Invading species can extinguish native plants despite recent reports

January 9, 2013
Native plants on a California reserve (in yellow bloom on mound at right in background) are found in a marginal, patchy habitat following invasion by exotic grasses (in green at foreground). Ecologists at the University of Toronto and ETH Zurich have found that, given time, invading exotic plants will likely eliminate native plants growing in the wild despite recent reports to the contrary. Credit: James Cornwell

Ecologists at the University of Toronto and the Swiss Federal Institute of Technology Zurich (ETH Zurich) have found that, given time, invading exotic plants will likely eliminate native plants growing in the wild despite recent reports to the contrary.

A study published in (PNAS) reports that recent statements that are not problematic are often based on incomplete information, with insufficient time having passed to observe the full effect of invasions on native biodiversity.

"The impacts of exotic plant invasions often take much longer to become evident than previously thought," says Benjamin Gilbert of U of T's Department of Ecology & Evolutionary Biology (EEB) and lead author of the study. "This delay can create an 'extinction debt' in native plant species, meaning that these species are slowly going extinct but the actual extinction event occurs hundreds of years after the initial invasion."

Native plants on a California reserve (in bloom on mounds in background) are found in marginal, patchy habitats following invasion by exotic grasses (in green in foreground). Ecologists at the University of Toronto and ETH Zurich have found that, given time, invading exotic plants will likely eliminate native plants growing in the wild despite recent reports to the contrary. Credit: James Cornwell

Much of the debate surrounding the threat posed to biodiversity by the invasions of non-native species is fueled by recent findings that competition from introduced plants has driven remarkably few plant species to extinction. Instead, native in invaded ecosystems are often relegated to patchy, marginal habitats unsuitable to their nonnative competitors.

However, Gilbert and co-author Jonathan Levine of ETH Zurich say that it is uncertain whether the colonization and extinction dynamics of the plants in marginal habitats will allow long-term native persistence.

"Of particular concern is the possibility that short term persistence of native flora in invaded habitats masks eventual extinction," says Levine.

The researchers conducted their research in a California reserve where much of the remaining native plant diversity exists in marginal areas surrounded by invasive grasses. They performed experiments in the reserve and coupled their results with quantitative models to determine the long term impacts of invasive grasses on .

"Invasion has created isolated 'islands of native plants' in a sea of exotics," says Gilbert. "This has decreased the size of native habitats, which reduces seed production and increases local extinction. It also makes it much harder for native plants to recolonize following a local extinction."

"Our research also allows us to identify how new habitats for native flora could be created that would prevent from happening. These habitats would still be too marginal for invaders, but placed in such a way as to create 'bridges' to other patches," says Gilbert.

Explore further: Using computer models to help our fragile ecosystem

More information: The findings are reported in the paper "Plant invasions and extinction debts" in PNAS' Early Edition this week.

Related Stories

Using computer models to help our fragile ecosystem

September 25, 2012

Global warming is well-known for its effect on the climate. But it also poses a threat to the world's ecosystems. University of Toronto researcher Benjamin Gilbert wants to know more about that process.

Recommended for you

Canada conservationist warns of 'cyber poaching'

February 25, 2017

Photographers, poachers and eco-tour operators are in the crosshairs of a Canadian conservationist who warns that tracking tags are being hacked and misused to harass and hunt endangered animals.

How proteins reshape cell membranes

February 24, 2017

Small "bubbles" frequently form on membranes of cells and are taken up into their interior. The process involves EHD proteins - a focus of research by Prof. Oliver Daumke of the MDC. He and his team have now shed light on ...

Neanderthal DNA contributes to human gene expression

February 23, 2017

The last Neanderthal died 40,000 years ago, but much of their genome lives on, in bits and pieces, through modern humans. The impact of Neanderthals' genetic contribution has been uncertain: Do these snippets affect our genome's ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.