Interactions between Climate, Megafauna, Human and Fires in Western Amazonia

Abstract

South America, and more specifically Western Amazonia has a lack of data regarding ecosystem changes that have occurred over the last 30,000 years. Even though ecological changes during the Late Pleistocene have been documented, including ice-age plant migrations and the extinctions of 80% of megafauna species at continental scale, there is uncertainty on the role that fire has played in these ecosystems. Controversy exists over fires natural role in parts of Amazonia, as high humidity and precipitation are thought to supress natural fires. This has created an assumption that fire in Western Amazonia occur largely a result of anthropogenic activities. This study aims to gain a deeper understanding of the interactions between climate, fire activity, megafauna, and humans in Western Amazonia. This research is the first attempt to investigate the impacts of fire activity and Megafauna extinctions from a hotspot of biodiversity in Western Amazonia: Lake Consuelo. By analysing microparticles of charcoal, spores of Sporormiella and the pollen record this research aims to detect the changes in: fire activity, megafauna presence and vegetation changes over the last 28,000 years. The results showed that fires have occurred since the Late Pleistocene (28,0000 years ago) and thus have been a natural feature of this ecosystem. It was also found that megafauna survived into the Mid-Holocene, suggesting that Lake Consuelo may have provided a refuge for megafauna. Lake Consuelo remained forested and relatively humid during the Mid-Holocene; a period known to be as pervasively dry in Western Amazonia. Lake Consuelo’s ecosystem showed to be highly resilient to the changes in climate, fire activity, and megafauna with a relatively high degree of environmental stability throughout the past 28,000 years. Given the high biodiversity concentration found in Western Amazonia, long-term understanding of ecosystem functioning in this region is vital to manage and conserve this biodiversity in the future. As unprecedented climate change and rapid population increases are predicted, areas like Lake Consuelo may be crucial to preserve high biodiversity levels if managed appropriately.