Dismantling feral ecosystems

Basalt escarpent, overrun with serrated tussock

I’ve been privileged to work for a few weeks on a basalt escarpment in Melbourne’s western suburbs. The area is spectacular; I love the views and geology and flora of the escarpments. Even this one, which is seriously infested with invasive exotic species.

The section I’m working on is overrun with serrated tussock (Nasella trichotoma), a South American native that causes big problems in agriculture and native grasslands. It’s an attractive species, but tends to smother everything around it – and its seeding panicles (seedheads) break off and blow in the wind, spreading it far and wide. Native animals, stock, and even rabbits barely touch it, preferring to eat almost anything else including all the native species. So it has a great competitive advantage, and easily takes over (especially under heavy grazing). It sets thousands of seed per plant, building up a huge reservoir in the soil seed bank. Continue reading

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Mistletoe on the Christmas Bush

Christmas, a northern hemisphere religious/cultural festival associated with the winter solstice and (obviously) Christian and earlier pagan religion, can seem a bit odd translated into the Australian summer.

“Ecology is Not a Dirty Word” has blogged on a few of the Australian christmas-theme-compliant plants and flowers and their ecology. Have a read of that; and here’s my add-on.

Depending on where you are, “Christmas Bush” may refer to a number of different plants. Around here it would be the shrub Bursaria spinosa, but the name “prickly Bursaria” is more common. Continue reading

Living on the edge

Moonah at Parwan Gorge

Where the volcanic plains were cut through by the river, just east of Bacchus Marsh at Parwan Gorge, giant blocks of weathered basalt tumble over the edge of a precipitous, wind-blasted escarpment.

A harsh environment, on the edge of the fertile plains, above the fertile river valley, but vastly different from either. In this peculiar niche a special community lives: the escarpment shrubland. Crowning it all is a row of ancient Moonah trees (Melaleuca lanceolata). Continue reading

Disjunct Distribution: the Bacchus Marsh White Cypress-pines 30 years on

What’s an inland, arid region tree doing hundreds of kilometres south of its native range? How did it end up here?

Callitris glaucophylla
White Cypress-pine stand near Bacchus Marsh

Along the Rowsley escarpment and nearby at Melton*, there are a couple of isolated populations of ancient White Cypress-pine, Callitris glaucophylla. The next nearest (isolated) report of this arid-zone, inland species is from over 100km north, at the Whipstick state park just north of Bendigo (according to the Atlas of Living Australia). Continue reading