In short:
A severe lack of rain in parts of SA, Victoria and Tasmania in the first half of 2024 leads to increased reports of dead and stressed native trees and bushes.
A botanist says this is becoming more common as these regions warm up and rain arrives later in the year.
What’s next?
Late winter and spring rain could see some trees and shrubs bounce back, but others may be too stressed and starved to recover.
As farmers report high numbers of dying and distressed native trees and shrubs, a botanist is warning of the potential for “devastating” losses.
A record dry autumn across southern parts of Australia saw parts of the country record record-low rainfall for the first half of 2024.
Farmer Andrew Smith noticed dying trees and wattle bushes after the driest June-July on record at his 810-hectare sheep property at Laura in South Australia’s Mid North.
“We’re seeing a big thinning event of some of our native trees, particularly the blue gums and sugar gums on the tops of ridges,” Mr Smith, whose property borders a conservation park, said.
“A lot of the new ones which are only 10 years old [are dying] but also, we’re seeing trees that are 50 years plus dying because they haven’t seen this type of dry.
“The soil’s not that deep, there’s no water table to tap into and less than 200 millimetres of rain in 12 months is just not enough for them.”
Concerns for fire risk
While some recent rain was welcomed, with more expected into spring, Mr Smith is worried about the next fire season.
“We’ve got patches of lots of dead foliage and gum trees, and we don’t have a lot of hope that it’s suddenly going to be green,” he said.
“There’s a lot of vegetation that could be flammable as early as Christmas.
“I’ve got goats to help reduce the fuel load to a fair extent, but it could be an interesting fire season.”
Dry conditions widespread
University of Melbourne botanist Gregory Moore said there were widespread reports of native species dying off this year.
“It’s happening in quite a number of places, SA and Victoria, but also parts of Tasmania, so it’s been a sort of reasonably common observation in the last maybe three to six months,” Dr Moore said.
“What most of us are seeing at the moment is that the soil is dry, the plants have been stressed, and the root systems start to starve.”
Dr Moore said while Australian natives were resilient and well-adapted to harsh conditions, recent seasonal changes led to more dying out.
“It’s often becoming a bit warmer in these places,” he said.
“It’s drier and when the rain falls, it’s sometimes falling in the drier months, so that water evaporates as well.
“So you’ve got this sort of combination of factors … and you can get this acute response, which is a very rapid sort of collapse of the tree, and that’s from embolism.
“But you also get this slightly slower response where trees die over a period of weeks or months, literally from starvation of the root system.
“If you start seeing trees where parts of trees or whole trees die with the leaves still on, that’s a sign of a really serious stress, and that’s what we’re seeing more of.”
Survival uncertain
Dr Moore said many eucalypts could bounce back when rain arrived, but that was not guaranteed “if they’re near starving”.
“It is very, very concerning,” he said.
“Some of these losses could be devastating because when you lose the remnant vegetation that you’ve got, it’s not only that species that you that you lose, you lose all the other species that are associated with it.
“You might have 50 to 100 other species or organisms that depend on that particular species so if you lose it, you’re not just losing a tree, you’re starting to lose an ecosystem.”
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