Wed. Oct 27th, 2021

Selective harvesting in state forests on the NSW North Coast does not adversely affect koala numbers, a three-year research program has found — to the indignation of a forest conservation group.

But the state’s spearhead body says the results justify foresters.

As part of the research, which was overseen by the State Natural Resources Commission (NRC), an independent government body, acoustic sensors were set up in 2019 to monitor koalas in state forests and control sites in national parks.

When researchers from the NSW DPI Forest Science Unit returned after harvest last year, they found no difference in koala numbers.

“We do the work in the spring, it’s the koala growing season, and that’s when the males bellows to attract females and also to advertise themselves to other males,” said Dr. Brad Law.

“We put these recorders out at a distance of 400 meters in a grid and we let them stand out in the woods for two weeks and record all night continuously.

Brad Law in the woods with an acoustic sensor.
NSW DPI forestry researcher Dr. Brad Law with an acoustic sensor used to detect koala cold in forests.(Delivered to: NSW Department of Primary Industries)

“Our places are very large … about 400 acres in size, and it varied from place to place, but on average it’s about 0.05 koalas per acre, so that means about one koala per 20 acres.”

To find horror conservation group

The North East Forest Alliance’s Dailan Pugh has labeled the finding that deforestation does not affect koalas as “dangerous propaganda” that further threatens the species’ survival, and he questions Dr. Law’s research.

Koala with baby on the tree.
Research using sound sensors found that there was no change in koala numbers before and after selective logging.(Delivered: Ian Brown, Science for Wildlife)

“The recorder will say, ‘Yes, we have a male koala calling somewhere near this recorder,’ and the recorder may be over a mile away and it does not tell you how many koalas there are. in the woods, said Mr. Pugh.

“They have extrapolated it to claim that if you had a koala calling somewhere within a mile before an area was logged, and they called again somewhere in the vicinity after it was logged, it shows, that logging has no bearing.

“That koala could have been somewhere in an unlogged patch far away from where the actual logging took place, there could have been a whole bunch of koalas in that area before and only one after.”

A man with a large white beard wears a knitted sweater in front of trees.
Dailan Pugh is outraged at the report’s discovery that selective harvest does not affect koala numbers.(ABC North Coast: Margaret Burin)

The Natural Resources Commission’s CEO Bryce Wilde has defended the results of the research program.

“It was managed by an expert panel that we drew together, and we had an extensive process of selecting the researchers and then quality assured, the work has been thoroughly peer reviewed and is up for review,” he said.

Nutritional quality of trees is critical

ANU Fellow Dr. Karen Ford sampled leaves from 900 trees of 22 different eucalyptus species in nearly 60 locations.

Dr.  Karen Ford in a Forest.
ANU Fellow Dr. Karen Ford says the nutritional quality of the trees is crucial to koala survival.(Delivered: Dr. Karen Ford)

Blackbutt, an important timber species, proved to be one of the lowest nutritional quality species.

“If you change the composition of the wood of the forest by increasing the proportion of koala -browse species, you get an increase in the nutritional quality of the forest, and if you change it by increasing the amount of blackbutt in the forest than you get a decrease in the nutritional value of forests for koalas, ”she said.

The study found that if there were too many non-browse species, there could be a decline in the number of koalas in the forest.

A man sits on the ground and puts leaf samples in a bag.
ANU research assistant Ivan Kotzer collects magazines to take to the laboratory for analysis.(Delivered: Dr. Karen Ford)

Finds ‘justify’ foresters

Timber NSW’s CEO Maree McCaskill said the results decided without a doubt that koalas could coexist with selective harvesting.

Blackbutt Forest on the Coffs Coast.
ANU research found that black nut had a much lower nutritional quality than other species, including tallow, small fruit gray chewing gum and swamp mahogany.(Delivered: NSW EPA)

“I’m not saying the forests are completely out of the woods by any means … and I think that after fires, there is still a significant amount of work to be done.”

The NRC also found that more research was needed on koalas’ response to intensive harvesting practices, and that climate change and the increased risk of wildfires posed greater risks to their long-term survival.

Wilde said the research looked at how koalas were recovering from the devastating forest fires of Black Summer 2019-2020.

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“In the areas where the fires were moderately severe, research shows that there was a reduction in detection rates of about 50 percent, but that subsequently koalas are returning, and there are koalas returning to these places.”

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