A 1.8 million year history of Amazon vegetation

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 lowland basin extends significantly beyond last glacial stage. Here we present a paleoenvironmental spanning 1800 kyr based on palynological data, biome reconstructions, and biodiversity metrics marine sediment core that preserves archive sediments Amazon River. Tropical rainforests dominated lowlands ka interchanging with surrounding warm-temperate tropical seasonal forests. Between 1000 ka, rainforest biomes drainage basin, along extensive riparian wetland vegetation. expansion occurred relatively warm Marine Isotope Stages 33 31 (ca. 1110 1060 ka), followed contraction both forests wetlands until ca. 800 ka. 400 low pollen concentration diversity assemblages renders difficult interpretation A strong synchronicity between changes was established around After interglacial association warmer temperatures higher CO2. cooler lower CO2 stages, expanded, presumably towards eastern Amazonia. While study provides evidence supporting significant savanna or steppe within periods, there composition some parts proportion deciduous elements, pointing less humid conditions and/or greater seasonality precipitation. Nevertheless, persisted periods. These findings confirm sensitivity CO2, temperature, moisture availability most suitable for warmest stages Mid Pleistocene Transition past kyr.