Jennifer Marohasy

a forum for the discussion of issues concerning the natural environment

jennifer

Gilbert’s Potoroo to Survive Syphilis?

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I’ve never seen a Potoroo – apparently members of the genus look like rats and can hop like kangaroos.

The Gilbert’s Potoroo is Australia’s most endangered marsupial and it’s not climate change but rather syphilis that may result in its extinction. At least that’s what an ABC Online article suggests, but when you read a bit further there is reason for optimism because there is a syphilis-free population on Bald Island.

Read more here: http://www.abc.net.au/science/news/stories/2007/2089599.htm

Thanks to both Libby and Woody for the link.

And here’s a link to the Gilbert’s Potoroo’s Action Group website: http://www.potoroo.org/

Murray River Tributary Reduced to Billabongs

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While the Murray River is flowing strongly despite the drought, many of its tributaries are drying up.

Yesterday I visited the Wakool River with Wakool Landholders Association Chairman John Lolicato.

He showed me a spot downstream of Gee Gee bridge where there is still water in deep holes. A bit upstream the river has been reduced to billabongs and further upstream in Possum forest some of the billabongs have dried up.

John Upstream Gee Gee Bridge (copy Wakool River 026).jpg
Downstream of Gee Gee bridge

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A billabong that was Wakool river

John has moved some Murray Cod from drying billabongs to larger water holes.

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John looking for some water and stranded fish

Also yesterday, the NSW Minister for Climate Change, Environment and Water Phil Koperberg announced that a pulse of water would be released into the Wakool River to provide stock and domestic water and environmental benefits.

Mr Koperberg acknowledged that the Wakool River had not had flows for months due to the severe and extended drought.

“The diversion of water into these systems will provide landholders with access to stock and domestic water for the first time in months, help improve water quality and provide significant environmental benefits to stressed populations of native fish and other aquatic species,” he said.

“The water cannot be used for irrigation and additional deliveries for irrigation are not viable as they would exacerbate additional water losses that cannot be supported.”

After the ‘Top Island’ Fire in the Barmah Red Gum Forest

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Aborigines managed much of the Australian landscape with fire. This management strategy favoured fire tolerant and fire resistant species – perhaps why gum trees dominate so much of the Australian landscape. But river red gums, Eucalyptus camaldulensis ssp., unlike most gum trees, are not particularly fire tolerant.

Barmah Speedboat (copy of Redgum 069).jpg
A boat on the Murray River in the Barmah Forest. Photograph taken last Tuesday.*

The timber cutters and cattlemen who live and work along the middle Murray (river) have gone to great lengths to keep fuel-loads in red gum forests low through controlled grazing and the collection of firewood. This, combined with a network of rural fire fighting brigades, has made it possible to stomp out fires started from lightening strikes or camp fires.

This may explain why some foresters and aboriginal elders call river red gums ‘white fellas’ weed’ and why areas which were once open woodland are now covered in dense red gum forests including at Barmah.

Barmah Duck Hole Plain (copy Redgum 043).jpg
This area in Barmah Forest was once known as Duck Hole Plains

But the situation is changing. The Victorian Environmental Assessment Council (VEAC) wants more wood and grass on the forest floor apparently to increase biodiversity. This means higher fuel loads and according to some white fellas** the forests will ultimately be severely degraded by uncontrolled and uncontrollable feral fires.

A wildfire in the Barmah Forest, in an area known as Top Island, burnt out 800 hectares last October.

Barmah Fire blog (Copy Redgum 026).jpg
Burnt forest at Top Island in October 2006, photograph taken Tuesday November 6, 2007.

Old habitat trees are apparently the first to go when a hot wildfire burns through red gum forest. Last week the Barmah woodcutters showed me how the old trees ‘burnt like chimneys’ from the inside – out.

Parts of ‘Top Island’ look like they are regenerating. But I’m told that the green coppice growth will eventually fall off – that these fire-damaged trees will never develop as habitat trees. Habitat trees have hollows for wildlife.

Barmah Fire Regrowth blog (Copy Redgum 028).jpg
Coppice and a burnt-out old habitat tree.

Where the forest has been completely burnt, for example after the sand-spit fire of the late 1960s, and where there has been no management, the red gum regrowth can be very dense.

Barmah Sandspit fire growth (copy Redgum 072).jpg
Regrowth from the 1968 Sand-spit fire, Photograph taken November 6, 2007.

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* All the photographs in this blog post were taken in Barmah forest last Tuesday – on Melbourne cup day.
** I use the term ‘white fellas’ to refer to the guardians of traditional European knowledge in the Barmah forest.

Glacier Dynamics and Why Greenland Not in Danger of Collapse

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Dear Jennifer,

Professor Ollier takes on James Hansen’s claim that the Greenland and Antarctic ice sheets are in danger of collapse due to global warming. Hansen’s claims are the basis for Al Gore’s suggestion, in An Inconventient Truth, that the seas may rise by 20 feet in the near future.

Professor Ollier argues that, “Hansen’s seeming ignorance of the mechanism by which glaciers flow leads him into major errors.”

You may have seen Professor Cliff Ollier’s write up of glacier dynamics originally circulated by Benny Peiser’s excellent CCNet newsletter. The Center for Science & Public Policy has published a paper adapted from the original article with expanatory footnotes and diagram added to clarify some of the more technical parts of the article.

This paper describes glacier dynamics, such as the glacier budget, how glaciers flow (through a process known as “creep”), how creep is related to temperature and stress, and how the simple rules of creep allow us to understnad some observations of glaciers.

We hope you find this paper useful.

http://ff.org/index.php?option=com_content&task=view&id=396&Itemid=77

Paul Georgia
Center for Science & Public Policy
Frontiers of Freedom

Thinning Red Gum Forests at Koondrook

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I’ve been staying with friends who live on the Murray River in western New South Wales and I’ve seen a lot of river red gums – beautiful old habitat trees, thickets of young saplings, healthy forests, water-stressed forests, bushfire- damaged forests, trees ready to be made into railway sleepers, others into veneer.

Many of the forests are suffering from the drought. While some activists claim the solution is more environmental flow water allocation, this is unlikely until the drought breaks. In the meantime some believe some forests can be ‘drought proofed’ through thinning.

In the following picture the density of red gums has been reduced through a thinning operation on private land. On the other side of the fenceline the trees have not been thinned.

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Koondrook Forest, 3rd November 2007

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Habitat tree clearly marked for saving.

A recent Victorian Environmental Advisory Council (VEAC) report proposes that more red gum forest along the Murray River be converted to national park – this time about 100,000 hectares.

The report states that many forests are severely stressed and that there is evidence that without improved environmental flows many of these forests may be lost over time.

But locking them up as national parks may only exacerbate the situation. Indeed what many forests appear to need now is thinning, to reduce competition for water between trees.

Some of the forests along the Murray River in the best condition right now are the more actively managed forests – with lower tree densities from thinning as well as forests that received environmental flow allocations in the last few years.

Still Water in the Murray River

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Last week I drove from Brisbane (south eastern Queensland) to Barham on the Murray River.

Listening to the news in Brisbane I was getting the impression the Murray River was nearly empty of water.

In fact there is still a lot of water in the river but the Hume and Dartmouth dams are very low. Also, some of the tributories of the river are being shut-off with cod dying in the ‘shrinking’ billabongs. And many river red gums on the flood plains are looking very stressed from the drought.

Barham_boat n text Nov3_07.jpg

But as this picture shows, the river itself is still magnificent and the red gums along the river beautiful.