scholarly journals Some palaeoecological data from Rondonia, southern part of the Amazon Basin. ()

1976 ◽  
Vol 6 (3) ◽  
pp. 293-299 ◽  
Author(s):  
Maria Lúcia Absy ◽  
Th. van der Hammen
Keyword(s):  
Tropical Forest ◽  
Amazon Basin ◽  
Sediment Cores ◽  
Climatic Changes ◽  
Late Cenozoic ◽  
Upper Pleistocene ◽  
Several Intervals

Abstract Palynological investigations on sediment cores from three localities in Rondonia in the southern part of the Amazon Basin, indicate that marked vegetational changes have ocurred there. The series of samples from Katira represents the late Cenozoic, probably Quaternary. The sediments from Capoeira might be partly of Holocene age (and possibly Upper Pleistocene as well). Apparently the climatic changes during several intervals of the Late Cenozoic (Quaternary) caused the development of savannas in this region which is now covered in tropical forest.

Flesh flies (Diptera: Sarcophagidae) from a white-sand habitat in the Brazilian Amazon, with the description of four new species

Zootaxa ◽  
2018 ◽  
Vol 4504 (3) ◽  
pp. 401
Author(s):  
FERNANDO DA SILVA CARVALHO-FILHO ◽  
INOCÊNCIO DE SOUSA GORAYEB ◽  
JÉSSICA MARIA MENEZES SOARES ◽  
MATHEUS TAVARES DE SOUZA
Keyword(s):  
New Species ◽  
Tropical Forest ◽  
Amazon Basin ◽  
Vegetation Type ◽  
Brazilian Amazon ◽  
Insect Fauna ◽  
Flesh Fly ◽  
Small Areas ◽  
White Sand ◽  
Flesh Flies

The white-sand enclaves in the Amazon Basin are small areas scattered through the tropical forest, with sandy and nutrient-poor soils and an unusual vegetation type. The insect fauna of this ecosystem is poorly known, especially in the eastern Amazon. The flesh fly fauna of an area of open herbaceous white-sand vegetation known as “Campo Redondo” in the municipality of Cametá, state of Pará, was surveyed, resulting in the discovery of 43 species in 11 genera representing the subfamilies Sarcophaginae and Miltogramminae. Four new species are described: Dexosarcophaga (Dexosarcophaga) campina sp. nov., Helicobia cametaensis sp. nov., Helicobia domquixote sp. nov., and Metopia fofo sp. nov. Lepidodexia (Lepidodexia) grisea Lopes and Lepidodexia (Notochaeta) setifrons (Lopes) are newly recorded from Brazil. Dexosarcophaga (Bezzisca) ampullula (Engel), D. (Dexosarcophaga) transita Townsend and Titanogrypa (Cucullomyia) larvicida (Lopes) are newly recorded from the Brazilian Amazon. 

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.

scholarly journals Steady erosion rates in the Himalayas through late Cenozoic climatic changes

2020 ◽  
Vol 13 (6) ◽  
pp. 448-452 ◽  
Author(s):  
Sebastien J. P. Lenard ◽  
Jérôme Lavé ◽  
Christian France-Lanord ◽  
Georges Aumaître ◽  
Didier L. Bourlès ◽  
...  
Keyword(s):  
Climatic Changes ◽  
Late Cenozoic ◽  
Erosion Rates

scholarly journals Analysing Amazonian forest productivity using a new individual and trait-based model (TFS v.1)

2014 ◽  
Vol 7 (4) ◽  
pp. 1251-1269 ◽  
Author(s):  
N. M. Fyllas ◽  
E. Gloor ◽  
L. M. Mercado ◽  
S. Sitch ◽  
C. A. Quesada ◽  
...  
Keyword(s):  
Tropical Forest ◽  
Functional Traits ◽  
Amazon Basin ◽  
Census Data ◽  
Soil Nutrient ◽  
Forest Growth ◽  
High Rate ◽  
Mean Annual Precipitation ◽  
Water Fluxes ◽  
Amazonian Forest

Abstract. Repeated long-term censuses have revealed large-scale spatial patterns in Amazon basin forest structure and dynamism, with some forests in the west of the basin having up to a twice as high rate of aboveground biomass production and tree recruitment as forests in the east. Possible causes for this variation could be the climatic and edaphic gradients across the basin and/or the spatial distribution of tree species composition. To help understand causes of this variation a new individual-based model of tropical forest growth, designed to take full advantage of the forest census data available from the Amazonian Forest Inventory Network (RAINFOR), has been developed. The model allows for within-stand variations in tree size distribution and key functional traits and between-stand differences in climate and soil physical and chemical properties. It runs at the stand level with four functional traits – leaf dry mass per area (Ma), leaf nitrogen (NL) and phosphorus (PL) content and wood density (DW) varying from tree to tree – in a way that replicates the observed continua found within each stand. We first applied the model to validate canopy-level water fluxes at three eddy covariance flux measurement sites. For all three sites the canopy-level water fluxes were adequately simulated. We then applied the model at seven plots, where intensive measurements of carbon allocation are available. Tree-by-tree multi-annual growth rates generally agreed well with observations for small trees, but with deviations identified for larger trees. At the stand level, simulations at 40 plots were used to explore the influence of climate and soil nutrient availability on the gross (ΠG) and net (ΠN) primary production rates as well as the carbon use efficiency (CU). Simulated ΠG, ΠN and CU were not associated with temperature. On the other hand, all three measures of stand level productivity were positively related to both mean annual precipitation and soil nutrient status. Sensitivity studies showed a clear importance of an accurate parameterisation of within- and between-stand trait variability on the fidelity of model predictions. For example, when functional tree diversity was not included in the model (i.e. with just a single plant functional type with mean basin-wide trait values) the predictive ability of the model was reduced. This was also the case when basin-wide (as opposed to site-specific) trait distributions were applied within each stand. We conclude that models of tropical forest carbon, energy and water cycling should strive to accurately represent observed variations in functionally important traits across the range of relevant scales.

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.

scholarly journals 10Be records of sediment cores from high northern latitudes: Implications for environmental and climatic changes

1994 ◽  
Vol 124 (1-4) ◽  
pp. 171-184 ◽  
Author(s):  
A. Eisenhauer ◽  
R.F. Spielhagen ◽  
M. Frank ◽  
G. Hentzschel ◽  
A. Mangini ◽  
...  
Keyword(s):  
Sediment Cores ◽  
Climatic Changes ◽  
Northern Latitudes

scholarly journals Avifauna of the upper Purus River: relevant records for an area lacking ornithological surveys

2021 ◽  
Vol 61 ◽  
pp. e20216121
Author(s):  
Fernando Igor de Godoy ◽  
Edson Guilherme ◽  
Diego Pedroza ◽  
Ricardo Antônio de Andrade Plácido
Keyword(s):  
Tropical Forest ◽  
Amazon Basin ◽  
Bird Species ◽  
Field Trips ◽  
The State ◽  
Knowledge Gaps ◽  
Number Of Species ◽  
Local Environments ◽  
The World ◽  
High Diversity

Birds are the best-known vertebrate group, although many localities in the world are considered to be knowledge gaps. This is the case of many little-known environments in the Amazon biome, the world’s largest tropical forest. Here, we present a survey of birds in the upper Purus basin, comprising the municipalities of Manoel Urbano and Feijó in the Brazilian state of Acre, and Boca do Acre and Pauini in the state of Amazonas. In this region, poorly-studied habitats, such as open rainforest dominated by palms or bamboo, still predominate. We recorded 452 bird species during 45 field trips between May and July in 2016, and June to August in 2017. Twenty-four of these species are associated with bamboo habitat, 28 are endemic to the southwestern Amazon basin, and seven are threatened with extinction. This high diversity is typical of the western Amazon basin, one of the richest regions in the world in the number of species, due to the heterogeneity of the local environments. The data presented here highlight the importance of the region for the conservation of birds, including species typical of the western Amazon, some of which are still poorly-known.

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