Public Talk: Plant diversity in south-western Australia

Dirt-poor soils, pesky parasites and friendly fungi shape plant diversity in south-western Australia

The 2022 George Seddon Memorial Lecture by Professor Hans Lambers FAA FRNAS, UWA School of Biological Sciences

Southwest Australia is a biodiversity hotspot, with the greatest plant diversity on severely phosphorus-impoverished soils. Non-mycorrhizal plant families (e.g., Proteaceae) feature prominently on the poorest soils, and are uncommon on richer soils.

The ecological success of Proteaceae on severely impoverished soils can be explained by two traits. Almost all Proteaceae produce cluster roots, which mobilise the scarcely-available but essential element, phosphorus. Australian Proteaceae also use phosphorus very efficiently in photosynthesis, and show a tremendous capacity to remobilise it from senescing leaves.

But the Proteaceae are only one component of the extraordinary plant diversity. Why do species with a less effective phosphorus-acquisition strategy coexist with ones that are far superior in extracting phosphorus from our extremely poor soils? Facilitation by neighbours definitely plays a role, and nutrients mobilised by Proteaceae are also used by neighbours without this strategy. It is only part of the story, however, and we are unlocking the next chapter of how native parasites (oomycetes or water-moulds) also contribute to the megadiversity in the southwest.

Professor Hans Lambers was born in the Netherlands, finished his PhD in 1979, and was appointed Professor of Ecophysiology at Utrecht University in 1985. In 1998, he migrated to Australia, where he was appointed Professor of Plant Biology/Ecology at UWA. There, he studied mineral nutrition of Australian native species, seeking to discover how some Australian plants acquire phosphorus from depauperate soil and use it very efficiently. In 2006, he established the Kwongan Foundation.

He was elected to the Royal Netherlands Academy of Arts and Sciences in 2003, and the Australian Academy of Science (2012). He received Honorary Professorships from China Agricultural University (2002), Chinese Academy of Sciences (Research Centre for Eco- Environmental Sciences, Beijing) (2004), Shenyang Agricultural University (2018), and Jiangxi Agricultural University, Nanchang, China (2019). He was appointed as Distinguished Professor at the National Academy of Agriculture Green Development at China Agricultural University (2018).

In 2018 he received the Lifetime Achievement Award of the International Society of Root Research (2018) and the John Oldham Conservation Employee Award from the Conservation Council of WA in 2019.

This annual memorial lecture is presented by the Institute of Advanced Studies and the Friends of the Grounds at The University of Western Australia and honours the life and work of Emeritus Professor George Seddon AM.

George Seddon (1927-2007) was an Emeritus Professor of Environmental Science at the University of Melbourne and a Senior Honorary Research Fellow in English at The University of Western Australia. He was a Fellow of the Royal Australian Planning Institute, the Australian Institute of Landscape Architects, the Australian Academy of Technological Sciences, and the Australian Academy of Humanities. His books include Swan River Landscapes, A Landscape for Learning and Sense of Place. He was awarded the Eureka Prize from the Australian Museum in 1995, the Mawson Medal from the Academy of Science in 1996 and a Lifetime Achievement Award from the Planning Institute of Australia.