations lasting until at least 6000 cal BP, after which recovery is evident. Our results support the inference that a demographic regime shift in the second half of the Middle Holocene were coeval with cultural practices surrounding Neotropical plant management and early cultivation, possibly acting as buffers when the wild resource base was in flux.

scholarly journals Hunting pressure is a key contributor to the impending extinction of Bornean wild cattle

2021 ◽  
Vol 45 ◽  
pp. 225-235
Author(s):  
PC Gardner ◽  
B Goossens ◽  
SBA Bakar ◽  
MW Bruford
Keyword(s):  
Population Growth ◽  
Captive Breeding ◽  
Population Decline ◽  
Active Management ◽  
Population Recovery ◽  
Central Unit ◽  
Population Parameters ◽  
Population Declines ◽  
Bos Javanicus ◽  
In The Wild

Widespread and unregulated hunting of ungulates in Southeast Asia is resulting in population declines and localised extinctions. Increased access to previously remote tropical forest following logging and changes in land-use facilitates hunting of elusive wild cattle in Borneo, which preferentially select secluded habitat. We collated the first population parameters for the Endangered Bornean banteng Bos javanicus lowi and developed population models to simulate the effect of different hunting offtake rates on survival and the recovery of the population using reintroduced captive-bred individuals. Our findings suggest that the banteng population in Sabah is geographically divided into 4 management units based on connectivity: the Northeast, Sipitang (West), Central and Southeast, which all require active management to prevent further population decline and local extinction. With only 1% offtake, population growth ceased in the Northeast and Sipitang. In the Southeast and Central units, growth ceased at 2 and 4% offtake, respectively. Extinction was estimated at 21-39 yr when offtake was 5%, occurring first in Sipitang and last in the Central unit. Supplementing the population with captive-bred individuals suggested that inbreeding was likely to limit population growth if using ≤20 founder individuals. Translocating 2 individuals for a 10 yr period, starting after 20 yr of captive breeding resulted in a faster population recovery over 100 yr and a lower extinction probability. Our results suggest that shielding the population against further losses from hunting will be key to their survival in the wild, provided that active management in the form of captive breeding is developed in the interim.

Configurations to Superior Environmental Innovation Strategy: A Both–And Approach

2021 ◽  
pp. 108602662110316
Author(s):  
Tiziana Russo-Spena ◽  
Nadia Di Paola ◽  
Aidan O’Driscoll
Keyword(s):  
Climate Change ◽  
Value Chain ◽  
Critical Role ◽  
Well Being ◽  
Point Of View ◽  
Future Generations ◽  
Innovation Strategy ◽  
Environmental Innovation ◽  
Data Set

An effective climate change action involves the critical role that companies must play in assuring the long-term human and social well-being of future generations. In our study, we offer a more holistic, inclusive, both–and approach to the challenge of environmental innovation (EI) that uses a novel methodology to identify relevant configurations for firms engaging in a superior EI strategy. A conceptual framework is proposed that identifies six sets of driving characteristics of EI and two sets of beneficial outcomes, all inherently tensional. Our analysis utilizes a complementary rather than an oppositional point of view. A data set of 65 companies in the ICT value chain is analyzed via fuzzy-set comparative analysis (fsQCA) and a post-QCA procedure. The results reveal that achieving a superior EI strategy is possible in several scenarios. Specifically, after close examination, two main configuration groups emerge, referred to as technological environmental innovators and organizational environmental innovators.

scholarly journals Anthropogenic climate change has changed frequency of past flood during 2010-2013

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Yukiko Hirabayashi ◽  
Haireti Alifu ◽  
Dai Yamazaki ◽  
Yukiko Imada ◽  
Hideo Shiogama ◽  
...  
Keyword(s):  
Climate Change ◽  
South America ◽  
Radiative Forcing ◽  
Water Cycle ◽  
Flood Frequency ◽  
Anthropogenic Climate Change ◽  
Climate Change Signal ◽  
Northern Eurasia ◽  
Large Ensemble ◽  
The Impact

AbstractThe ongoing increases in anthropogenic radiative forcing have changed the global water cycle and are expected to lead to more intense precipitation extremes and associated floods. However, given the limitations of observations and model simulations, evidence of the impact of anthropogenic climate change on past extreme river discharge is scarce. Here, a large ensemble numerical simulation revealed that 64% (14 of 22 events) of floods analyzed during 2010-2013 were affected by anthropogenic climate change. Four flood events in Asia, Europe, and South America were enhanced within the 90% likelihood range. Of eight snow-induced floods analyzed, three were enhanced and four events were suppressed, indicating that the effects of climate change are more likely to be seen in the snow-induced floods. A global-scale analysis of flood frequency revealed that anthropogenic climate change enhanced the occurrence of floods during 2010-2013 in wide area of northern Eurasia, part of northwestern India, and central Africa, while suppressing the occurrence of floods in part of northeastern Eurasia, southern Africa, central to eastern North America and South America. Since the changes in the occurrence of flooding are the results of several hydrological processes, such as snow melt and changes in seasonal and extreme precipitation, and because a climate change signal is often not detectable from limited observation records, large ensemble discharge simulation provides insights into anthropogenic effects on past fluvial floods.

scholarly journals Future climate change will impact the size and location of breeding and wintering areas of migratory thrushes in South America

The Condor ◽  
2021 ◽  
Author(s):  
Natália Stefanini Da Silveira ◽  
Maurício Humberto Vancine ◽  
Alex E Jahn ◽  
Marco Aurélio Pizo ◽  
Thadeu Sobral-Souza
Keyword(s):  
Climate Change ◽  
South America ◽  
Migratory Birds ◽  
Global Climate ◽  
Future Climate ◽  
Future Climate Change ◽  
Ecological Niche Models ◽  
Global Climate Changes ◽  
The Andes ◽  
Wintering Areas

Abstract Bird migration patterns are changing worldwide due to current global climate changes. Addressing the effects of such changes on the migration of birds in South America is particularly challenging because the details about how birds migrate within the Neotropics are generally not well understood. Here, we aim to infer the potential effects of future climate change on breeding and wintering areas of birds that migrate within South America by estimating the size and elevations of their future breeding and wintering areas. We used occurrence data from species distribution databases (VertNet and GBIF), published studies, and eBird for 3 thrush species (Turdidae; Turdus nigriceps, T. subalaris, and T. flavipes) that breed and winter in different regions of South America and built ecological niche models using ensemble forecasting approaches to infer current and future potential distributions throughout the breeding and wintering periods of each species. Our findings point to future shifts in wintering and breeding areas, mainly through elevational and longitudinal changes. Future breeding areas for T. nigriceps, which migrates along the Andes Mountains, will be displaced to the west, while breeding displacements to the east are expected for the other 2 species. An overall loss in the size of future wintering areas was also supported for 2 of the species, especially for T. subalaris, but an increase is anticipated for T. flavipes. Our results suggest that future climate change in South America will require that species shift their breeding and wintering areas to higher elevations in addition to changes in their latitudes and longitude. Our findings are the first to show how future climate change may affect migratory birds in South America throughout the year and suggest that even closely related migratory birds in South America will be affected in different ways, depending on the regions where they breed and overwinter.

scholarly journals Comparison of <i>H</i> component geomagnetic field time series obtained at different sites over South America

2018 ◽  
Vol 36 (3) ◽  
pp. 937-943 ◽  
Author(s):  
Maurício J. A. Bolzan ◽  
Clezio M. Denardini ◽  
Alexandre Tardelli
Keyword(s):  
South America ◽  
Geomagnetic Field ◽  
Phase Coherence ◽  
South American ◽  
Data Set ◽  
Geomagnetism And Paleomagnetism ◽  
Strong Phase ◽  
Geomagnetic Fields ◽  
Time Variations ◽  
Physical Phenomena

Abstract. The geomagnetic field in the Brazilian sector is influenced by the South American Magnetic Anomaly (SAMA) that causes a decrease in the magnitude of the local geomagnetic field when compared to other regions in the world. Thus, the magnetometer network and data set of space weather over Brazil led by Embrace are important tools for promoting the understanding of geomagnetic fields over Brazil. In this sense, in this work we used the H component of geomagnetic fields obtained at different sites in South America in order to compare results from the phase coherence obtained from wavelet transform (WT). Results from comparison between Cachoeira Paulista (CXP) and Eusébio (EUS), and Cachoeira Paulista and São Luis (SLZ), indicated that there exist some phenomena that occur simultaneously in both locations, putting them in the same phase coherence. However, there are other phenomena putting both locations in a strong phase difference as observed between CXP and Rio Grande, Argentina (RGA). This study was done for a specific moderate geomagnetic storm that occurred in March 2003. The results are explained in terms of nonlinear interaction between physical phenomena acting in distinct geographic locations and at different times and scales. Keywords. Geomagnetism and paleomagnetism (time variations – diurnal to secular)

scholarly journals Observed Trends in Indices of Daily Temperature Extremes in South America 1960–2000

2005 ◽  
Vol 18 (23) ◽  
pp. 5011-5023 ◽  
Author(s):  
L. A. Vincent ◽  
T. C. Peterson ◽  
V. R. Barros ◽  
M. B. Marino ◽  
M. Rusticucci ◽  
...  
Keyword(s):  
Climate Change ◽  
South America ◽  
Climate Extremes ◽  
Daily Temperature ◽  
Maximum Temperature ◽  
Daily Minimum Temperature ◽  
Daily Maximum Temperature ◽  
Daily Maximum ◽  
Temperature Extremes ◽  
Increasing Trends

Abstract A workshop on enhancing climate change indices in South America was held in Maceió, Brazil, in August 2004. Scientists from eight southern countries brought daily climatological data from their region for a meticulous assessment of data quality and homogeneity, and for the preparation of climate change indices that can be used for analyses of changes in climate extremes. This study presents an examination of the trends over 1960–2000 in the indices of daily temperature extremes. The results indicate no consistent changes in the indices based on daily maximum temperature while significant trends were found in the indices based on daily minimum temperature. Significant increasing trends in the percentage of warm nights and decreasing trends in the percentage of cold nights were observed at many stations. It seems that this warming is mostly due to more warm nights and fewer cold nights during the summer (December–February) and fall (March–May). The stations with significant trends appear to be located closer to the west and east coasts of South America.

scholarly journals Comparing maternal genetic variation across two millennia reveals the demographic history of an ancient human population in southwest Turkey

2016 ◽  
Vol 3 (2) ◽  
pp. 150250 ◽  
Author(s):  
Claudio Ottoni ◽  
Rita Rasteiro ◽  
Rinse Willet ◽  
Johan Claeys ◽  
Peter Talloen ◽  
...  
Keyword(s):  
Demographic History ◽  
Population Decline ◽  
Fifth Century ◽  
Seventh Century ◽  
Human Occupation ◽  
Dna Variation ◽  
Genetic Discontinuity ◽  
History Of ◽  
The City ◽  
Modern Sample

More than two decades of archaeological research at the site of Sagalassos, in southwest Turkey, resulted in the study of the former urban settlement in all its features. Originally settled in late Classical/early Hellenistic times, possibly from the later fifth century BCE onwards, the city of Sagalassos and its surrounding territory saw empires come and go. The Plague of Justinian in the sixth century CE, which is considered to have caused the death of up to a third of the population in Anatolia, and an earthquake in the seventh century CE, which is attested to have devastated many monuments in the city, may have severely affected the contemporary Sagalassos community. Human occupation continued, however, and Byzantine Sagalassos was eventually abandoned around 1200 CE. In order to investigate whether these historical events resulted in demographic changes across time, we compared the mitochondrial DNA variation of two population samples from Sagalassos (Roman and Middle Byzantine) and a modern sample from the nearby town of Ağlasun. Our analyses revealed no genetic discontinuity across two millennia in the region and Bayesian coalescence-based simulations indicated that a major population decline in the area coincided with the final abandonment of Sagalassos, rather than with the Plague of Justinian or the mentioned earthquake.

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