Forest stability during the early and late Holocene in the igapó floodplains of the Rio Negro, northwestern Brazil

2017 ◽  
Vol 89 (1) ◽  
pp. 75-89 ◽  
Author(s):  
Paula A. Rodríguez-Zorro ◽  
Bruno Turcq ◽  
Renato C. Cordeiro ◽  
Luciane S. Moreira ◽  
Renata L. Costa ◽  
...  
Keyword(s):  
Late Holocene ◽  
Amazon Basin ◽  
Vegetation History ◽  
Sediment Cores ◽  
Northwestern Part ◽  
Human Disturbances ◽  
River Dynamics ◽  
Rio Negro ◽  
Igapó Forest ◽  
Forest Stability

AbstractLocated at the northwestern part of the Amazon basin, Rio Negro is the largest black-water river in the world and is one of the poorest studied regions of the Amazon lowlands. In the middle-upper part of the Rio Negro were retrieved sediment cores form Lake Acarabixi, which were analyzed using pollen, spores, charcoal, and geochemistry. The aim of this study was to detect the influences from humans and river dynamics on the vegetation history in the region. Two main periods of vegetation and river dynamics were detected. From 10,840 to 8240 cal yr BP, the river had a direct influence into the lake. The lake had a regional input of charcoal particles, which reflected the effect of the dry Holocene period in the basin. Furthermore, highland taxa such asHedyosmumandMyrsinewere found at that time along with igapó forest species that are characteristic to tolerate extended flooding likeEschweilera,Macrolobium, Myrtaceae,Swartzia, andAstrocaryum. During the late Holocene (1600 to 650 cal yr BP), more lacustrine phases were observed. There were no drastic changes in vegetation but the presence of pioneer species likeVismiaandCecropia, along with the signal of fires, which pointed to human disturbances.

Holocene Fires in the Northern Amazon Basin

1986 ◽  
Vol 26 (3) ◽  
pp. 358-366 ◽  
Author(s):  
Juan G. Saldarriaga ◽  
Darrell C. West
Keyword(s):  
Forest Soils ◽  
Amazon Basin ◽  
Soil Types ◽  
Human Disturbances ◽  
The Holocene ◽  
The Past ◽  
Rio Negro ◽  
Thermoluminescence Analysis

The ubiquitous occurrence of charcoal in the forest soils of the Upper Rio Negro region of Colombia and Venezuela indicates the presence of frequent and widespread fires in the Amazon Basin, possibly associated with extremely dry periods or human disturbances. Charcoal ranged from 3.12 to 24.76 mg/cm3 in the upper 50 cm of soil and was more abundant in Oxisols and Ultisols than in other soil types. Charcoal dates range from 6260 yr B.P. to the present. Several dates coincide with dry phases recorded during the Holocene. Ceramic shards were found at several sites, and thermoluminescence analysis indicates that their ages range from 3750 to 460 yr B.P. The age of charcoal and shards confirms that this region has been subjected to fire and human disturbances during the past 6000 yr.

Terrestrial and aquatic palynomorphs in Holocene sediments from the Chukchi–Alaskan margin, western Arctic Ocean: Implications for the history of marine circulation and climatic environments

The Holocene ◽  
2016 ◽  
Vol 27 (7) ◽  
pp. 976-986 ◽  
Author(s):  
So-Young Kim ◽  
Leonid Polyak ◽  
Irina Delusina
Keyword(s):  
Late Holocene ◽  
Vegetation History ◽  
Climatic Factors ◽  
Chukchi Sea ◽  
Sediment Cores ◽  
Depositional Environments ◽  
Chukchi Peninsula ◽  
Bering Strait ◽  
The Holocene ◽  
Paleoclimatic Changes

Two sediment cores from the Chukchi Sea margin north of Alaska were analyzed for palynological composition including terrestrial and aquatic palynomorphs. Based on 13 radiocarbon ages, the investigated sedimentary record represents most of the Holocene with a century to multidecadal age resolution. Three palynological zones were discriminated based on the abundance of major palynomorph groups (terrestrial and freshwater palynomorphs and dinoflagellate cysts) and composition of spore and pollen assemblages. They are interpreted in terms of depositional and paleoclimatic changes including predominance of redeposition by meltwater or sea ice in the early-Holocene, a strong input of contemporaneous material related to Pacific water advection culminating after ca. 6000 yr BP, and more subtle changes in the late-Holocene. It is concluded that depositional environments, such as current transportation and mixing, have an overall major control on palynomorph distribution. The climatic factors may have also played an important role in palynomorph abundance and composition, especially in the middle- to late-Holocene, when circulation changes were less dramatic than during the flooding of the Bering Strait and the shallow Chukchi Sea shelf. Comprehending these linkages requires a better knowledge of the Holocene vegetation history in the coastal areas of Alaska and Chukchi Peninsula.

A LATE HOLOCENE VEGETATION HISTORY OF LOWLAND GUATEMALA: RECORDS FROM LAKE IZABAL, EASTERN GUATEMALA

2020 ◽  
Author(s):  
Erdoo Mongol ◽  
◽  
Francisca E. Oboh-Ikuenobe ◽  
Jonathan Obrist-Farner ◽  
Alex Correa-Metrio
Keyword(s):  
Late Holocene ◽  
Vegetation History ◽  
History Of

scholarly journals Vulnerability of the North Water ecosystem to climate change

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Sofia Ribeiro ◽  
Audrey Limoges ◽  
Guillaume Massé ◽  
Kasper L. Johansen ◽  
William Colgan ◽  
...  
Keyword(s):  
Climate Change ◽  
Sea Ice ◽  
Late Holocene ◽  
Sediment Cores ◽  
Arctic Ecosystems ◽  
Little Auk ◽  
The North ◽  
Water Ecosystem ◽  
North Water

AbstractHigh Arctic ecosystems and Indigenous livelihoods are tightly linked and exposed to climate change, yet assessing their sensitivity requires a long-term perspective. Here, we assess the vulnerability of the North Water polynya, a unique seaice ecosystem that sustains the world’s northernmost Inuit communities and several keystone Arctic species. We reconstruct mid-to-late Holocene changes in sea ice, marine primary production, and little auk colony dynamics through multi-proxy analysis of marine and lake sediment cores. Our results suggest a productive ecosystem by 4400–4200 cal yrs b2k coincident with the arrival of the first humans in Greenland. Climate forcing during the late Holocene, leading to periods of polynya instability and marine productivity decline, is strikingly coeval with the human abandonment of Greenland from c. 2200–1200 cal yrs b2k. Our long-term perspective highlights the future decline of the North Water ecosystem, due to climate warming and changing sea-ice conditions, as an important climate change risk.

Mid- and late-Holocene vegetation history, climate and human impact in the forest-steppe ecotone of European Russia: new data and a regional synthesis

2016 ◽  
Vol 25 (12) ◽  
pp. 2453-2472 ◽  
Author(s):  
Elena Y. Novenko ◽  
Andrey N. Tsyganov ◽  
Olga V. Rudenko ◽  
Elena V. Volkova ◽  
Inna S. Zuyganova ◽  
...  
Keyword(s):  
Human Impact ◽  
Late Holocene ◽  
Vegetation History ◽  
European Russia ◽  
Forest Steppe

scholarly journals New species of Cyphocharax (Characiformes: Curimatidae) from the upper rio Negro, Amazon basin

2014 ◽  
Vol 12 (2) ◽  
pp. 327-332 ◽  
Author(s):  
Bruno F. Melo ◽  
Richard P. Vari
Keyword(s):  
New Species ◽  
Amazon Basin ◽  
Caudal Peduncle ◽  
Caudal Fin ◽  
Rio Negro ◽  
Fin Rays ◽  
Dark Pigmentation ◽  
Northern Brazil ◽  
Adipose Fin ◽  
A New Species

A new species of Cyphocharax, Curimatidae, apparently endemic to the blackwater upper rio Negro of the Amazon basin in northern Brazil, is described.The new species is readily distinguished from its congeners by the presence of a distinctly longitudinally elongate, posteriorly vertically expanding patch of dark pigmentation along the midlateral surface of the caudal peduncle, with the patch extending from the base of the middle caudal-fin rays anteriorly past the vertical through the posterior terminus of the adipose fin. The new species additionally differs from all congeners in details of body and fin pigmentation and meristic and morphometric ratios. Evidence for the assignment of the species to Cyphocharax and the occurrence of other species of the Curimatidae apparently endemic to the upper rio Negro catchment is discussed.

scholarly journals Redescription of Odontostilbe pulchra (Gill, 1858) (Teleostei: Characidae: Cheirodontinae), and description of two new species from the río Orinoco basin

2007 ◽  
Vol 5 (1) ◽  
pp. 1-20 ◽  
Author(s):  
Cristina M. Bührnheim ◽  
Luiz R. Malabarba
Keyword(s):  
New Species ◽  
South America ◽  
Amazon Basin ◽  
Rio Negro ◽  
Species Inquirenda ◽  
Two New Species ◽  
Northern South America

Odontostilbe pulchra, previously considered species inquirenda in Cheirodontinae and doubtfully assigned from the río Orinoco basin, is redescribed with the rediscovery of two syntypes. Originally described to the Island of Trinidad, O. pulchra is widespread in Venezuela, the río Orinoco basin, in smaller coastal drainages of northern South America, in the Lake Valencia system, and río Essequibo basin. A punctual occurrence in the upper rio Negro, near southernmost headwaters of the río Orinoco, extends its distribution to the Amazon basin. Additionally, two new species of Odontostilbe from the río Orinoco basin are described.

scholarly journals A taxonomic review of the species of CharaxScopoli, 1777 (Teleostei: Characidae: Characinae) with description of a new species from the rio Negro bearing superficial neuromasts on body scales, Amazon basin, Brazil

2014 ◽  
Vol 12 (2) ◽  
pp. 193-228 ◽  
Author(s):  
Naércio A. Menezes ◽  
Carlos Alberto S. de Lucena
Keyword(s):  
New Species ◽  
Geographic Distribution ◽  
Amazon Basin ◽  
Junior Synonym ◽  
Museum Collections ◽  
Taxonomic Review ◽  
Rio Negro ◽  
Three New Species ◽  
A New Species ◽  
Pelvic Fin

The species of Charaxwere reviewed by Lucena (1987) who a little later (1989) added three new species to the genus. Examination of recently collected specimens from museum collections documented the more extensive geographic distribution for most species and revealed the existence of a new species in which superficial neuromasts were discovered and are herein described. These skin structures were also detected in C. metae Eigenmann, 1922. Anal- and pelvic-fin hooks previously observed only on the anal-fin of one species of the genus are described herein in some other species. Charax unimaculatus Lucena is considered a junior synonym of C. michaeli Lucena. All the species are redescribed and the new species described.

scholarly journals Look Upstream: Measurement for Innovation on the Upper Rio Negro of the Amazon Basin

2021 ◽  
Vol 8 ◽  
Author(s):  
Kurt Shaw ◽  
Rita de Cácia Oenning da Silva
Keyword(s):  
Amazon Basin ◽  
Controlled Trial ◽  
Theory Of Change ◽  
Positive Development ◽  
Private Goods ◽  
Rio Negro ◽  
The Government ◽  
Traditional Songs ◽  
The Impact

The growth of the randomized controlled trial (RCT) as the “gold standard” for evaluation has justly been praised as an advance in the professionalization of social programs and projects, an “adoption of science” - in the words of the Lancet. None the less, the emphasis on the RCT biases funding for projects that distribute private goods and which focus on “low hanging fruit” in health, nutrition, and sanitation, simply because those areas lend themselves to the sort of measurement that works with RCTs. As a result, many project developers in the government and NGO sectors lament that a hegemonic focus on RCTs impedes creativity or new models that challenge traditional paradigms. This case study of CanalCanoa, a community video coaching project for indigenous parents of young children in the Rio Negro region of the Amazon Basin, offers techniques to measure for innovation. Instead of developing a new RCT for an extremely diverse population (27 ethnic groups) where traditional childcare methods are in historical flux because of urbanization, CanalCanoa measured variables shown by previous RCTs to be causally connected with positive development results. By researching the impact of the intervention on nutrition, language (multilingualism, use of traditional songs and stories), and social network expansion, CanalCanoa measured upstream indicators, thus mixing scientific rigor with an opportunity for innovation and providing important insight and reform of a theory of change.

scholarly journals 240+239Pu depositional signatures as a viable geochronological tool in the Amazon Basin

2017 ◽  
Vol 44 (1) ◽  
pp. 142-149 ◽  
Author(s):  
Luciana M Sanders ◽  
Kathryn H Taffs ◽  
Debra Stokes ◽  
Alex Enrich-Prast ◽  
Christian J Sanders
Keyword(s):  
Amazon Basin ◽  
Environmental Science ◽  
Sediment Cores ◽  
Sediment Accumulation ◽  
Recent Sediment ◽  
Floodplain Lake ◽  
Accumulation Rates ◽  
Amazon Floodplain ◽  
Dating Methods ◽  
Lead 210

AbstractAnthropogenic radionuclide signatures associated with nuclear testing are increasingly utilized in environmental science to explore recent sedimentation. In this study, we assess the suitability of Pu radioisotope analysis in floodplain lake environments in the Amazon Basin to form geochronologies during the 20thcentury. The240Pu +239Pu (240+239Pu) signatures in six sediment cores indicate sediment accumulation rates in the floodplain lakes of the major rivers; Amazon (2.3 mm year-1), Tapajos (10.2 and 2.4 mm year-1) and Madeira (3.4, 4.2 and 6.2 mm year-1). The results from this study show that240+239Pu fallout activities, and the well documented (240Pu/239Pu) atomic ratios of the above ground nuclear tests which began in the 1950’s, are sufficient and well preserved in Amazon floodplain lake sediments to infer chronologies. Lead-210 dating analyses in the same sediment cores produced comparable sediment accumulation rates at three of the six sites. The differences between dating methods may be attributed to the different time scale these dating methods represent and/or in the solubility between Pb and Pu along the sediment column. The geochronologies derived from the240+239Pu and210Pb dating methods outlined in this work are of interest to identify the effects of changing sediment accumulation rates during the previous century as a result of development, including deforestation, along the Amazon Basin which increased towards the middle of the 20thcentury. This study shows that Pu dating provides a viable alternative geochronology tool for recent sediment accumulation (previous ~60 years) along the Amazon Basin.

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