Australia

Recent large, deadly bushfires during the “Big Dry” in southeastern Australia figure prominently in the Australian Government’s conclusion that climate change is occurring faster and has more serious consequences than previously believed. The same report notes that the link between climate change and bushfires is multi-faceted and complex because bushfires are influenced by many factors including the amount and condition of the fuel load, land-cover patterns, non-native plant invasions, extreme weather events, ignition sources, and management practices. Tasmania is an ideal area for examining human and climate influences on wildfire activity because (a) the landscape is made up of a mosaic of fire sensitive vs. highly fire tolerant plant communities, and it displays strong east-west contrasts in the history of European settlement and current land-use patterns, (b) long-lived (1000 years) trees with proven dendrochronological potential can yield annual-resolution tree-ring fire histories, (c) numerous small lakes offer the potential for high resolution charcoal records, and work can be tied to previous and ongoing paleoecological investigations, (d) previous research provides a broad understanding of vegetation responses to recent and past fire and climate variations and land-use history, and (e) Tasmania is but one area of interest for our Australian colleagues and their work in other Australian settings invite comparison and extend our reach.

In 1968, W.D. Jackson proposed a comprehensive model of how Tasmanian vegetation types, fire frequency and soil fertility interacted in a complex system of feedback loops, resulting in self-reinforcing vegetation patterns. This theory profoundly influenced the subsequent course of fire ecological research far beyond Tasmania. In WildFIRE PIRE, we will examine aspects of Jackson’s theory that are fundamental to predicting how vegetation will respond to future climate-induced changes in fire activity. Fire is considered a primary driver of vegetation dynamics in Tasmania. Tree-ring and lake-sediment fire-history research has not previously been conducted in Tasmania. Climate-vegetation linkages can be studied on multiple temporal and spatial scales and across scales. 

WildFIRE PIRE research in Tasmania seeks to develop a network of sedimentary charcoal and tree-ring fire records over the past 10,000 years. It will also link with research underway investigating human-fire-climate linkages in temperate and tropical Australia. Our specific contribution will be to:

  • Reconstruct landscape-scale fire activity at an annual resolution over the last 1000 years from tree-ring records of fire, tree death, and stand establishment dates. This effort will target fire-killed stands of Athrotaxis trees throughout the species’ geographic range as well as drier forest types.
  • Obtain fire, vegetation, and climate data for the last 5000 years, based on charcoal and pollen records from 5-6 small lakes within watersheds where tree-ring fire histories are underway, and in watersheds where archeological data suggest greater prehistoric human activity. This approach will extend the fire, vegetation, and climate information back in time and across the east-west environmental gradient.
  • Explore the influences of major climate and modes of climate variability (indexed as sea-surface temperature variations) on current and past fire activity to better understand fire-climate linkages, independent of human activities.