FLORISTIC CHANGE AND DIVERSITY USING FOSSIL MACROFLORA FROM EARLY PALEOGENE (CA. 59-50 MA) ARCTIC RAINFORESTS

The early Paleogene experienced significant climate warming, with the occurrence of 3 major hyperthermal events during the late Paleocene to early Eocene (PETM/ETM1, ETM2, and EECO). These rapid warming events have been associated with the release of massive amounts of CO₂ and other greenhouse gases into the atmosphere and were coupled with orbital changes. This occurred over short time intervals and resulted in global changes in temperature and precipitation, with the greatest changes occurring at high latitudes, including changes in seasonality. These changes in climate caused a decreased latitudinal temperature gradient which would have had an impact on the composition of regional vegetation, particularly in the Arctic. The Eocene hyperthermal events are therefore analogous to modern anthropogenic global warming. The warm environments of the early Paleogene extended well into high latitudes, and for much of the early Paleogene the Arctic was inhabited by a lush swamp forests of cedars, redwoods, pines, and deciduous dicots, and with reptiles such as alligators that are now confined to low and mid-latitudes. Few studies have investigated the diversity or change in composition of these early Paleogene Arctic forests. These prior studies showed that the Arctic flora was not only endemic to the region, but of similar richness to modern day forests from middle latitudes; however, these studies were based primarily on pollen analyses and so may include a landscape to regional as opposed to local environmental signal. Presented here is an analysis of floristic change and diversity of Arctic vegetation using 9 fossil macrofloras spanning the late Paleocene to middle Eocene (approx. 59-50 Ma) of the Eureka Sound Group (Mount Moore, Margaret, Iceberg Bay, and Buchanan Lake formations) from Axel Heiberg and Ellesmere islands of the Canadian Arctic, Nunavut. These floras are analysed based on a refined stratigraphy to better reflect temporal shifts associated with hyperthermal events.