By Sophie Aubrey
Next to the fallen trunk of the Royal Botanic Gardens’ 150-year-old white oak now stand three saplings that have come all the way from the sunny climes of California, Mexico and Texas.
The three young oak trees, about three metres tall and just coming into leaf for spring, will look slightly different to the older trees on Oak Lawn: the loquat leaf oak has rougher leaves without the classic lobes, the water oak’s leaves are narrower and the valley oak’s are smaller with deeper lobes.
But botanist Tim Entwisle, the gardens’ chief executive, said they were carefully selected as acorns from warmer parts of the world so that they would survive Melbourne’s changing climate. In 2090, the city’s temperatures are projected to be more like present-day Dubbo.
The 150-year-old white oak collapsed in 2019 in part due to climate change, Entwisle said, with some of the tree being left in place to encourage reflection.
The project is just an example of what Entwisle’s team will be doing much more of to safeguard the gardens’ future.
This week, the gardens are launching a Climate Assessment Tool that will allow botanic gardens around the world to punch in their location and work out which of the globe’s more than 60,000 tree species will tolerate its end-of-century climate.
Entwisle said the program compared a tree’s preferred temperature range to a location’s projected temperatures and issued a rating based on whether the plant would struggle or flourish.