Fire events and vegetation dynamics during the late Pleistocene-Meghalayan interval in the southernmost Brazilian coastal plain
| Autor: | Ricardo Burgo Braga, Lidia Aumond Kuhn, Rualdo Menegat, Wagner Guimarães da Silva, Veridiana Ribeiro, Soraia Girardi Bauermann, Jefferson Cardia Simões, Margot Guerra-Sommer |
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| Rok vydání: | 2020 |
| Předmět: |
Palynology
Peat geography.geographical_feature_category 010504 meteorology & atmospheric sciences Pleistocene Coastal plain Paleontology Forestry 010502 geochemistry & geophysics Vegetation dynamics 01 natural sciences Geography visual_art visual_art.visual_art_medium Glacial period Charcoal Holocene 0105 earth and related environmental sciences |
| Zdroj: | Revista Brasileira de Paleontologia. 23:234-250 |
| ISSN: | 2236-1715 1519-7530 |
| DOI: | 10.4072/rbp.2020.4.02 |
| Popis: | The present study analyzes the correspondence between charcoal concentrations and changes in the palynological composition in a core from Aguas Claras peatland (30o06’24.39” S; 50o49’04.90” W) in the coastal plain of southernmost Brazil (Rio Grande do Sul State) from approximately 38,900 yrs BP until 1,500 yrs BP. The dominance of grassland vegetation (mainly Poaceae) in Late Pleistocene sediments persisted into the Holocene during the development of a peatland. Analysis of fragment size distribution and concentration were useful to discriminate local fires from regional wildfires. Late Pleistocene regional fires registered in shallow pond deposits (older than 21,545 cal yrs BP) were distinguished from a local Holocene fire by the presence of higher proportions of small particles in charcoal assemblages. A charcoal peak related to a natural fire signal, composed by high concentration of charcoal with larger diameters, was identified at the topmost level of the peat facies (1,590–1,515 cal yrs BP). Correlated with palynological data, this charcoal peak originated by local fires indicates a change in vegetation during a dry climate interval that occurred around 1,500–1,600 yrs BP. Keywords: charcoal peak, palynology, climate, Holocene. RESUMO – O presente estudo analisa a correspondencia entre as concentracoes de carvao vegetal e as alteracoes na composicao palinologica em um testemunho sedimentar da turfeira de Aguas Claras (30o06’24,39” S; 50o49’04,90”O) na planicie costeira do extremo sul do Brasil (Rio Grande do Sul) em um intervalo de cerca de 38.900 anos AP a 1.500 anos AP. A dominância de vegetacao herbacea (principalmente Poaceae) no intervalo glacial tardio do Neopleistoceno persistiu ate o Holoceno, durante o desenvolvimento de uma turfeira. A analise da distribuicao e concentracao de tamanho dos fragmentos de charcoal foi utilizada para distinguir incendios florestais locais de incendios regionais. Incendios regionais no Neopleistoceno (mais antigos do que 21.545 anos cal AP) foram diferenciados de um incendio local do Holoceno, dadas as grandes quantidades de pequenos fragmentos de charcoal com diâmetros semelhantes. Um pico de charcoal que corresponde a um sinal incendio natural, composto por alta concentracao de fragmentos com grandes diâmetros indicando incendio local, foi identificado no nivel de topo de facies originadas em turfeira (1.590–1.515 anos cal AP). Esse pico de charcoal, correlacionado aos dados palinologicos, indicou uma mudanca na vegetacao relacionada a um intervalo climatico de seca que ocorreu por volta de 1.500–1.600 anos AP. Palavras-chave: pico de carvao vegetal, palinologia, clima, Holoceno. |
| Databáze: | OpenAIRE |
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