The evolution of a tropical rainforest/grassland mosaic in southeastern Brazil since 28,000 C yr BP based on carbon isotopes and pollen records |
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| Authors: | Luiz Carlos Ruiz Pessenda Paulo Eduardo De Oliveira Milene Mofatto Vanda Brito de Medeiros Ricardo Jos Francischetti Garcia Ramon Aravena Jos Albertino Bendassoli Accio Zuniga Leite Antonio Roberto Saad Mario Lincoln Etchebehere |
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| Institution: | aCenter for Nuclear Energy in Agriculture (CENA), 13400-000, Piracicaba/SP, Brazil;bUniversity of Guarulhos (UNG), Guarulhos/SP, Brazil;cHerbário da Prefeitura Municipal de São Paulo, São Paulo/SP, Brazil;dUniversity of Waterloo, Waterloo, Ontario, Canada N2L3G1 |
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| Abstract: | The lack of paleoecological records from the montane Atlantic Rainforest of coastal Brazil, a hotspot of biological diversity, has been a major obstacle to our understanding of the vegetational changes since the last glacial cycle. We present carbon isotope and pollen records to assess the impact of the glaciation on the native vegetation of the Serra do Mar rainforest in São Paulo, Brazil. From ca. 28,000 to  22,000 14C yr BP, a subtropical forest with conifer trees is indicative of cool and humid conditions. In agreement carbon isotopic data on soil organic matter suggest the presence of C3 plants and perhaps C4 plants from 28,000 to 19,000 14C yr BP. The significant increase in the sedimentation rate and algal spores from 19,450 to 19,000 14C yr BP indicates increasing humidity, associated to an erosion process between 19,000 and 15,600 14C yr BP. From 15,600 14C yr BP to present there is a substantial increase in arboreal elements and herbs, indicating more humid and warmer climate. From 19,000 to 1000 14C yr BP, δ13C values indicated the predominance of C3 plants. These results are in agreement with studies in speleothems of caves, which suggest humid conditions during the last glacial maximum. |
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| Keywords: | Southeastern Brazil Rainforest Carbon isotopes Soil organic matter Pollen Peat |
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