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Vegetation dynamics during the late Pleistocene in the Barreirinhas region, Maranhão State, northeastern Brazil, based on carbon isotopes in soil organic matter |
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| Authors: | Luiz Carlos Ruiz Pessenda Adauto de Souza Ribeiro Ramon Aravena José Albertino Bendassolli |
| Institution: | a Center for Nuclear Energy in Agriculture (CENA), 13400-000, Piracicaba/SP, Brazil b Federal University of Sergipe, Aracaju/SE, Brazil c University of Waterloo, Waterloo, Ontario, Canada N2L3G1 d IRD, Geosciences Institute/University of São Paulo, 05508-900, São Paulo/SP, Brazil |
| Abstract: | The study place is in the Barreirinhas region, Maranhão State, northeastern Brazil. A vegetation transect of 78 km was studied among four vegetation types: Restinga (coastal vegetation), Cerrado (woody savanna), Cerradão (dense woody savanna), and Forest, as well as three forested sites around Lagoa do Caçó, located approximately 10 km of the transect. Soil profiles in this transect were sampled for δ13C analysis, as well as buried charcoal fragments were used for 14C dating. The data interpretation indicated that approximately between 15,000 and ∼9000 14C yr B.P., arboreal vegetation prevailed in the whole transect, probably due to the presence of a humid climate. Approximately between ∼9000 and 4000-3000 14C yr B.P., there was the expansion of the savanna, probably related to the presence of drier climate. From ∼4000-3000 14C yr B.P. to the present, the results indicated an increase in the arboreal density in the area, due to the return to a more humid and probably similar climate to the present. The presence of buried charcoal fragments in several soil depths suggested the occurrence of palaeofires during the Holocene. The vegetation dynamic inferred in this study for northeastern Brazil is in agreement with the results obtained in areas of Amazon region, based on pollen analysis of lake sediments and carbon isotope analysis of soil organic matter (SOM), implying than similar climatic conditions have affected these areas during the late Pleistocene until the present. |
| Keywords: | Barreirinhas region Carbon isotopes Soil organic matter |
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