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I've been a Canberran since moving here from Adelaide on the first day of 1980. I now live in suburban Duffy with my partner Louise Maher, ABC 666 radio and on-line journalist. Among my early memories is following Sleepy Lizards (Shinglebacks) around the paddocks north of Adelaide, guarded by the faithful bull terrier. I have always been passionate about the natural world, trying to understand how it works, how the nature of Australia came to be, and sharing those understandings. My especial passions are birds, orchids and mammals. For much of my life I have been a full-time naturalist, running bush tours, writing books etc, doing consultancies, presenting a regular radio slot on local ABC, chairing a government environment advisory committee and running adult education classes. Recently I have eased back somewhat, but am still writing, teaching, doing some radio work and running overseas tours - as part of my fascination with our Gondwanan origins I've been running tours to South America for the past decade. I was awarded the Australian Plants Society Award in 2001 and the Australian Natural History Medallion in 2006, both for services to education and conservation. In January 2018 I was awarded a Medal of the Order of Australia for 'service to conservation and the environment'.

Thursday, 27 April 2017

Litchfield National Park; sandstone and waterfalls

It's often said, perhaps especially in the backpacking tourism industry, both that Litchfield is "a poor person's Kakadu" and "better value than Kakadu" (Kakadu is of course the extraordinary and vast park of floodplains, woodland and sandstone escarpment east of Darwin in the Top End of Australia's Northern Territory.) This refers to the facts that Litchfield is closer to Darwin so can at a pinch be visited as a day trip, and the entrance rates are cheaper, presumably both of which are attractive to travellers having to watch both their time and money (or perhaps just preferring to spend both in other ways). It does share habitat similarities, but it is definitely not just 'mini-Kakadu'. 
Sandstone in tropical woodland, 'Lost City' (of which there are a few in Australia...).

Florence Falls.

Approximate location of Litchfield NP, 100k south-west of Darwin.
The park was declared in 1986, from pastoral leases. Its centre-piece is  a sandstone plateau supporting woodlands which account for the major part of the park's 150,000 hectares (not a small park by any means, though dwarfed by Kakadu's two million hectares). The 'lost city' is a focus of this part of the park, for good reason, though it is only accessible by four-wheel drive.
'Lost City' outcrops.
Sandstone however is prevalent throughout; here's another striking structure.
The woodlands have a grassy understorey, which sometimes extends as areas of pure grassland, which inevitably support a huge termite population.

Magnetic termite mounds, though we now know this is a misnomer.
While these flattened mounds certainly are all oriented north-south, it's not to do with
the earth's magnetic field, but with the sun. The narrow side faces the sun in the hottest part of the day.

Magnetic termite mounds, built by Amitermes meridionalis, from end-on.
These plains tend to be inundated in the wet season, when it's also hottest, so the residents
can't hide from the heat by retreating underground; they must instead manage the temperature above ground.

The equally huge 'cathedral mounds' are built by another species,
Nasutitermes triodiae
(ie 'spinifex termite with nose'!).
On the stony slopes shrubs grow more profusely in the woodland understorey; the restricted-range cycad Cycas calcicola can be a prominent element.
As the name calcicola suggests, this cycad does live on limestone, but only near Katherine;
in the other part of its range, in Litchfield, it is found on sandstone.
There are of course other habitat types present, including monsoon, or vine, forests. These are 'dry rainforests', which grow where there is an intense wet season followed by a very dry season; in Australia true rainforests, with rain all year round, only grow on the east coast. 
Litchfield monsoon forest; palms (especially this Livistona benthami) are prevalent.
This habitat usually grows in strips along stream lines.
I am often surprised at how sharp is the division between the monsoon forest and the adjacent woodlands; I expect nature to be more nuanced than this, but it seems to be the pattern in this part of the world.
Ecotone (transition zone) between Litchfield monsoon forest and woodland.
In some areas, especially at the base of the plateau, low-lying areas support paperbark swamps.
The dominant species in these wetlands is Weeping Paperbark Melaleuca leucodendra.
As the watercourses tumble off the plateau they give rise to the waterfalls which are so popular with visitors, both aesthetically and because of the 'plunge pools' which offer safe swimming at least in the dry season - in the wet crocodiles are known to make their way across country and take up residence. They are removed and relocated somewhere more appropriate (from our point of view at least).

Tjaetaba Falls

Tjaynera Falls.

Tolmer Falls.

Wangi Falls.

Florence Falls plunge pool.
I hope you can agree that this is an impressive and attractive collection of falls! However there is of course plenty of plant and animal life to enjoy too, though the park draws a lot of visitors in the dry, and larger animals sometimes keep their distance from the hubbub. Perhaps a modest parade of some of these species will do to wind up this introduction.

'Screwpalm' Pandanus spiralis; not a palm of course, but a lily relation, and found right across northern Australia.

The beautiful flower of Wild Gardenia G. megasperma.

Wild Gardenia tree; this member of the coffee family (Rubiaceae) is found
across the Top End and into Western Australia.
Gomphrena canescens, family Amaranthaceae, is found throughout the dry north-west of Australia.
Kapok Bush Cochlospermum bixaceae; another widespread tree of the western Top End and Kimberley.
Buchnera linearis, a herb found right across tropical Australia.
Formerly in Scrophulariaceae, now placed in the broomrape family, Orobanchaceae.
Tropical Banksia B. dentata is one of only three entirely tropical banksias, and
the only one to have left Australia - it is also found in New Guinea.

Hibiscus leptocladus, an attractive low-growing shrub.
Osbeckia australiana, family Melastomaceae.
Red-flowered Kurrajong Brachychiton paradoxum; the flowers grow on short stalks from the old leaf axils.
And (almost) lastly a widespread but very beautifully-flowering eucalypt.
Darwin Woollybutt E. miniata often dominates the woodlands.
My last plant offering today is a request for assistance; any idea what this one is?
Thanks in anticipation!
Let's end with some animals...
Yellow-sided Two-lined Dragon Diporiphora magna
Painted Grasshawk Neurothemis stigmatizans.
Dragonflies are abundant in the tropics, but life isn't always easy for them.
Green Emperor Anax gibbosus, a magnificent animal, and probably a magnificent lunch for this spider.
St Andrew's Cross Spider Argiope sp.; possibly the nemesis of the dragonfly above.
It's not just spiders though.
Dragonfly corpse being dismembered by Green Tree Ants.
Green Tree Ants Oecophylla smaragdina are an integral part of the Australian tropics - and elsewhere in south-east
Asia to India, though only in Australia do they have the green abdomen;
this might however just mean more taxonomic work to be done.
For more on these fascinating animals see here.
Two water striders, bugs of the family Gerridae, mating on the water surface.
And my sincere thanks to Craig (below) for pointing out my original embarrassing misidentification!
And there we might leave it, but I hope I've planted the seed of an idea for you. If you're in the area - and winter is coming to southern Australia, so why wouldn't you be?! - please see it for yourself. And remember that you really don't, and shouldn't, have to decide between Kakadu and Litchfield. You need to see both!

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Susan said...

Buchnera is in Orobanchaceae? Seriously?? Pourquoi? (Rhetorical -- I'll look it up for myself...)

I've seen Green Tree Ants dismembering a grasshopper in Kakadu. It's a slick operation.

Ian Fraser said...

I think 'pourquoi pas?' is as rational an answer as any... Though to be fair, the answer will be in DNA.

KayePea said...

A lovely and interesting post thanks Ian, and great photos too.

Anonymous said...

Great post Ian! Very informative. I've visited Litchfield dozens of times (lived in Darwin years ago) and its a special place in my heart. Very jealous!
The photo of the 'Water Spider, Family Pisauridae' is in fact a Water Strider in the bug family Gerridae. The photo is of two mating.
Looking forward to the next post.

Ian Fraser said...

Thank you KayePea for your kind words, I'm glad you enjoyed it.

Craig - thank you for correcting me! How embarrassing... I greatly appreciate your taking the time to share your expertise and help me out. Correction now made.