| dc.description.abstracteng | The biodiverse Amazon rainforest biome is the world’s largest rainforest ecosystem
and plays an essential role for global climate, carbon budget, and the hydrological
cycle. In the light of future climate change the effects of rising temperatures and changing precipitation on Amazonian biodiversity is a major point of interest. In
addition to climate change forest fragmentation is one of the biggest threats the Amazonian rainforest has to suffer, besides the growing pressure of human land use. In which way future global warming would induce species extinctions and ecosystem turnovers is therefore an important issue for future conservation strategies, which are based on a profound knowledge of species responses to predicted changes. Palaeoecological studies are an essential tool at this point, as they provide insights into connections between past climatic changes and the ecological response over long time scales. As long-term data for evironmental
history of Amazonia are still rare, this study contributes to a deeper knowledge of Amazonian vegetation and fire history. For this purpose it comprises a time frame of
around 70,000 years which includes the late Pleistocene, the Last Glacial Maximum (LGM), and the complete Holocene. The focus of this study lies on boundary areas in the south of the Amazon basin as these regions are particularly sensitive to climate change. Two investigated records from southeast Amazonia, situated in the Serra Sul dos Carajás in the state of Pará (Brazil) show that the ecosystems mainly depend on the general amount of precipitation during the late Pleistocene and to the characteristics of rainfall seasonality since the beginning of the Holocene. In adaption to ecological and climatological changes vegetation systems in Carajás mainly reacted with a changing species composition. Hence, under drier climates a formerly humid rainforest changed into a more open forest adapted to drier conditions, and also savannas expanded in the studied area, though never replaced forest completely. The amount and timing of precipitation, and hence ecosystems in southeast Amazonia, show a tight connection with temperature fluctuations in the tropical Atlantic. Results from a lacustrine record of Lago Amapá in southwest Amazonian Rio Branco (Acre, Brazil) show that the recorded opening of forests in the past 650 years occurred under mainly humid conditions and was strongly influenced by humans of pre- and post-Columbian settlements. | de |