「经济学人」Sleeper species

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Sleeper species Climate change could reawaken harmful invasive plants The sooner they can be weeded out, the better THE MISSION is simple. Arrive on foreign soil, blend in and wait. Then, when the time is right, emerge from the shadows and take over. This procedure, familiar from spy fiction as the preserve of sleeper agents, is also the modus operandi of certain invasive plant species. When botanists warn against invasive plants, they are usually referring to those that colonise in plain sight—a group that includes Japanese knotweed. But not all invasive species are created equal. Though some spread like wildfire from the moment they arrive, others seem content to stay put. New work suggests that conservationists ignore them at their peril. Invasive species that stay put, known as sleeper species, are not hard-wired to do so. Their natural tendency to expand is, instead, held back by some external factor. With the climate rapidly changing, Bethany Bradley at the University of Massac ………………………………