Holocene environmental dynamics in coastal, eastern and central Amazonia and the role of the Atlantic sea-level change

Abstract

2drainage area which is larger than Europe. Because of its huge area, Amazonia plays a significant role in the establishment of global climate, water and carbon budget (e.g. Saint-Paul et al. 1999). Amazonia is mostly covered by rainforest and some savanna ecosystems. The Amazon Basin is low lying with >1,000,000 km 2 at <100 m elevation. For much of its course, the Amazon has a grade of 1 in 100,000. The water level in Manaus, which lies 1200 km inland is only 14 m a.s.l. (Grabert 1991). As a consequence, in the eastern half of the basin the development of rivers and lakes is strongly influenced by Atlantic sea-level fluctuations. The amount of annual rainfall as well as the sea-level dynamics influence the occurrence of seasonally inundated forests, which form an area of up to 700,000 km 2 (Pavia 1995). Also Amazonian coastal ecosystems such as mangroves and salt marshes are a result of sea-level fluctuations. In order to understand past environmental changes in Amazonia such as the natural amplitude of Amazonian ecosystem dynamics, including coastal ecosystems such as mangroves, as well as Amazonian river and climate changes, palaeoecological and palaeoenvironmental studies are important. Several lacustrine and mangrove sediment deposits have been studied by pollen analysis. The aim of this paper is to compare and summarise recently published pollen records and to give an overview of natural environmental changes in the coastal and Amazon Basin region, related to the impact of the Holocene sealevel changes. Tectonic movements/subsidence may have played a certain role as well, but will be not considered in this study.