Why Our Trees are Dying

BIG swathes of forest from Perth to the South-West – the size of 50 Kings Parks – have died from drought and may never recover, scientists warn.

And they say the dying trees are fuelling “plague proportions” of destructive insects, which are invading the area in record numbers.

Meanwhile, food and water resources are drying up for native mammals, with studied fauna weighing 30 per cent less this year than last.

Aerial and ground surveys of WA‘s northern jarrah forest reveal that 20,000ha of ecosystem has collapsed, while other areas are on the verge of failure.

WA’s Centre of Excellence for Climate Change Woodland and Forest Health, which has been monitoring the forest from the Perth Hills to York and south to Collie since January, warns that the finding is the tip of the iceberg.

Centre director and ecologist Giles Hardy said the face of the Perth Hills was changing. Big trees some hundreds of years old were likely to become a thing of the past in some areas.

About 6 per cent of the jarrah ecosystem in the South-West had suffered the same fate, but the Perth Hills area was the worst affected, researchers said. Centre ecologist George Matusick described the collapse, which followed one of the hottest, driest summers on record, as dramatic and quick.

While the problem had been evident in the past few years, he said it became significantly worse in February when healthy trees began turning yellow and died within days. Those dying areas continued to expand until June.

“It’s a very dramatic change, I mean, what happened last summer (to the forest) was unprecedented,” Dr Matusick said.

An abundance of drought-stricken trees has made it easier for fungal diseases such as phytophthora dieback, as well as pests and insects to gain a stronger foothold.

Researchers say record levels of wood-boring insects have invaded the area. “There are up to 110 larvae per square metre where normally you would get just one or less,” Prof Hardy said.

“These are potentially plague proportions, nowhere in the literature can we find those sorts of numbers.”

Meanwhile, wildlife carers say mammals in the area weigh 30 per cent less than this time last year.

Conservation biologist Chris Phillips said the loss of the northern jarrah forest would cause the demise of unique wildlife species that relied on it.

“Black cockatoos are already under immense pressure from habitat loss and with this sudden and rapid decline of the jarrah forest many other vulnerable species of flora and fauna will face an uncertain future,” Mr Phillips said.

Jarrah trees aren’t the only victims, with wandoo, tuart and WA’s peppermint species agonis vital for the survival of the western ringtail possum also in decline.

The Department of Environment and Conservation said it supported the centre’s research and was not surprised by tree deaths in record dry conditions.

It said there was no feasible method of controlling wood borers in natural jarrah forests and more research into tree deaths was needed.

Modelling shows that WA’s South-West will be 40 per cent drier by 2070.

http://www.perthnow.com.au/news/special-features/insect-plague-hits-in-big-dry/story-e6frg19l-1226145214545

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About jboydedu

The Australian Centre for Sustainability Literacy is a division of Julie Boyd and Associates, who have been working for three decades to educate students in becoming positively contributing world citizens. We use a careful integration of solid research and evidence from a broad range of fields across education, community, business and leadership to support the 7th Generation concept which says that all decisions need to be made for the benefit of 7 generations forward.
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