The role of abrupt climate change in the formation of an open vegetation enclave in northern Amazonia during the late Quaternary

Author(s)

Zular, Andre ^[1] ; Sawakuchi, Andre Oliveira ^[1] ; Chiessi, Cristiano Mazur ^[2] ; d'Horta, Fernando Mendonca ^[3] ; Cruz, Francisco William ^[1] ; Melo Dematte, Jose Alexandre ^[4] ; Ribas, Camila Cherem ^[5] ; Hartmann, Gelvam Andre ^[6] ; Fonseca Giannini, Paulo Cesar ^[1] ; Amaral Soares, Emilio Alberto ^[7]

Affiliation

^[1] Univ Sao Paulo, Inst Geociencias, Rua Lago 562, BR-05508080 Sao Paulo, SP - Brazil

^[2] Univ Sao Paulo, Escola Artes Ciencias & Humanidades, Sao Paulo - Brazil

^[3] Inst Nacl de Pesquisas da Amazonia, Programa Posgrad Genet Conservacao & Biol Evolut, Manaus, Amazonas - Brazil

^[4] Univ Sao Paulo, Colegio Agr Luiz de Queiroz, Dept Ciencias Solo, Piracicaba - Brazil

^[5] Inst Nacl de Pesquisas da Amazonia, Coordenacao Biodiversidade, Manaus, Amazonas - Brazil

^[6] Univ Estadual Campinas, Inst Geociencias, Campinas, SP - Brazil

^[7] Univ Fed Amazonas, Dept Geociencias, Manaus, Amazonas - Brazil

• Document type: Journal article
• Source: GLOBAL AND PLANETARY CHANGE; v. 172, p. 140-149, JAN 2019.
• Web of Science Citations: 2

Abstract

The effects of climate changes on biotic expansion or divergence is a widely debated topic. This discussion is particularly relevant for northern Amazonia where patches of open vegetation environments that harbor high endemic and specialized species are present in a matrix of tall closed canopy forest. This paper presents the depositional chronology and evolution of an 8.7-m thick stabilized fluvial and eolian sediment profile in a sandy plain substrate that underpins the largest open vegetation enclave in northern Amazonia. Three depositional units were identified using optically stimulated luminescence and radiocarbon ages coupled with grain size, magnetic susceptibility, and reflectance analyses. A lower unit of coarse fluvial silt deposited between 53 and 28 ka is overlain unconformably by a 5-m thick middle unit of fine eolian sand deposited at high accumulation rates between the Last Glacial Maximum (23-19 ka) and Heinrich Stadial 1 (HS1; 18.1-14.7 ka) when persistent and long-lasting shifts of the Intertropical Convergence Zone (ITCZ) to the Southern Hemisphere promoted dry and windy conditions in northern South America. An upper similar to 2-m thick unit was deposited when the climate became wetter after HS1, promoting the formation of soils that support open vegetation habitats. This study indicates that abrupt millennial-scale climate events can induce significant changes in the Amazonian landscape, which in turn play an essential role in the distribution and diversification of specialized biota. (AU)

• FAPESP's process: 12/17517-3 - Response of the Western Atlantic Ocean to changes in the Atlantic meridional overturning circulation: from millennial to seasonal variability
• Grantee: Cristiano Mazur Chiessi
• Support Opportunities: Research Program on Global Climate Change - Young Investigators
• FAPESP's process: 16/02656-9 - The response of sedimentary dynamics of the Xingu and Tapajós rivers to climate changes and hydropower dams: risks for biodiversity conservation and energy production in Amazonia
• Grantee: André Oliveira Sawakuchi
• Support Opportunities: Research Program on Global Climate Change - Regular Grants
• FAPESP's process: 12/50260-6 - Structure and evolution of the Amazonian biota and its environment: an integrative approach
• Grantee: Lúcia Garcez Lohmann
• Support Opportunities: BIOTA-FAPESP Program - Thematic Grants
• FAPESP's process: 11/06609-1 - Provenance, transport and storage of sediments in Amazon rivers
• Grantee: André Oliveira Sawakuchi
• Support Opportunities: Regular Research Grants