This project illustrates a scientific research expedition to the drylands of central Australia. The objective of the research was to better understand dryland soils which are under threat from climate change and land use. Understanding soils can help us figure out better ways of protecting and managing the environment.
We drove two days from Brisbane to reach the field site in Diamantina National Park.
Sunset in “Big Sky Country” - a vast flat expanse.
The next day we went out to survey the area, especially the huge flat claypans we had specifically come to see.
The claypans were covered in a crust derived from the interaction of biological and physical phenomena.
Without the biocrust there, this soil would be highly vulnerable to wind erosion, contributing more as a dust source in this area which is prone to dust storms.
Looking closer it can be seen that the wind is cutting away the soil around quite tough cyanobacterial crusts. Also on top of the biocrusts is a brown “varnish”, which is probably of physical origin, not biological.
This gate was found on Lake Constance claypan. Can you solve the riddle?
Lake Constance claypan is a really huge expanse, almost perfectly flat, and seemingly featureless on first impressions.
On sand dunes surrounding the claypans, there are biocrusts too but they are different.
Biocrust is where biology meets geology, for the threads gluing together sand grains are made by and from microorganisms in the soil.
This video shows a lifted biocrust close up. A light breeze makes it easy to see how tiny threads hold the sand together.
Often biocrust gets buried, and when this happens another crust can form on top. When digging deep holes on sand dunes we noticed evidence of this having occurred many times over the years.
Diamantina National Park is a semi-arid zone near to the Simpson Desert. Compared to the Kalahari in Botswana which is climatically similar, there is much less obvious life other than plants. However, during 3 weeks fieldwork I noticed the abundant hidden life.
These ants were excavating a biocrust.
By sequencing DNA extracted from biocrusts, we find out which types of bacteria live here. We are still working out which bacteria perform particular functions in the soil.
And here is a biocrust that I excavated. The strength of the crust comes partly from the microorganisms which glue the sand grains together.
This solitary wagtail visited us every day in the field. It was tame and would take food from the hand.
Many spiders like this were around. They live in holes in the ground, which they cover over with a lid. This spider is in process of struggling to drag an ant down it’s hole.
The Gidgee tree achieves a remarkable feat of survival in this hostile land.
Fallen trees make a habitat for other life.
The Diamantina river floods occasionally due to rain falling far away in the north.
Most of the time the Diamantina isn't in flow but remains as disconnected pools like this. In the dry central region of Australia such pools are important water sources.
Back at the ranch this old diesel engine sits at the foot of an even older broken wind turbine. The wind power, then diesel power used for electricity generation are now usurped by solar. Diesel is retained for backup.
Sleeping under the stars was worth the chill.
And even worth being woken by a road train.
Fieldwork involves long days and sometimes difficult hours. We measure the world on it's own schedule.
Dawn at the disused cattle ranch which we used as our research base.
This research project was funded by the Natural Environment Research Council (NERC), UK.
