Rainforest response to glacial terminations before and after human arrival in Lutruwita (Tasmania)

Limited understanding of how Indigenous people have created and managed the Australian landscape continues to have repercussions on how landscapes are culturally interpreted and managed today. Addressing this is critically important as climate change is increasing the frequency and intensity of wildfires, whilst challenging the objectives, methods and efficacy of contemporary landscape management practices. Here we compare the palaeoecology of vegetation changes across glacial to interglacial states before (Termination II) and after (Termination I) human occupation of the cool temperate rainforests of western Lutruwita (Tasmania). Sediment from Darwin Crater (Termination II) and Lake Selina (Termination I) were analysed using radiometric dating, fossil pollen, charcoal, geochemical, environmental magnetic and sedimentary methods to produce a comprehensive reconstruction of vegetation and landscape dynamics. Results show marked differences in the rainforest response to the transition from glacial to interglacial climates before and after human arrival at c. 43,000 years ago (ka). In the absence of human disturbance, Phyllocladus aspleniifolius-Nothofagus cunninghamii lowland rainforest taxa dominated the last interglacial period (∼77% of the pollen sum) but was reduced in the current interglacial (∼41%) and largely replaced by Gymnoschoenus sphaerocephalus buttongrass moorland (10–23%). This demonstrates the legacy of Indigenous Palawa managed landscapes, primarily using fire to promote landscape openness and prevent the dominance of an ecologically climax rainforest community, until their forced removal via invasion and colonisation ca. 1806.

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