Late Quaternary vegetational and climatic changes in Brazil

Abstract

Brazil comprises about 50% of the South American continent including prominent ecosystems like the Amazon and the Atlantic rain forests, semideciduous forests, cerrado, Araucaria forests and campos (grasslands). Detailed palynological studies on new sediment cores located on a transect from southern to northern Brazil allow a regional reconstruction of late Quaternary vegetation and climate history. This paper presents an overview and a paleoclimatic synthesis based on 10 paleoecological records from Brazil. Several changes within different vegetation types and shifts of vegetation belts during glacial and Holocene times were found. Pollen records from the south Brazilian highlands demonstrate that campos vegetation extended from glacial to early Holocene times which was replaced by Araucaria forests only during the late Holocene. Records from the southeast Brazilian lowlands and highlands show a replacement of modern tropical semideciduous forests and cerrado vegetation by subtropical grasslands and gallery forests during the last glacial period, indicating a relatively dry climate with a longer annual dry season and a cold climate with frosts. Some areas of cerrado were replaced by semideciduous forests in southeastern Brazil only in the last millennium. During the early Holocene a longer annual dry season is found in southern and in southeastern Brazil. The latest Holocene period is the wettest since the Last Glacial Maximum for which the shortest dry season has bee inferred. Pollen records near the Amazon mouth indicate palaeovegetation of non analog composition and changes in Amazon rain forest during the late-glacial and early Holocene. Evidence of Podocarpus pollen indicates cooler conditions during the late-glacial.