Consulta: creatorFacets:"Bush,Mark B."
Registros recuperados: 4
Data/hora: 11/06/2024 13:28:53

A Holocene pollen record of savanna establishment in coastal Amapá
Provedor de dados: 42
Autores: Toledo,Mauro B. de; Bush,Mark B.
The main goal of this study was to investigate how climate and human activities may have influenced ecotonal areas of disjoint savannas within Brazilian Amazonia. The fossil pollen and charcoal records of Lake Márcio (Amapá) were used to provide a Holocene palaeoecological history of this region. Detrended correspondence analysis (DCA) was used to enhance the patterns of sample distribution along the sediment core. A marked vegetation change from closed forests with swamp elements to open flooded savanna at c. 5000 yrs BP was evident from the pollen record. Charcoal analysis revealed a pattern of increased accumulation of particles coincident with the establishment of savannas, suggesting higher fire frequency and human impacts near the lake. A 550-year...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Pollen record; Palaeofires; Amazonia; Savannas; Climate change; Palaeoecology.
Ano: 2008
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652008000200013

Vegetation and hydrology changes in Eastern Amazonia inferred from a pollen record
Provedor de dados: 42
Autores: Toledo,Mauro B. de; Bush,Mark B.
Pollen, charcoal, and C14 analyses were performed on a sediment core obtained from Lake Tapera (Amapá) to provide the palaeoenvironmental history of this part of Amazonia. A multivariate analysis technique, Detrended Correspondence Analysis, was applied to the pollen data to improve visualization of sample distribution and similarity. A sedimentary hiatus lasting 5,500 years was identified in the Lake Tapera. Because the timing of the hiatus overlapped with the highest Holocene sea-level, which would have increased the local water table preventing the lake from drying out, it is clear that sea-level was not important in maintaining the lake level. Lake Tapera probably depended on riverine flood waters, and the sedimentary gap was caused by reduced Amazon...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Vegetation change; Hydrology change; Amazonia; Pollen record; Climate change.
Ano: 2008
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652008000100014

The rise and fall of the Refugial Hypothesis of Amazonian speciation: a paleoecological perspective
Provedor de dados: 49
Autores: Bush,Mark B.; Oliveira,Paulo E. de.
The refugial hypothesis is treated as the definitive history of Amazonian forests in many texts. Surprisingly, this important theoretical framework has not been based on paleoecological data. Consequently, a model of Amazonian aridity during the northern hemispheric glaciation has been accepted uncritically. Ironically, the Refuge Hypothesis has not been tested by paleobotanical data. We present a revision of the concept of Neotropical Pleistocene Forest Refuges and test it in the light of paleocological studies derived from pollen analysis of Amazonian lake sediments deposited during the last 20,000 years. Our analysis is based primarily on paleoenvironmental data obtained from sites in Brazil and Ecuador. These data are contrasted with those that favor...
Tipo: Info:eu-repo/semantics/other
Palavras-chave: Amazonia; Refugia; Fossil pollen; Glaciations; Pleistocene; Holocene; Miocene; Phylogeny; Speciation diversity.
Ano: 2006
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1676-06032006000100002

Sporormiella as a tool for detecting the presence of large herbivores in the Neotropics
Provedor de dados: 49
Autores: Raczka,Marco Felipe; Bush,Mark B.; Folcik,Alexandra M.; McMichael,Crystal H.
The reliability of using the abundance of Sporormiella spores as a proxy for the presence and abundance of megaherbivores was tested in southern Brazil. Mud-water interface samples from nine lakes, in which cattle-use was categorized as high, medium, or low, were assayed for Sporormiella representation. The sampling design allowed an analysis of both the influence of the number of animals using the shoreline and the distance of the sampling site from the nearest shoreline. Sporormiella was found to be a reliable proxy for the presence of large livestock. The concentration and abundance of spores declined from the edge of the lake toward the center, with the strongest response being in sites with high livestock use. Consistent with prior studies in...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Extinction; Fossil pollen; Lake sediment; Livestock; Pleistocene Megafauna; Sporormiella spores.
Ano: 2016
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1676-06032016000100110