Tough times ahead for eucalypts

A study published today (Tuesday 20 September) in Nature Climate Change concludes that global warming of three degrees Celsius over the next 60 years would see the majority of eucalypt species suffering significant habitat loss.

Of more than 700 species in the study, 91 per cent would lose about half their range on average, with 16 species left with no suitable habitat at all, and just 9 per cent of species having the potential to expand their range.

The study was led by Drs Carlos González-Orozco and Bernd Gruber from Canberra’s Institute for Applied Ecology, and included researchers from CSIRO, the University of Melbourne and the University of California, Berkeley.

Dr Andrew Thornhill, an adjunct Research Fellow at the Australian Tropical Herbarium (ATH) at James Cook University (JCU) in Cairns, worked on the project in Australia and in his current role at the University of California, Berkeley.

“Eucalypts were the perfect subject for this study because the group is so widespread, so diverse, and so important in Australia,” he said.

“They’re found in just about every environment in the country and there are parts of Australia that are almost impossible to visualise without eucalypts.”

The study uses phylogenetic (DNA) analysis in an approach that involves examining the fate of not just individual species, but whole lineages or branches on the tree of life.

It also identifies potential refuges that could help improve the odds for our embattled icons.

Dr Thornhill gathered DNA from the leaves of many hundreds of eucalypt species for the study, which crunched the numbers of more than 260,000 geospatial data points from herbarium records stored in Australian institutions such as the Australian Tropical Herbarium based at JCU.

“Thanks to Dr Laura Pollock at the University of Melbourne and now based at the University of Grenoble in France, and Nunzio Knerr from CSIRO, we were able to model the distribution of 657 species at a very high level of detail across the continent, and predict where they would occur in 70 years time, given different degrees of temperature increases” Dr Thornhill said.

The Director of the Australian Tropical Herbarium and President of the Australasian Systematic Botany Society, Professor Darren Crayn, said the study would not have been possible without decades of work by scientists and technicians in Australia’s herbaria and botanic gardens.

“This is ‘big data botany’, and it’s possible thanks to Australia’s world leadership in digitising the information held in our herbaria, which are scientific collections of preserved plant specimens, and doing that in ways that make it accessible and shareable,” he said.

“Thanks to publicly accessible resources like the Australia’s Virtual Herbarium and the Atlas of Living Australia, researchers are able to access massive amounts of data about our flora, making this kind of nation-wide, complex analysis possible.”

Dr Thornhill said the study would help focus habitat conservation efforts on those areas that contain the greatest genetic diversity, as well as identifying those areas that will become potential refuges as our climate changes.

“In the past couple of years we have developed methods to pinpoint the refuges – the places where the genetically oldest parts of the family tree, which might once have been more widespread, are still represented.

“We can also identify those areas that are the cradles, where relatively new species have developed, as well as those places that are both refuges and cradles, rich in both ancient and newer lineages.

“In this study we have looked into an uncertain future and identified the areas that could become future refuges. These warrant protection – to provide habitat not just for single charismatic species, but for significant parts of the family tree of our iconic eucalypts.”

Another study led by Dr Thornhill and published in the Journal of Biogeography in May this year confirmed that Cape York Peninsula and the rainforests of the Wet Tropics are outstanding areas of significant biodiversity, rich in both ancient and recently evolved lineages. This ‘grand-scale’ study used data from 3.4 million digitised Australian herbarium specimens and a phylogeny representing over 1800 flowering plant genera.

“It established quantitatively for the first time that northern Australian landscapes are critically important for the preservation of Australia’s botanical evolutionary heritage,” Professor Crayn said.

Media enquiries: linden.woodward@jcu.edu.au