North-western Tasmania is home to one of the world's last remnants of primeval temperate rainforest, part of an ecosystem that once spread across the supercontinent of Gondwana. Thousand-year-old trees tower above ancient ferns, their roots growing in peat accumulated over millennia. This is why the region has been designated a UNESCO World Heritage Site. Eucalyptus forests in the rest of Australia need fire to regenerate. But these plants evolved before the cycle of conflagration and renewal began. If they burn they die.