Long-term environmental change in eastern Tasmania: Vegetation, climate and fire at Stoney Lagoon

摘要

Tasmania's dry, inland east is ideally positioned to inform models of late Quaternary environmental change in southern Australasia. Despite this, it remains poorly represented in the palaeoecological record. Here, we seek to address this with a >13,000-year vegetation and fire history from Stoney Lagoon, a site at the eastern margin of Tasmania's inland Midlands plains. Pollen and charcoal analysis indicates that here, a relatively moist early deglacial was followed by a dry later deglacial (ca. 14,000-12,000 cal. BP), when sclerophyll forests became well established and burning increased. This suggests that the Midlands' vegetation responded to the climatic signals characterising Australia's south-eastern coast rather than those governing developments in western Tasmania. Dry sclerophyll forest persisted throughout the Holocene; with a pronounced transition from more to less grassy understoreys between ca. 9000 and 7000 cal. BP. From the mid-Holocene, the sclerophyll community remains relatively stable. However, increased fire activity and trends in moisture-sensitive taxa suggest generally drier conditions coupled with greater hydroclimatic variability under the strengthening influence of the El Nico-Southern Oscillation (ENSO). Overall, these results highlight the role of macro-scale climatic shifts in shaping vegetation development in Tasmania's inland east, while hinting at the concurrent importance of local ecological drivers. This highlights the need for spatially diverse studies to understand interactions between drivers of long-term environmental change in sub-humid southern Australia. This research also supports conservation by strengthening understandings of pre-colonial baselines in this highly modified landscape.