How drones and AI could help stem the spread of a plant invading Quebec parks

Next time you're in one of Quebec's provincial parks, take a look around. Notice anything that shouldn't be there? 

You likely wouldn't, as a pesky invasive plant wreaking havoc on local biodiversity, called the common reed, holds true to its name.

The alien grass can be spotted across much of the province and the country, spreading through marshes and in ditches along highways.

Tall with a woody stem and clusters of flowers that start purple and turn wheat-coloured, the common reed can also be found in seven of Quebec's 23 provincial parks — for now. 

"The common reed is a really aggressive, invasive species, and when it arrives, it takes almost all the biodiversity," said Antoine Caron-Guay, a researcher at Montreal's Institut de recherche en biologie végétale (IRBV).

In Îles-de-Boucherville provincial park, located on a chain of islands on the St. Lawrence River between Montreal and the South Shore, large areas have been colonized by the plant, becoming giant reed beds that deprive the park's animals of food and habitat.

"There's a lot of interesting species here, and the common reed is like a threat to [them all]," said Caron-Guay. 

Quebec's highest concentration of common reed is found in the park, according to Caron-Guay. So the researcher has begun experimenting with drones and artificial intelligence to map the plant's relentless spread in hopes of nipping it in the bud — so to speak.

Before you can stop the spread of an invasive species, you need to know where it can already be found.

While the mature common reed colonies are pretty easy to spot, as the reeds can grow more than five metres tall, Caron-Guay is trying to identify the plants while they're still very young, to stop them from getting a foothold.

To conduct his field research throughout May and September of 2022, he used two large drones to take a multitude of high-resolution aerial photos, flying them through the air to map the area below in detail.

He took these photos back to a lab and fed them into an AI program that he trained to look for common reed plants from above.

Once the AI knows what it's looking for, it can analyze new photos in minutes or even seconds. Caron-Guay says his program, for which preliminary results show about 90 per cent accuracy, can be used to speed up the work of park conservation officers. 

Sophie Tessier, co-ordinator of the conservation and education service for the Îles-de-Boucherville park, agrees.