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Miconia calvescens is one of the world's most invasive species. Image: Forest and Kim Starr, Flickr

With its light pink blossoms and sweet purple fruit, Miconia calvescens looks innocuous enough. But those in the know aren't fooled – the plant has been identified as one of the planet's most invasive species, which helps to explain why, in some parts of the world, Miconia calvescens goes by the name 'purple plague' or 'green cancer'.

In Australia, the plant, and others like it, poses a major threat to what remains of the continent's precious rainforests and the thousands of native plant and animal species that inhabit them. It's hardy, thrives in sunlight and shade, and flowers with such gusto that mature Miconia trees can produce up to five million seeds each year – seeds that are picked up by birds or ferreted away by small mammals, further expanding its destructive reach.       

The threat posed by the 'purple plague' is serious enough that conservationists are enlisting the latest technology to help them win this biosecurity battle. As part of a collaborative venture called Project ResQu, unmanned helicopters have been taking to the skies over Queensland in an attempt to pinpoint floral invaders from the air.

"Unless detected and eradicated early, [these plants] can cause irreversible damage to our native plant and animal populations," says Dr Gary Fitt, the Biosecurity Flagship Science Director at the Commonwealth Scientific and Industrial Research Organisation (CSIRO), Australia's national science agency.

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Hunting down weeds like the 'purple plague' is much quicker and more convenient when done from the air. Image: Stefan Hrabar-CSIRO

The chopper drones were developed by CSIRO's robotics researchers, in partnership with Biosecurity Queensland, and they're able to detect invasive weeds using sophisticated imaging technology. What's more, mapping weeds that may be hiding in dense and remote rainforest terrain is much safer, quicker and more convenient when done from the air.

"In the biosecurity space effective surveillance is critical – we need to be able to detect incursions quickly and accurately. Technologies like the autonomous helicopter ... provide us with another tool in the fight against these biological invasions," says Dr Fitt.

The Project ResQu helicopters can navigate obstacles without human control while recording locations and images for biosecurity staff to scan for evidence of weeds. They're also easy to use and small enough to fit in the back of a van.

The eye-in-the-sky approach has already proved effective during surveys of rainforests in the far north of Queensland, near the city of Cairns, where the choppers detected not only Miconia but also several other weed species. 

"They performed better than expected, finding Miconia plants in dense rainforest that hadn’t been spotted before," says CSIRO robotics researcher Dr Torsten Merz. "Once the invasive plant is identified, they are removed from the rainforest." 

Top header image: Stefan Hrabar-CSIRO

Source: CSIRO