Last stands

 

Monash University is helping save Australia's iconic river red gums. Changes to river flows and relentless dry conditions have taken their toll on the majestic species, but a new monitoring program will help guide the return of precious water to where it is needed most.

Giant Eucalyptus camaldulensis or river red gums cut a familiar silhouette along the banks of Australian waterways. The trees provide an important wildlife habitat, and drought and flooding are part of their life cycle. They have cultural significance to Indigenous people and they are sought for strong and striking timber.

The largest river red gum forests in the world line the banks of the Murray and Darling Rivers. Floodplains such as Barmah Forest provide habitat for a diverse range of species and are known as the 'Kakadu of the south'. Yet up to 75 per cent of these important forests are stressed, dead or dying.

Dr Shaun Cunningham from Monash University's Australian Centre for Biodiversity is leading a satellite mapping project in a bid to save these iconic forests. Funded by the Murray Darling Basin Authority (MDBA), it has the cooperation of government agencies across three states.

"The floodplain has reached crisis point. Without substantial returns of water to the floodplain these forests will die. Red gums have survived for millennia, but the current challenge is by far their greatest," Dr Cunningham said.

Dr Cunningham explained river red gum forests often occur in pure stands on land that is frequently flooded. Increasing extraction of water from the Murray River for irrigation in the last half a century and the current dry conditions are stretching the time between floods and the trees' ability to survive.

"If we can identify those regions most at risk, environmental flows can be restored to target those areas. There is no point providing precious water to trees that are beyond saving and likewise to the stands that are coping well," Dr Cunningham said.

Dr Cunningham's team will use an extensive ground survey, remote sensing and advanced modelling methods to build a tool that predicts the condition of forests across the floodplain.

Remote sensing -- using satellites, aircraft and boats -- makes it possible to collect continuous data over large areas. Satellites fitted with sensors measure the amount of sunlight reflected from the earth's surface at different spectral bands from blue to infrared. These data can be used to determine a range of information including the amount of soil, water and vegetation.

The current model is 80 per cent accurate at predicting condition in stands outside the survey. Dr Cunningham said the ultimate aim was to build a tool that the MDBA could use to map stand condition across the whole Murray River floodplain on an annual basis.

The floodplain has reached crisis point. Without substantial returns of water to the floodplain these forests will die.

"This tool will provide accurate information on the state of the floodplain that the authorities can use to target and assess their management actions, which include environmental flows.

"This technique gives us the ability to predict vegetation conditions over vast areas."

In a separate Australian Research Council funded project, the centre will determine if this vegetation mapping can be used to predict biodiversity, in particular bird numbers, across the Murray and Darling systems.

Dr Cunningham is optimistic that with the ongoing information provided by the tool, large areas of river red gum forest can be saved with targeted flooding.

"The study actively engages all the players necessary to effect change and that's incredibly encouraging," Dr Cunningham said.

"We're contributing to science that goes beyond academia, providing accurate information to the authorities that will ultimately determine the fate of these forests. As ecologists, it is pivotal that our findings are communicated to those people who make decisions about these ecosystems.

"Perhaps the outcomes of this project will lay the foundations to ensure that future generations can enjoy the benefits of these magnificent forests."

Visit the School of Biological Sciences website for more information.