Pilbara mine sites a tough challenge

Dr David Merritt (Research Scientist), Dr Todd Erickson (Research Scientist)

The Pilbara is one of the most spectacular bioregions of Western Australia. The expansive grasslands dotted with imposing mesas are intersected by the rivers and flood plains of the Fortescue Marsh. These visions typify the Australian outback with endless blue skies contrasting the red, rocky soils.

This ancient landscape is floristically diverse for a semiarid region, supporting around 1800 native plant species. The region is also a bonanza for the Australian economy as one of the world’s primary sources of iron ore and other minerals.

Drylands such as the Pilbara are important regions of the world, covering almost half the Earth’s land surface. Photo: Alexandra Rouillard

One of the consequences of mining is thousands of square kilometres of disturbance and degradation.

Kings Park Science has a long history of research in this region to support ecological restoration, forming longrunning partnerships with industry including BHP and Rio Tinto. A primary focus has been the development of seed technologies to improve our capability to re-establish biodiverse plant communities on the large scale necessary to repair mining footprints.

A starting point is seed biology, particularly the requirements for sourcing large amounts of seeds, storing seeds and developing the know-how to germinate them.

One highlight of this research was the release of the Pilbara Seed Atlas and Field Guide in April 2016. This photographic guide to more than 100 species synthesises over a decade of research into their seed biology and propagation for restoration.

Knowing how to store and germinate the seeds is just the start. We must understand how seeds behave in the natural environment to successfully restore vegetation and use this insight to increase the chances of seedling establishment.

Over the past seven years a major program of field trials has been conducted as part of a research partnership with BHP. In 2014, under the Restoration Seed Bank Initiative, a Controlled Environment Facility (CEF) was built at BHP’s Mt Whaleback mine site. This facility houses 32 experimental plots that hold various types of reconstructed soils typically encountered following mining operations.

The Controlled Environment Facility (CEF) at Mt Whaleback. This 1600m 2 rain out shelter has proved to be vital to testing seed technologies. Photo: David Merritt

The CEF is the site of long-term studies on soil amendments and plant health. Photo: Todd Erickson

Different rainfall scenarios can be simulated through irrigation of the plots, providing the ability to field-proof seed treatments developed in the laboratory and a stepping-stone to full-scale field trials on mine waste dumps.

Seeds are the starting point to reintroduce vegetation, but they need to be placed into soils that can support plant growth. Mining significantly alters the topography of the landscape and removes the plants, animals and topsoil during the resource extraction process.

The waste materials are typically formed into vast novel landforms that become the new substrates for restored vegetation, yet are foreign to the local seeds and plants.

Soil science has been a major component of recent research in the Pilbara, particularly examining the use of organic or inorganic amendments to improve soil conditions.

Seed pelleting techniques are being developed to incorporate naturally occurring soil microbes as a means of re-introducing these to the restoration sites. Long-term trials in raised beds on the perimeter of the CEF continue to track soil microbial activity, fertility and other measures of the recovery of the health of reconstructed soils as plants establish and grow.

Another major component is to improve mechanised seed delivery. We have designed, constructed and tested new seed processing techniques through collaboration with mechanical engineers at the University of WA and research partnerships with BHP, Rio Tinto and others. New equipment includes seed flaming and novel direct seeding machinery suited to sowing native seeds in the sloped and rocky landforms common to the Pilbara mine sites.

A US Patent was granted in 2021 for the Kings Park and University of Western Australia seed flaming invention. Units have been built for research and commercial development. Photo: The University of Western Australia

One thing we’ve learnt on this journey is that complex biological problems associated with restoration cannot be solved by individual scientific disciplines or institutions.

Solutions require partnerships with like-minded organisations, scientific collaboration and a long-term vision and commitment.

Collaboration with scientists from the US, South Africa and Mediterranean regions who face similar challenges in large-scale restoration of dryland ecosystems has been invaluable. The research has supported more than 30 postgraduate student projects over the past 10 years. Photo: Todd Erickson