Expeditions

TO ALICE AND BACK

In August 2016 I travelled to Alice Springs to collect Themeda (a grass), Calandrinia and other prospective CAM succulents (e.g. Anacampseros, Bulbine, Gunniopsis, Portulaca, Zygophyllum), to visit The Mac Clarke Acacia peuce reserve, and just to see the Central Desert after rainfall when flowers are blooming, .

My host in Alice was the indomitable Peter Jobson. Senior Botanist at the Northern Territory Herbarium at Alice Springs and a JCU botanical alumnus. Unlike me, Peter is a real botanist.

Jobbo not only put up with me but put me up! He kindly took me on plant hunting trips to Standley Chasm, Owen Springs, The Mac Clarke Acacia Peuce Reserve, Lambert’s Corner, Chamber’s Pillar and other places.

Despite all my years of studying desert plants, this was my first trip to Central Australia! I saw plants in situ rather than growing in pots in a glasshouse. We did a lot of kilometers and took quite a few photos (I seem to have misplaced a few). Below, I divide the tour into topics and show relevant photos. The first slide-show is a bit of a hodge-podge…

From Townsville to Alice: I drove via the Flinders Highway to Hughenden, the Kennedy Development Road through Winton and Boulia, the Donaghue Highway and across the Plenty Highway (overnighting at Winton and Boulia).

From Alice to Townsville: I was chased by rain on the return trip. Rather than chance a wet muddy Plenty Highway, I drove north along the Stuart Highway to Three Ways and drove to Townsville via Camooweal, Mt. Isa, Boulia and Hughenden, sleeping at Tablelands, Boulia and Hughenden.

Chamber’s Pillar: The tops of these pillars we see now were probably the lowest points of the landscape during the Cretaceous!

By the Cretaceous, ca 80 mya, much of Central Australia was an inland sea (Eromanga Sea) that extended through the Gulf of Carpentaria. Sands, silts and clays eroded from old Carboniferous landscapes were deposited from the sea and rivers that fed into it.

The Cretaceous climate in Central Australia was seasonally wet and dry. When it was wet, iron in the underlying rocks dissolved in groundwater that percolated upwards during the dry seasons. The water evaporated and the precipitated iron bound with the surface material to form a tough difficult-to-erode surface layer, ferricrete. The sedimentary layer below is relatively soft.

Around 20 mya, during the Miocene, when Australia’s climate dried a bit, rates of erosion increased appreciably, particularly of the softer parts of the landscape. As a consequence, much of the current land surface in Central Australia is 100 m or more below the ancient plain!! Where the ferricrete layer reduced the rate of erosion of the underlying sediments structures such as Chambers Pillar and many mesas have formed. Their demise is only a matter of time…

The Mac Clarke Acacia Peuce Conservation Reserve: Peter and I travelled the 300 km to Mac Clarke via Santa Teresa and thence the Old Andado track, in order to see the smallest of the three known populations of Acacia peuce (waddy tree). Listed as vulnerable under Australia’s Environment Protection and Biodiversity Conservation Act, A. peuce which can attain 15 – 18 m, is Australia’s tallest desert tree. It’s wood, a beautiful intense brown, is the second most dense of any Australian tree (1,100 – 1,300 kg m^-3).

The three known populations of A. peuce lie on the outskirts of the Simpson Desert. The two eastern populations are near Mt. Lewis, Birdsville, and Coorabulka Road, Boulia. At Mac Clarke, the only population on the western side of the Simpson is surrounded by the desert and is a mere 1,000 plants. The mature trees are subject to fire, lightning strikes and a drying climate. The reserve protects seedlings from grazing by cattle and rabbits.

An extensive source of information about A. peuce can be found in Jon Luly’s document entitled A compendium of current wisdom regarding the waddi tree.

We left Mac Clarke chased by rain. The infra-red light reflected from the clouds accentuated the colours of the desert reds, oranges and greens.

Lambert Centre of Australia: We camped here, the geographic centre of Australia. More importantly for us, the spot was a paradise of flowers, especially Calandrinia. Loved the ‘flick-dry’and ‘drip-dry’ signs on the toilet block! (I believe the block is now destroyed).

Trephina Gorge NP: is nestled in the east MacDonnells ca. 85 kilometres east of Alice Springs. The hills around the gorge are bisected with steep-walled erosion gulleys and the soil surface is covered in small angular stones (quarzite?). A lovely spot. The John Hayes waterhole is a welcome oasis.