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Student’s birds-eye view of Outback river tree

By Patrick Nelson

Erin Westerhuis measures the diameter of a river red gum in Alice Springs Erin Westerhuis measures the diameter of a river red gum in Alice Springs

A Charles Darwin University student has taken to the skies above Central Australia as part of a research project to examine the health of the inland Australian tree, the river red gum.

Alice Springs based environmental science student Erin Westerhuis and her supervisors took thousands of digital photos and about two hours of video footage from the seat of a helicopter during the data-gathering phase of her Honours project.

“We flew for about 25 kilometres along Roe Creek and along sections of the Palmer River at an altitude of about 50 metres,” she said.

“This was in addition to an extensive ground-level survey of the two dry waterways, during which I examined thousands of river red gums.”

Ms Westerhuis said one of her aims was to test whether assessments of river red gum characteristics from oblique aerial images accurately reflected the measurements gathered at ground level.

“This was related to a broader aim to develop a survey methodology appropriate for monitoring river red gum communities in Central Australia.”

Ms Westerhuis is concerned about the health of the river red gum (Eucalyptus camaldulensis arida), a large tree that serves as a resource and shelter for a variety of animal species in many of Central Australia’s rivers and floodplains.

“Its health and abundance has undergone an obvious decline in some parts of Central Australia,” she said.

“It would seem that the introduction of buffel grass and couch correlates with an increase in the extent and severity of fire in areas where the trees live and that this has an effect on the health and functionality of the river red gum.”

But Ms Westerhuis said a lack of baseline data meant this hypothesis was yet to be tested.

She developed a survey tool for recording vital statistics about individual river red gums, including height, trunk diameter and its location within a river system.

The survey tool also contains a section for recording the health of a particular specimen into one of eight categories, ranging from a healthy tree with a full canopy to one that is a remnant stump.

Ms Westerhuis said her research would provide land managers with a method for detecting change in the health of river red gum populations along river corridors.

The project received support from the Red Centre Biodiversity Fund.