Aṉangu knowledge and western science unlock desert plants’ survival secrets after record-breaking hot drought

A new collaborative research project between Aṉangu, the Traditional Owners of Uluṟu-Kata Tjuṯa National Park, Parks Australia and The Australian National University (ANU) and The University of Technology Sydney (UTS) has uncovered the physiological traits that helped some species of desert plants survive a mass dieback event in Australia.

A record-breaking hot drought from 2018 to 2019 caused widespread plant mortality in Uluṟu-Kata Tjuṯa National Park, Australia.

Understanding the impacts of climate change on ecologically and culturally significant plants was at the heart of the project for Aṉangu and ANU plant scientists.

Jaylen Nicholson, ANU PhD Candidate and study co-author said, “Aṉangu were concerned about these impacts and wanted to know why important plants were dying.

“This provided an opportunity to bring together Aṉangu knowledge of Country and a western plant physiology framework to better understand how culturally significant desert plants respond to extreme heat and drought.”

The results reveal the key strategies for desert plant survival in the face of increasing extreme weather events, with consequences for the conservation of ecologically and culturally important keystone species.

The team surveyed nine species of desert plants over a mild-temperature spring season and an extreme-temperature summer season and measured a range of traits for each species.

They focused on many of the keystone species in the Australian desert chosen by Aṉangu that provide food, habitat and materials for tools, including wanari (Acacia aneura, mulga), tjanpi (Triodia pungens, spinifex), and kurkara (Allocasuarina decaisneana, desert oak).

To determine why some species were more likely to survive extreme weather than others, a range of physiological traits were measured, including leaf area, leaf water content, and wood density.

The findings reveal that plants using drought-avoidance strategies were more likely to survive extreme conditions, as plant species using drought-tolerance strategies tend to have higher rates of dieback.

Drought-tolerant plants can maintain growth during dry conditions because of adaptations like dense wood and small and thick leaves, but risk severe dehydration under extreme drought.

Drought-avoiding plants conserve water by reducing growth during dry periods, but prolonged drought can exhaust carbon (stored sugar) reserves and increase mortality risk.

Maintenance of leaf relative water content, a component of drought avoidance, was the trait that best predicted dieback severity, with plants experiencing large reductions in leaf water content tending to have higher dieback severity.

However, neither strategy provided guaranteed survival under extreme drought and heat, highlighting that extreme heatwaves and drought can overwhelm all strategies that once afforded protection under droughts in the past.

“By studying ecologically and culturally important species, this research provides new insights into how plants that are important to Aṉangu respond to hotter droughts,” Mr Nicholson said.

“This knowledge can help inform culturally appropriate approaches to caring for Country as the climate continues to change.”

This project has been driven by Aṉangu aspirations and demonstrates the invaluable benefits of scientific collaboration with Indigenous communities.

“Aṉangu co-developed research aims, selected study species and locations, conducted fieldwork, and interpreted and discussed findings, ” Mr Nicholson said.

“Working together has allowed us to weave Aṉangu knowledge of Country, plants, fire, and landscape change, with a western framework of plant physiology.”

This study highlights several opportunities to reduce the impact of drought-driven dieback, including Aṉangu cultural burning and community plant nurseries.
 
“Supporting local propagation and restoration of culturally significant plants through the community nursery is an opportunity to maintain cultural connections to plants and actively restore Country,” Mr Nicholson said.

“Ultimately, however, reducing the long-term impacts of hotter droughts will require strong measures to halt and reverse anthropogenic climate change.”

Uluṟu-Kata Tjuṯa National Park Manager, Joelene Paterson said the co-designed research carried out in partnership with Aṉangu highlights the joint management principles of the park.

“Aṉangu are always caring for this Country, and we know their knowledge is vital to understanding and protecting it into the future,” she said.

“Parks Australia invested in this research as having access to good quality information that combines traditional knowledge and western science lets us make better informed park management decisions and results in stronger outcomes for Country.”

Alongside the Aṉangu co-authors, the researchers published an article in The Conversation last week outlining the broader impacts of climate change at Uluṟu-Kata Tjuṯa National Park. Aṉangu are concerned about these impacts and want people around the world to know what is happening to important plants.

This research was funded by Parks Australia, and we acknowledge the contribution of Uluṟu-Kata Tjuṯa National Park staff, the Muṯitjulu Community Mala Rangers, and other researchers from CSIRO and the University of Technology Sydney.

The study is published in Conservation Physiology.