When sheoaks take over

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I recently had an opportunity to go for a few hours’ wander on the Queen’s Domain in Hobart, a huge park covering a hill near the city, which still contains some great native vegetation. Having often walked and played there as a kid in the 1980s I have a little historical perspective on the place, and the recent domination of former grassy woodlands by thick stands of drooping sheoak (Allocasuarina verticillata, previously known as Casuarina stricta) saplings really stood out.

I recall a family outing on the Queens Birthday firecracker night, for which we walked up onto the western side (above the Brooker Highway) and let off our fireworks while enjoying the view across the suburbs where everyone else was doing likewise. We spent the evening sitting in the grass in an open woodland environment with some trees and shrubs around. It was easy to walk through. Some areas on the north side still look a bit like the west side did in the mid 1980s. Continue reading

‘Australian Grasses (With Illustrations)’ by Fred Turner

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The old man told me that as a young botanist circa 1970 he surveyed the pasture grasses of the NSW western slopes. Apparently he was particularly interested in the native grasses, but his superiors weren’t so impressed by this focus (he says) and he didn’t continue in that job.

Australian pasture grasses are still underappreciated and poorly understood. Many graziers prefer introduced grasses, including disastrous weeds like Buffel grass.

Recently, Dad got me a secondhand copy of Fred Turner‘s 1895 book Australian Grasses (with illustrations). A few people are beginning to appreciate Australia’s native grass landscapes for not only their ecology but in some cases as drought-hardy plants for grazing livestock. Turner noted this exact potential in many native grasses, and promoting them was a major part of his book. It’s amazing (if a little depressing) how many of the themes he introduced 120 years ago are still current. Continue reading

The epic geologic saga of Bacchus Marsh

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How did the landscape at Bacchus Marsh form? It’s an area rich in geological history, believe it or not. The Werribee Gorge in particular exposes a lot of this history in the rocks it has cut through. This short history is based on material gathered in a couple of geology subjects I took. A bit of geological jargon is introduced in italics, with some explanation for the more obscure terms. Look it up on Wikipedia if you need more explanation!

It all started in a primeval sea

How far back do you go to tell a story? If we want to introduce the characters and setting, perhaps the Ordovician period of the Paleozoic era is a good time for this story. This period started 485 million years ago (485 ma in geological shorthand) and lasted for 41 million years (that is, until 444 ma).

You should be aware that since the discovery of plate tectonics last century, we know that the lumps of rock that make up continents are pushed around the globe over many millions of years, floating on the slowly churning, semi-fluid magma beneath the Earth’s crust. Well, in the Ordovician, the main part (that is, the craton) of the Australian continent was part of the Gondwana supercontinent, and the Australian plate was then located about at the equator.

At this time, most of what’s now the eastern states of Australia wasn’t there. Primeval mountain ranges, around where today’s Flinders and Barrier ranges are, were eroding a steady stream of sediments into the ocean off the coast. These sediments created large deposits – turbidites – off the continental shelf. Continue reading

Indigenous plants for a degraded site

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Our local Friends group asked me to work out plant lists for autumn/winter plantings along the river. How to work out a plant list? With all the changes wrought since colonization, and further coming with climate change, what species are appropriate?

Once all of the plain at Bacchus marsh was some kind of redgum swamp, with billabongs, and rivers and streams frequently changing course across the floodplain. There’s still a billabong down at the Parwan end, near where the Werribee and Lerderderg rivers meet, but it’s on private land so most won’t have seen it.

In the section we planted on April 3, near the main Grant St bridge over the Werribee River, the river has been artificially deepened to prevent flooding. As the story goes, the farmers held title to the middle of the river, but the river kept moving so this caused some friction between landowners. At some point, they banded together and dug a deeper, permanent channel. Continue reading

One that didn’t make it

Honeyeater chick trapped in plastic nest materials

Previously I posted about the drama of the white-plumed honeyeater caught in a tree due to a synthetic thread that had caught around its claw. One hypothesis a birder friend put to me was that it was a young bird who had caught its claw on the thread whilst in the nest.

A dessicated cadaver under the trees across the road from my place bears out this theory. This one never made it out of the nest, although perhaps it managed to drag the nest with it a little ways. Continue reading

A dry year.

Only the toughest survive: saltbush Atriplex semibaccata, and the ubiquitous carpetweed, Galenia pubescens

While the El Nino weather system is apparently breaking up, perhaps facilitating more rain, it’s been an incredibly dry year.

How dry? February rainfall has been about 4mm. When you get a millimetre or two in summer, it evaporates as fast as it falls, so it may as well have been nothing.

Dry and dusty. Time to get out the banjo and play the blues. Continue reading