TAS-3: Flinders Island
Title: Reconstructing human-climate-fire interactions on Flinders Island
Investigators: McWethy, Haberle
Opportunities for intern participation: possible opportunity for intern participation in fieldwork YR3.
Objectives: Throughout much of the world, it is difficult to disentangle the impact of human activities and climate change on past fire regimes. This is especially true in environments with a long history of both fire and human presence, where separating the influence of humans and climate on fire regimes requires detailed reconstructions of past climate and fire along with proxies of human presence. In Tasmania, where humans have been present for over 30,000 years, research suggests that human-climate-fire interactions are strongly coupled (Fletcher and Thomas, 2010). Archeological data from Flinders Island in the Bass Strait between mainland Australia and Tasmania suggest an absence of human presence from c. 4700 to 200 BP. The absence of humans during this extended period provides a unique opportunity to evaluate both climate and human influence on fire and vegetation. Ladd et al. (1992) reconstructed past vegetation and fire history for Flinders Island from pollen and charcoal data collected at two wetland sites. Pollen data indicate a transition from steppe vegetation to Eucalyptus c. 6000 BP followed by a decline of Eucalyptus concurrent with an increased presence of Callitris c. 940 BP. Ladd et al. (1992) found little evidence of strong human influence on these vegetation transitions or changes in fire activity but the resolution of analyses was coarse. We propose to collect 3-4 peat or lagoon sediment cores for high-resolution charcoal, pollen and geochemical analyses to determine how climate and the presence, then absence, of humans on Flinders Island interacted to shape vegetation and fire on the island. Our objectives are to (1) reconsider the extent of human influence on patterns of fire and vegetation transitions in a fire-prone ecosystem through high-resolution peat and lagoon- sediment analyses; (2) determine whether the presence/absence of human activities contributed to limnobiotic and geochemical changes to watersheds on Flinders Island; and (3) better understand the ecological response to human impacts in a setting where vegetation evolved with fire. This examination provides a good comparison for the questions raised in PIRE NZ-2, given the contrasting fire history of South Island, New Zealand.
Work Plan: We will select 3-4 wetland/lagoon sites to collect cores for high-resolution pollen charcoal, limnobiotic and geochemical analyses. This work will be undertaken by McWethy and Haberle.
Related Activities – Associated Funding
Research will complement efforts by Haberle, Bowman, Fletcher, Higuera, Veblen, and Whitlock to better understand the role that humans played in altering fire regimes and vegetation dynamics in Tasmania. Year 2 research will be partially funded by NSF grant (BCS-1024413; McWethy and Whitlock).
High-resolution pollen, charcoal, and geochemistry records to reconstruct the vegetation, fire and watershed history of Flinders Island for the past 10,000 years. The results will be published with McWethy and Haberle as lead authors and the data will be used in other synthetic activities.
Year 2 Update
This project examines the fire history of Flinders Island, which archeological data suggest early occupation by Aborigines ended about 5000 years ago and, thus, the island had no human presence until European arrived in the 19th century. Understanding the long-term recovery of the vegetation in the absence of anthropogenic burning is an important component of understanding the importance that people might have had in shaping or modifying prehistoric fire regimes. Sediment cores were recovered from 23 lakes and wetlands during a two-week field campaign. We anticipate that two sites have records that span the entire Holocene period and the remaining sites will provide information on the last few thousand years. Some cores were sent to Australian National University for diatom and charcoal analysis in Haberle’s lab. The remaining cores were sent to University of Minnesota for initial core descriptions, density scanning, high-resolution magnetic susceptibility and high-resolution imaging. Preliminary sampling of the second set of cores for pollen, charcoal, and radiocarbon dating is just beginning at the MSU Paleoecology Laboratory as Year 3 activity.