Palaeoecological Analyses Reveal Recent Fires Have Destroyed Late-Holocene Peat Deposits in Tasmania's Largest Ramsar Reserve

Abstract

Australian peat-forming wetlands are some of the most biodiverse in Oceania. King Island, the second largest offshore island from mainland Tasmania, has the largest Ramsar-wetland area in Tasmania—the Lavinia State Reserve (LSR). The reserve has been under threat of peat loss from swamps over past decades due to wildfires, deforestation and drainage. To provide a framework and baseline to assess the resilience or susceptibility to future climate change and fire impacts at the LSR, we apply a palaeoecological approach to understand Holocene peat dynamics in two different LSR wetlands. This contributes to resolving the dynamics and rate of peat loss, thereby assisting in prioritising areas for further swamp conservation actions. Both LSR wetlands were once lakes, and peat accumulation only started due to terrestrialisation during a period of low water levels and drought in the Mid-Holocene. Fires have resulted in the loss of at least 4000 years' worth of accumulated peat in the largest peat-forming swamp, with the greatest loss likely linked to summer fires in the LSR in the 2000s. This finding shows the long-term vulnerability of the LSR wetlands to climate and fire impact, underscoring the need for effective fire management to conserve the remaining peat through fire control and careful hydrological management.