This season's bushfires damaged Gondwana rainforests, including trees with lineages dating back tens of millions of years, placing at risk the highest concentrations of threatened species in NSW.

Robert Kooyman, an ecologist and honorary research fellow at Macquarie University, said the unprecedented fires in northern NSW had likely killed at least 10 per cent of the world's only wild stand of nightcap oak.

Bushfires in Gondwanan rainforests of northern NSW have placed many threatened species at risk, ecologists say. Credit:Mark Graham

Other endangered species such as peach myrtles - possibility the oldest organisms on the planet with the "immortal clones" living a thousand years or more - and minyon quandongs were also badly hit, he said.

"We have serious issues in this forest," said Dr Kooyman, who discovered and documented the nightcap oak two decades ago. "Recovery action will need to be planned very carefully, and given a reasonable amount of funding."