A 1.8 million year history of Amazon vegetation

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Kern, Andrea K. ; Akabane, Thomas Kenji ; Ferreira, Jaqueline Q. ; Chiessi, Cristiano M. ; Willard, Debra A. ; Ferreira, Fabricio ; Sanders, Allan Oliveira ; Silva, Cleverson G. ; Rigsby, Catherine ; Cruz, Francisco W. ; Dwyer, Gary S. ; Fritz, Sherilyn C. ; Baker, Paul A.

• Tipo de documento: Artigo Científico
• Fonte: QUATERNARY SCIENCE REVIEWS; v. 299, p. 18-pg., 2023-01-01.

Resumo

During the Pleistocene, long-term trends in global climate were controlled by orbital cycles leading to high amplitude glacial-interglacial variability. The history of Amazonian vegetation during this period is largely unknown since no continuous record from the lowland basin extends significantly beyond the last glacial stage. Here we present a paleoenvironmental record spanning the last 1800 kyr based on palynological data, biome reconstructions, and biodiversity metrics from a marine sediment core that preserves a continuous archive of sediments from the Amazon River.Tropical rainforests dominated the Amazonian lowlands during the last 1800 ka interchanging with surrounding warm-temperate rainforests and tropical seasonal forests. Between 1800 and 1000 ka, rainforest biomes were present in the Amazon drainage basin, along with extensive riparian wetland vegetation. Tropical rainforest expansion occurred during the relatively warm Marine Isotope Stages 33 and 31 (ca. 1110 to 1060 ka), followed by a contraction of both forests and wetlands until ca. 800 ka. Between 800 and 400 ka, low pollen concentration and low diversity of palynological assemblages renders difficult the interpretation of Amazonian vegetation. A strong synchronicity between vegetation changes and glacial-interglacial global climate cycles was established around 400 ka. After 400 ka, interglacial vegetation was dominated by lowland tropical rainforest in association with warmer tem-peratures and higher CO2. During cooler temperatures and lower CO2 of glacial stages, tropical seasonal forests expanded, presumably towards eastern Amazonia. While this study provides no evidence sup-porting a significant expansion of savanna or steppe vegetation within the Amazonian lowlands during glacial periods, there were changes in the rainforest composition in some parts of the basin towards a higher proportion of deciduous elements, pointing to less humid conditions and/or greater seasonality of precipitation. Nevertheless, rainforest persisted during both glacial and interglacial periods. These findings confirm the sensitivity of tropical lowland vegetation to changes in CO2, temperature, and moisture availability and the most suitable conditions for tropical rainforests occurred during the warmest stages of the Mid Pleistocene Transition and during the interglacial stages of the past 400 kyr.(c) 2022 Elsevier Ltd. All rights reserved. (AU)

• Processo FAPESP: 12/50260-6 - Estruturação e evolução da biota amazônica e seu ambiente: uma abordagem integrativa
• Beneficiário: Lúcia Garcez Lohmann
• Modalidade de apoio: Auxílio à Pesquisa - Programa BIOTA - Temático
• Processo FAPESP: 19/24349-9 - Avaliando os efeitos das mudanças climáticas do passado e do futuro na biodiversidade amazônica (CLAMBIO)
• Beneficiário: Cristiano Mazur Chiessi
• Modalidade de apoio: Auxílio à Pesquisa - Programa BIOTA - Regular
• Processo FAPESP: 18/15123-4 - Perspectivas pretéritas sobre limiares críticos do sistema climático: a Floresta Amazônica e a célula de revolvimento meridional do Atlântico (PPTEAM)
• Beneficiário: Cristiano Mazur Chiessi
• Modalidade de apoio: Auxílio à Pesquisa - Programa de Pesquisa sobre Mudanças Climáticas Globais - Jovens Pesquisadores - Fase 2
• Processo FAPESP: 14/05582-0 - Estruturação e evolução da biota amazônica e seu ambiente: paleobotânica e palinologia da Bacia Amazônica
• Beneficiário: Andrea Kern
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado
• Processo FAPESP: 15/18314-7 - Reconstituição das mudanças de vegetação nos últimos ciclos glaciais-interglaciais com base em registros polínicos de testemunhos marinhos na da costa oeste equatorial do Oceano Atlântico
• Beneficiário: Andrea Kern
• Modalidade de apoio: Bolsas no Exterior - Estágio de Pesquisa - Pós-Doutorado
• Processo FAPESP: 19/19948-0 - Influência das mudanças climáticas sobre a flora amazônica durante o Pleistoceno tardio
• Beneficiário: Thomas Kenji Akabane
• Modalidade de apoio: Bolsas no Brasil - Doutorado