Red Gums: good news vs bad news

So, what’s going on with our River Red Gums?

We noted last year how lots of them were looking pretty dire, and this year is, if anything, worse: whole roadsides and paddocks in this region and beyond are looking pretty desolate where the Red Gum is the dominant tree.

Damaged Red Gums east of Mount Alexander, November 2017: Psyllid attack is devastating the foliage.

The main culprit, it seems, is the Psyllid lerp, a leaf munching creature whose larvae suck out the nutrients from the tree leaf. The result is often the eventual death of the leaf, and the presently common spectacle of trees with sparse or dead looking foliage.

The good news is that these infestations come and go, and in the natural order of things, the trees come back. If you look closely at some of the apparently terminal trees around the place, you can see fresh leaf growth coming on. And we’ve had the experience of the Stringybark forests in the south of our region a few years ago being absolutely stripped by colourful but gluttonous cup moth larvae. They recovered.

Fightback: new growth emerges on damaged Red Gum, Campbells Creek, November 2017.

The potentially bad news is that distortions in natural conditions may make the trees less resistant to such attacks. Extended drought conditions, for example, may not only weaken trees, but cause bird populations to decline.

This latter is important because birds—specifically pardalotes—are among the most effective predators of Psyllid lerps.

The moral of the story is: maintain forest and woodland resilience by protecting diverse understorey habitat for important birds and insects, and creating vegetation corridors to link vulnerable tree populations.

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