Bringing back the dead with old ecology photos

Mallee Swale Eucalypts Wyperfeld 1982 Cheal

Take a close look at the coppicing trees in the old photo above. Notice anything unusual?

Perhaps it looks like any other stand of burnt mallee? Perhaps it does. But most of the trees aren’t resprouting after a fire. They aren’t recovering from drought, insect attack or damage by humans either. What could have caused the damage? The photo below of dead foliage on Mallee Tea-trees (or Green Tea-trees), Leptospermum coriaceum, provides a clue.

Leptospermum coriaceum Wyperfeld 1982 Cheal

In winter 1982, Wyperfeld National Park experienced the worst frost on record. I described the event in an earlier blog. Shortly after the frost, researcher Terry O’Brien wrote:

The impact on the vegetation was dramatic. Thousands of hectares of mallee scrub and heathland were devastated, especially in the interdune swales.

When I wrote the story, I knew of only two photos of the frost-killed trees, in an out-of-print book: ‘Mediterranean Landscapes in Australia, Mallee Ecosystems and Their Management’. According to some of my students, information that isn’t on the web doesn’t exist. Only digital information is accessible. So it’s time to bring imagery of that frosted landscape back from the dead.

Ancient photos unearthed

In 1982, David Cheal worked as a plant ecologist at the National Parks Service of Victoria. He knew Wyperfeld National Park well and took many photos after the big frosts. These are his photos, scanned from old slides and photoshopped a trifle to remove the dust and blemishes. As far as I know, David’s photos are the only publically available, digital images of ‘the cold that killed the mallee’.

Leptospermum coriaceum Tea-tree Heath Wyperfeld 1982 Cheal

The tall green trees in the photo above are Cypress-pines, Callitris gracilis and C. verrucosa. Cypress-pines are tough as floorboards. The frosts didn’t harm them. Eucalypts were more sensitive. The coppicing eucalypts in the top photo grew in a swale where the frost was most severe. They responded as they would after a fire, resprouting from the lignotuber at the base of the trunk.

You may be wondering why the ground layer in the top photo is so open and devoid of leaf litter. The site was hit by a double whammy of disturbances: first by fire and then, a year and a half later, by frost.

Mallee Swale Eucalypts Wyperfeld 1982 Cheal

After the fire, the trees resprouted from the base and Wheel-fruit plants (Gyrostemon australasicus) regenerated from seed. The frost killed the tops of the Wheel-fruit – they’re the wispy herbs in the foreground – and killed most of the resprouting foliage on the eucalypts. You can see the frost-killed leaves at the base of the trees on the right of the photo. The trees then resprouted once again, creating a second green flush of coppice regrowth. You just can’t keep a good mallee down.

Mallee Tea-trees followed the eucalypts’ example. Across thousands of hectares, the aerial shoots were killed and the shrubs resprouted from the base. Slowly they grew to dominate the mallee heathlands once again. A photo David took in 1993 shows recovering tea-trees 10 years after the frost. The frost-killed branches still stand above the new flowering shoots.

Leptospermum coriaceum frost regrowth 1992 Cheal

Not all plants are as hardy as mallee cypress-pines, eucalypts and tea-trees. As described in the earlier story, the biggest loser was Desert Banksia, Banksia ornata. In 1986, Terry O’Brien and colleagues wrote:

With the exception of sporadic survivors, all adult [Banksia] ornata in frost-affected swales were eliminated.

Now we can see those swales of dead Banksias, thanks to David Cheal’s old slides. The scenes below extended across thousands of hectares. The large-leaved shrubs are Desert Banksias, the fine-leaved shrubs Mallee Tea-trees, and the tall green trees are cypress-pines and eucalypts.

Banksia ornata heathland Wyperfeld 1982 Cheal

Unlike the eucalypts and tea-trees, Desert Banksias didn’t resprout and few seedlings emerged. Across vast areas of the mallee, the banksias disappeared.

In many parts of the Park, the only surviving adult [Banksia] specimens are now located on dune crests and upper dune slopes above the level affected by the frosts.(O’Brien et al. 1986)

In David Cheal’s words: “The frosts were … one of those rare stochastic ‘natural’ events that have impacts for centuries. We talk about these events in ecology and hypothesize about their long-term impacts but we then usually forget about them and interpret landscape patterns in terms of the current climate and other conditions … We should never forget the long-term impacts of major perturbations on landscape patterns. Extreme events matter, and may matter for a very long time afterwards.”

Frost killed Banksia ornata Wyperfeld 1982 Cheal

We humans are visual creatures. Imagine reading about pandas without ever seeing a photo of one. Would you be convinced of their alleged cuteness? I doubt it. ‘Nah’, one might reply, ‘I’m sure my kids are way cuter than those hairy things’.

Imagine reading about a huge ecological event of which all traces had long disappeared. Would you consider it critical, pivotal, or merely interesting? Imagine trying to convince future readers of the impacts of climate change, without photos to demonstrate changes. A futile endeavour?

Photos of ecological changes are incredibly important. They generate our interest, trigger our emotions and spur our engagement. If a Banksia died in the mallee and nobody snapped … would anybody care?


Acknowledgements

I am indebted to David Cheal for kindly allowing me to share his valuable photographs of the frosted mallee, and for proof-checking this post.

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11 thoughts

  1. Hi Ian – cool piece. I wonder if greater climatic extremes associated with climate change could increase the frequency of very rare events like this? …or will the general warming make such an event less likely? Or is hypothesising about these things a fools game?

    1. Hello Nick, thanks for writing in. Great question but I’m afraid that any answer would be pure speculation. I discussed climate change briefly in the earlier blog on frost in the mallee – at https://ianluntecology.com/2014/08/31/frost/ . Paradoxically, there is good evidence that frosts are becoming more frequent in the mallee, despite increases in average temperatures. However the impact of climate change on extremely low temperatures, as occurred in 1982, is unknown. Thanks again, best wishes Ian

      1. 1982 was an extreme drought year – I think the driest winter in the past 40, and probably longer. Such years with very low humidity and very clear skies are often associated with very severe frosts. Will these be more frequent in a changed climate? Probably.

  2. Hi Ian. Dave Ashton’s huge collection of carefuly labelled slides would be a very valuable archive. Do you know where they are?

  3. Hi Ian, my grandfather was keen on filming the mallee, unfortunately he was not so good at it and only a couple of films remain. The most famous one in our family is the waterskiing on the wheat crops (testament to his filming ability). On a more serious not another record exists which you might not know of. While looking at survey maps in the lands office I found a microfiche of Daytrap which is where my great grandparents farm was/is. On this, the contours were lines of text, describing the vegetation. I dont know how many more are done in this way.

    1. Hi Colleen, thanks for writing in. There is a tiny Daytrap Bushland Reserve in the mallee still, but not much other native vegetation surrounding it nowadays. I assume your great grandparents’ farm must have been near it?

      Lots of early maps of Australia contained fantastic information on original vegetation patterns. Years ago I used many of the microfiche maps to work out where woodlands and grasslands were in Gippsland and on the Bellarine Peninsula. Many of the maps have now been scanned and are on the web, which makes the task a lot easier than it was in the old microfiche days. There is a good description of how to access the scanned maps at the Public Records Office web site – http://prov.vic.gov.au/provguide-30. I’m sure the Victorian archives center would love to see a copy of your great grandparents waterskiing too! Thanks again and best wishes, Ian

      1. Would you believe my maiden name is Grant, which is the track that runs though it. I don’t think I ever visited it although my father was known to collect plants from the roadside and send them off for identification. There is a huge collection of family pics so I will check with family. Cheers Again. Colleen Miller

  4. Thanks Ian – cool piece that makes us think (once again) about ecological change and its drivers. And how we forget so easily our past. I’m in touch with Terry O’Brien (indeed we are working on a paper on semi-arid annuals!) – I’ll ask if he has old photos stashed away. He had a couple of Honours students working on the ecophysiology of re-sprouting up at Wyperfeld, including Lisa Jobe – so there is probably a wealth of info hidden away in unpublished theses.

    I guess your post also reminds us that seeking out the past helps inform our future. Just recently returned from a field trip up at Mushroom Rocks at Baw Baw NP. There is an ancient Acacia dealbata (Silver Wattle) stand at the rocks with no eucs in sight. A quick check of TROVE and I found that 80 yrs ago there were dead stags of (probably) Alpine Ash visible around the rocks. I suspect two fires have knocked off the Ash (perhaps 1926 and 1939) and allowed a monospecific stand of Silver Wattle to develop. They are now senescing, so who knows where the veg is heading. But I can be sure it’s not cycling back to Ash. Best wishes, JOHN

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