Jennifer Marohasy

a forum for the discussion of issues concerning the natural environment

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Sea Ice Update

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I have previously blogged about the record low (since satellite measurements began) for Arctic sea ice in 2007, and some of the contributory factors, here, here and here. The record high for sea ice coverage in the Antarctic received little or no media attention.

So what is the current situation? NASA’s earth observatory has an Arctic sea ice update here:

“After record retreat in September 2007, Arctic sea ice had been making a slow winter recovery. Mean sea ice extent remained at record-low levels in October 2007, but beginning in late October, sea ice grew by more than 150,000 square kilometers (about 58,000 square miles) per day for about 10 days—the fastest regrowth observed in the satellite record. Despite this rapid growth, sea ice extent remained below normal for November, though it was not a record low.”

According to the University of Illinois website The Cryosphere Today, sea ice coverage for January 31 2008 is about 900,000 square kilometers below average for the Arctic and about 500,000 square kilometers above average for the Antarctic. Compare past Arctic sea ice coverage from 1980 onwards with the present at the same time of the year here.

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Dead River Red Gums (Part II)

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Yesterday I posted some photographs of healthy Blue Gums in the Grose Valley.

I suggested in the comment thread that followed, that River Red Gums are more suseptible to fire, and that a fire in October 2006 in the Barmah forest destroyed many trees.

River Red Gums are also susceptible to drought.

The following photographs were taken in the Murray Valley last November.

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West of Koondrook before the Kerang turnoff, November 21, 2007

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West of Koondrook before the Kerang turnoff, November 21, 2007

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West of Koondrook before the Kerang turnoff, November 21, 2007

Trees along the Murray River were healthy, but this isolated stand of trees on a farmed section of the floodplain appeared mostly dead – I assume from drought.

Lichen Spiders (Part II)

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In an earlier entry, Lichen Spiders (October 18, 2007), Jennifer described the images of the spiders as intriguing and asked how difficult/expensive it would be to develop the seven images as separate posters/pictures.

I have since accumulated a collection of eight high quality poster size images (30 x 45 cm @ 240 dpi), presented in the thumbnail mosaic below. Interested inquiries should be directed to neil@ccwild.com

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As can be seen within the collection, Lichen Spiders vary in conformity with their background occupancy. However, according to the Queensland Museum Inquiry Centre:

Spider colour is fixed at its previous moult. A slight exception being the abdomen with its much thinner walls which may change especially according to accumulated waste products or what it has eaten. So they can’t change colour like a frog, gecko or squid. Some species of spiders that camouflage on tree bark have multiple colour forms however.

So far as is known, a lichen spider would not be selecting a background according to colour as these are like most (but not all) spiders in having poor vision. It is expected that they would have other ways of detecting a nice lichen-covered background to sit against however.

Under closer scrutiny, the eight images (fully magnified), reveal variation to spider appearance through differential combing of hairs, which appear to have reflective qualities. In the eighth (bottom right) image, much of the blending is also complemented through the shared occupancy of its offspring (see enlargement).

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Blue Gums in Grose Valley Healthy After Back-Burning

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Just over a year ago media reports indicated the Blue Gum Forest of the Grose Valley was “hanging in the balance” because of a wildfire made “more intense, unpredictable and extensive by massive backburning operations”.

I trekked into the forest today and was surprised and pleased to see a beautiful forest with little evidence of fire damage.

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The Blue Gum Forest, Grose Valley, Blue Mountains, Australia, February 3, 2008. Looking to the south-east.

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The Blue Gum Forest, Grose Valley, Blue Mountains, Australia, February 3, 2008. Looking to the north-west.

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The Blue Gum Forest, Grose Valley, Blue Mountains, Australia, February 3, 2008. At junction of Grose River and Govett Creek, looking to the north.

As I struggled up the steep escarpment on my way out of the valley, I passed a couple descending into the valley and I asked if they were planning to visit the Blue Gum Forest.

“Yes,” replied the women, “At least what is left of it”.

Like me, and so many Australians, she believed the media reports that the forest had been badly damaged. As we passed I suggested she would be pleasantly surprised by what she saw.

Why has reporting in the popular press been so negative? Was the state of this iconic forest misrepresented as part of a wider campaign against back-burning?

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Additional Notes and Links

Link to picture of burnt forest in Sydney Morning Herald:
http://www.smh.com.au/news/national/the-ghosts-of-an-enchanted-forest-demand-answers/2006/12/10/1165685553891.html

Link to earlier blog post with a question from Bill in Melbourne about the state of the forest:
https://jennifermarohasy.com.dev.internet-thinking.com.au/blog/archives/002620.html

The Blue Gums in the Grose Valley are Mountain Blue Gums Eucalyptus deanii, here are some links to the more common Tasmanian Blue Gum, Eucalptus globulus:
http://www.abc.net.au/landline/content/2006/s1702968.htm
http://www.ibiblio.org/pfaf/cgi-bin/arr_html?Eucalyptus+globulus
http://en.wikipedia.org/wiki/Eucalyptus_globulus

The Giant White-tailed Rat

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One of Australia’s largest native rodents, the Giant White-tailed Rat (Uromys caudimaculatus) has such formidable teeth and jaw strength, they have been known to eat through steel garbage bins. They are also capable of dispersing large-seeded tree species in Australian tropical rain forests, including some that have no alternate vector, such as the magnificent Yellow Walnut (Beilschmiedia bancrofti) (Lauraceae).

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When I first settled into the Daintree rainforest, I was surprised by the local council’s provision of free rodenticide for “vermin control”. Never mind that these were protected species and inhabitants of World Heritage estate, apparently they were rats first and foremost and therefore vermin.

There is quite a diversity of native rodent fauna in the Daintree rainforest, but as far as I know, no introduced species. The Bush Rat (Rattus fuscipes coracius) looks most like the notorious Black Rat (Rattus rattus) of bubonic infamy, but even these are protected by legislation.

Over the years, newcomers settling into the rainforest have expressed dismay at the intrusion of rodents with not the slightest regard for the meticulously installed barriers of fly-wire mesh. Aggrieved home-owners almost invariably resort to trapping the trespassers, as sensitively as possible, and transporting them to a remote corner of the Daintree for release. Like-minded counterparts could very possibly be doing the same thing, from the opposite direction and it would be interesting to know how this shuttling of rats around the rainforest affected their social dynamics, for it most certainly does not affect the continued breaching of residential boundaries. Residents either accepted the inevitable or leave.