How can we protect ecosystems from invasive plants?

More than five million species of fungi are busy living a secret life in the soil beneath your feet. Just about 100,000 species are known to science, leaving a gaping hole in our understanding of the life and death role that researchers believe these tiny organisms play.

From what little we do know, the way fungi interact with vegetation can determine whether or not a non-native plant becomes invasive.  Algoma University soil ecologist Pedro Antunes aims to fine tune this knowledge, giving conservationists, land managers and others the insights they need to make informed decisions about managing ecosystems.

Antunes is particularly interested in mycorrhizal fungi, a fungal group that forms a symbiotic relationship with host plants. The mycorrhizal fungi take up residence in the plant’s roots, feeding on carbon from the plant. In return, they provide their host with essential nutrients, such as phosphorous, and protect the plant from enemies. About 90 per cent of plants form this beneficial relationship.

“Fungi form thin filaments — finer than root hairs — and can access pockets in the soil that contain water and nutrients,” says Antunes, who adds that roots are too thick to get into these tiny pockets and their reach is limited.

But these helpful fungi are not the only game in town. Other soil-dwelling fungi are pathogenic and can cause plant diseases.  The tug of war between beneficial and pathogenic fungi is where things get interesting, because it is key to understanding whether a non-native plant can take over and become invasive in communities.

As Antunes explains, plants evolve along with soil fungi — both the beneficial and pathogenic types. Research suggests that plants and fungi that have evolved together in the same area maintain a balance of sorts: pathogenic fungi have adapted to attack the plants while beneficial fungi have adapted to help them.

When a non-native plant arrives on the scene, local pathogenic fungi and beneficial fungi are not adapted to it. The new plant still forms a relationship with these fungi, but until the fungi achieve a balance between harming and helping the new plant, the plant has the potential to die off or become invasive. It is the invasive ones that most intrigue Antunes.

“So how long will it take for non-native invasive plants to acquire enemies capable of reducing their success?” he asks.

Answering that question is a fundamental part of his research and has important implications for how we prioritize management practices in natural ecosystems. In other words, when do we wait for harmful fungi to acquire strategies to attack invasive plants, and when do we spring into action with herbicides or intensive weeding?

“The question is can we be more predictive?” says Antunes. “We are learning what makes plants grow better or worse.”

Pedro Antunes

Pedro Antunes

Algoma University

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