MOST southern hemisphere plants – except for weeds – will not be able to adapt to rapid climate change, a study of more than 11,000 species suggests.

Researchers, including the Sydney botanist Peter Weston, traced the history of plants that live in a range of different habitats including bogs, alpine regions, rainforests and arid environments.

They found the vast majority were still stuck in their old ways. Despite tens of millions of years of evolution, less than 4 per cent of the species had managed to shift to new habitats.

“We were struck by the conservatism of plants – how rarely they were able to adapt and flourish outside of their ancestral environments,” said Dr Weston, of the Botanic Gardens Trust.

This made it likely that many species would have trouble surviving if their current habitats shrank as a result of climate change, he said.

Those least likely to go extinct were plants with short life cycles and that spread easily – both characteristics of weeds.

“Weeds will be the beneficiaries of climate change,” Dr Weston said.

The international team, which included Mark Westoby of Macquarie University, studied a wide variety of plants such as grasses, legumes, conifers and cycads from six regions including Australia, New Zealand, Africa and South America.

The Australian National University biologist Mike Crisp, who led the team, said the species covered represented about 15 per cent of the total plant life, making the study, which is published in the journal Nature, the largest of its kind.

Where species had managed to shift out of their ancestral habitats this had tended to be into habitats that had opened up in the past 25 million years, such as arid areas and temperate grasslands, Professor Crisp said.