Research on the Impact of Invasives may Surprise You

Research on the Impact of Invasives may Surprise You

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The importance of eliminating invasive plants, which has long been considered settled dogma, is unsettling itself before our very eyes. 

Harvard’s Peter del Tredici is making waves among scientists and designers, though maybe not yet with ecologists, with his book Wild Urban Plants, briefly reviewed here.   He breaks the mold by looking not at a plant’s history but at the ecological services it’s currently providing in developed landscapes – like cites.

And more recently, Penn State’s report on the research results of biologist Tomas Carlo – titled “Invasive Plants Can Create Positive Ecological Change” – is getting lots of attention.

“Among conservation biologists, ecologists, and managers, the default approach is to try to eliminate and root out non-native, invasive shrubs — anything that seems to change an ecosystem,” Carlo said.  “But the problem is that most native communities already have been changed beyond recognition by humans, and many native species are now rare.”

Carlo explained that his team wanted to test whether certain well-established, invasive fruiting species have negative or positive effects on bird and fruiting-plant communities.

When he compared test sites with and without an abundance of Japanese honeysuckle, the honeysuckle proved to be a boon to fruit-eating birds.

They determined that the abundance of honeysuckle predicted the numbers and diversity of birds within the region and even beyond the region. That is, the honeysuckle and bird communities had formed a relationship known as mutualism — a term that describes how two or more species interact by benefiting mutually from each other’s existence.

Carlo argues that it’s not only expensive to try to remove invasive plants like honeysuckle – and keep them removed – but it can actually harm the newly formed balance of an ecosystem. 

His big take-away? That instead of assuming that introduced species are inherently harmful we should ask: “Are we responding to real threats to nature or to our cultural perception and scientific bias?” 

I can just imagine the heated arguments going on in faculty lounges between biologists and ecologists.   

Hat tip to Tony Avent and his February Plant Delights newsletter. Photo credit: Tomas Carlo, Penn State.

Posted by

Susan Harris
on March 7, 2011 at 5:55 am, in the category Ministry of Controversy.

    • Cyndy
    • 5th September 2017

    Hurray hurray! Sounds like real scientists – the ones still practicing old-fashioned skepticism- are looking at what all the invasives hysteria is doing to habitats and horticulture – more science please!

    • Vincent Vizachero
    • 7th September 2017
    • admin
    • 10th September 2017

    I love this too. Finally, taking the whole ecosystem and all inhabitants and their homes (cities, too, yes!) into account. Here in Colorado I have long been skeptical that some weeds on the “noxious weed list” have much more to do with that plant invading grazing areas for cattle, and effecting that industry, than anything else. About money, not biology. And people are required to spray pesticides in these areas or have it done for them (and be billed).

    • admin
    • 11th September 2017

    VV is correct, there’s a bias in such research, especially when the narrow focus is on big conspicous furry-feathery organisms that human like. In the prairie patches I study, silky bush clover forms dense clumps that crowd out many lower growing native plants. While dickey birds love nesting in the clover, all of the species, and in this case mostly invertebrates, that depend upon all those other species suffer. So it puzzles me why gardeners seem so delighted by such misleading research.

    • Joseph Tychonievich
    • 11th September 2017

    I think this makes a critically important point: the difference between non-native plants in natural ecosystems, and those in urban areas. There is no such thing as a natural urban ecosystem — urban spaces are entirely artificial environments, and I think we really need to start thinking about how to shape those ecosystems to be as healthy as possible rather than getting in arguments about natives. NOTHING is native to cities.

    • tropaeolum
    • 11th September 2017

    Years ago, I read that one of the reasons why Japanese honeysuckle shrubs are so bad is that they make songbirds more vulnerable. The shrubs provide plenty of food, but their branching habit make it easy for predators to catch birds. Songbirds eat or nest in the honeysuckle and the predators climb up and eat the birds and/or eggs.

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