How invasive species (slowly) push plants toward extinction

Discussion in 'Earth Science' started by Plazma Inferno!, Aug 29, 2016.

  1. Plazma Inferno! Ding Ding Ding Ding Administrator

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    Japanese knotweed. Purple loosestrife. Kudzu. Mesquite. Giant hogweed. Bitou bush. What do all of these plants have in common? Easy: they’re all among the most invasive plant species on the planet. Wherever they turn up, native species often get squeezed out and pushed toward extinction.
    But, unlike invasive predators such as rats and cats, have these invasive plants ever actually cased another plant species to go extinct? The authors of a new paper, published earlier this month in the journal AoB Plants, said invasive plants pose a global threat, but they weren’t able to document any confirmed native plant extinctions caused by these invaders.
    The main reason why there is no clear evidence of extinction that can be exclusively attributed to plant invasions is that invasions have not been around long enough. New research shows that plant extinction is an agonizingly slow process. However, red flags are evident in numerous locations around the world—species that now exist in fragmented populations, with radically reduced opportunities to reproduce.
    Researchers from the University of Canberra looked at these “red flags” and came up with a six-point “extinction trajectory” for native plant species facing threats from invasive vegetation:
    1. Plants die quicker than they can be replaced by their offspring in some locations.
    2. Plants disappear from some locations entirely, but potential offspring remain as “propagules,” seeds or spores that could regenerate a new cohort of individuals.
    3. Some locations lose both individual plants and their propagules. With no plants or seeds, this is a local extinction.
    4. The last locations hosting a species lose their individual plants, but in some places seeds or spores remain in the soil.
    5. The species is entirely lost in the wild with no individuals or propagules. The only survivors are held in botanic collections.
    6. Extinction. The remaining plants are lost, and the remaining seeds or spores are no longer capable of becoming new plants.
    http://blogs.scientificamerican.com/extinction-countdown/invasive-plants/
     

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