National Socio-Environmental Synthesis Center (SESYNC)
1 Park Place, Suite 300
Annapolis, MD 21401
Title: Climatic and Human Influences on South American Extinctions, Microrefugia, and Tipping Points
Seminar presented by Mark Bush, Florida Institute of Technology
Abstract: Quaternary climate change has continuously stirred the pot of Andean species distributions. Fossil pollen, spores and charcoal from lake sediments, provide long time-series in which we can see local ecological responses to changing conditions. Ice ages forced some species downslope by 1500 m relative to modern distributions, whereas other species may have responded much less. In contrast the last interglacial (c. 128,000-115,000 years ago) was hotter and drier than today, with obvious relevance for what we may face in the future. Both glacials and interglacials of the past differed markedly in their strength and in how they influenced biota. I will present ideas on the biotic consequences of interglacials that were more or less extreme than those of today, and how they led to an Andean tipping-point. I will discuss how the existence of microrefugia, isolated microcosms where species could persist amid general adversity, adds to our understanding of the individualistic responses and migrational ability of species in light of climate change. I will provide some data that shows the complex history of megafaunal population collapse at the end of the Pleistocene and how this extinction was probably a synergy between climate change and humans hunting. A common thread running through the presentation will be the transformative potential of fire, and its history before and after the arrival of humans. I will end by looking at the risk of revisiting a tipping point.
Bio: Mark Bush is a palaeoecologist and biogeographer with more than 30 years' experience of Neotropical palynology and limnology. He obtained his BSc and PhD from the University of Hull (1986), before spending time at The Ohio State University, Smithsonian Tropical Research Institute, and Duke University. He is currently Professor of Biology at the Florida Institute of Technology. His research often sits at the nexus of biogeography, ecology, paleoclimatology, and archaeology. His current research areas include: the Quaternary interglacial history of the Andes; the causing and timing of megafaunal extinctions; the history of ENSO and its impacts on South American ecosystems; and the impacts of pre-Columbian peoples on the Amazon and the Andes.