Investigating Mulga dieback in drought

by Graeme Finlayson, Bush Heritage

A partnership between Bush Heritage Australia and Arid Recovery will investigate the impact of the recent drought in an effort to understand some long-term and future implications for biodiversity and productivity in the rangelands.

Drought conditions in the region have been well-documented, with well below average rainfall recorded in 2018-19 coinciding with long, hot summers and record temperatures. The impact of these conditions on many properties is the stark reality of a changing climate, with modelled predictions suggesting these extremes will become more common and require novel ideas for land management.

One species that appears to have suffered under the recent conditions is the Mulga, Australia’s most common tree that is long-lived and an iconic feature of much of the arid inland.

It is a species that has long been used by Traditional Owners, with its solid timber providing the perfect medium for tools. The Mulga’s seeds and gum were also used as bush food, and many native species seek shelter in its small hollows, roots or just in the shade it provides. Since European settlement, Mulga stumps have been used in pastoral infrastructure, particularly in fencing and in the building of old homesteads.

There is growing evidence the Mulga has been severely impacted by the 2018-19 drought, with many reports of widespread dieback. While it is not yet clear if the dieback is affecting a particular age class of tree or is associated with a particular land management practice, there are similar reports from previous long droughts.

However, little is understood about what drives these events and the extent of die-off and recovery. These details are important to understand, given the value of Mulga and predictions of future climatic scenarios for more frequent droughts and extreme temperatures.

The collaborative project with Bush Heritage (Bon Bon and Boolcoomatta Station Reserves) and Arid Recovery will use both ground-based surveys (collecting data from vegetation and soil plots by TERN Surveillance) and remote sensing tools (satellite imagery and drone surveys) to document the extent of Mulga deaths throughout the region.

If you have noticed dead mulgas on your property or in your region don’t hesitate to get in contact with Graeme Finlayson at graeme.finlayson@bushheritage.org.au or Kath Tuft at Arid Recovery in Roxby Downs at katherine.tuft@aridrecovery.org.au