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Thread: Aliens to rebuild an ecosystem?

  1. #1 Aliens to rebuild an ecosystem? 
    Forum Radioactive Isotope skeptic's Avatar
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    From New Scientist, 1 March 2014, page 40

    A new approach to restoring wilderness. In Yellowstone National Park, where elk numbers were out of control, and they were destroying all the trees, wolves were introduced, and elk numbers fell, allowing the forest to re-grow.

    This idea has now been taken up by a wide range of enthusiasts. But often, there is no predator available, or suitable grazer, where the 'natural' occupiers of those niches have become extinct. The enthusiasts are now working to introduce aliens to fill those places. So, if there is no local predator, a predator from another place may be introduced. The ultimate extreme of this approach would be lions and tigers in the prairies of North America.

    To introduce an alien species into a redeveloping ecosystem, in the hopes it will fill the ecological role of an animal now extinct - Is this scientific hubris? Is it wisdom? Is it a recipe for success or disaster?


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  3. #2  
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    The ammount of stupid threads in this forum is too damn high. alians rebuilding an ecosystem, seriously This is almost worse than the tree getting pregnant thread


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    Forum Professor Daecon's Avatar
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    Aliens in the "illegal" sense, not aliens as in spacepeople.
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  5. #4  
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    Quote Originally Posted by Daecon View Post
    Aliens in the "illegal" sense, not aliens as in spacepeople.
    Don't give it any attention. It's not very good at reading. It's one of those pathetic sock puppet trolls that will be banned shortly.
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  6. #5  
    Forum Cosmic Wizard
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    Mostly the aliens are insects and they are introduced to combat other insects which arrived accidentally.
    Examples would be Ladybugs, Praying Mantis, and Vedalia Beetles. Some of these introduced insect predators work well but a few of them have gone after insects they were not meant to affect.
    Insects have been used to control some weeds too, again generally the results are good but there have been some cases of them threatening plants they were not supposed to feed on.

    When you look at larger predators it is much harder to find ones that are restricted to a target prey species so introducing exotic predatory animals usually results in bigger problems.
    One example would be Cane Toads in Australia. They were introduced to control sugar cane beetles, but it was found they ate almost everything except sugar cane beetles.
    Another example would be cats introduced to Ellesmere Island in the Canadian Arctic. It took about 25 years for 5 cats to become more than 30,000 cats and they had to be exterminated to save native bird populations.
    In Hawaii the Mongoose was introduced and instead of eating rats like it was supposed to do it ate the eggs of native birds which it was not expected to do.

    So introducing exotic predators into an area has to be done very carefully.
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  7. #6  
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    And I give you the Australian example extraordinaire - drum roll, trumpet voluntary - The Cane Toad. Admittedly this was a cascade of aliens, the sugarcane in the first place, the pest it attracted, culminating in the introduction of a "predator" native to the original area for sugarcane. Unfortunately it wasn't a predator of that kind of insect. But it's doing a great job of wiping out Australian native animals.

    I think the only kind of "alien" predator worth considering is one which is simply a different version of the now extinct one in the region in question. So you'd use an African species equivalent to an Asian one in an equivalent environment. Or use European/North American species interchangeably.

    The biggest problem to overcome is the one highlighted by the cane toad catastrophe. A full understanding of how the ecology of the suite of species really works. Yellowstone highlights this very well. Reintroducing wolves was done mainly because it seemed "right" and there were all sorts of glaringly obvious problems from the overstocking of deer. But it wasn't a specific objective of the project to promote the growth of berry bearing shrubs and thereby make it possible for bears to extend their previously limited range.
    "Courage is what it takes to stand up and speak; courage is also what it takes to sit down and listen." Winston Churchill
    "nature is like a game of Jenga; you never know which brick you pull out will cause the whole stack to collapse" Lucy Cooke
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    Forum Radioactive Isotope skeptic's Avatar
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    Some of the enthusiasts for this process are looking back quite a way. For example, North America had the sabre tooth cats, cheetahs, horses, mammoths, mastodons and so on as wild animals. Early humans seem to have wiped them out. The enthusiasts want to introduce the equivalent, like African elephants to replace the mammoths. Lions to replace the sabre tooth cats, and so on. Is this a good idea, or a bad one, and why?
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    Is this a good idea, or a bad one, and why?
    Look at the Yellowstone example with all the "unanticipated" benefits. The biggest problem with large predators, and especially large herbivores like elephants, is the huge range of lands they need for either seasonal or constant migration. Where are the water sources that would support these animals and the prey animals? What was the ecology of interactions between these animals and the grasslands, savannah areas and forests as well as the streams, ponds and rivers that supported them? And what about "unanticipated" risks and problems.

    I've seen one short doco a couple of times about reintroducing animals to a desert area in the US. It's taking decades and they're still being fairly tentative about longer term success. Just have a look at the "Species of Concern" here - USFWS Region 3: Species of Concern List Then think about reestablishing a whole suite of herbivores, and their supporting forage and water sources, as prey animals for large predators.
    "Courage is what it takes to stand up and speak; courage is also what it takes to sit down and listen." Winston Churchill
    "nature is like a game of Jenga; you never know which brick you pull out will cause the whole stack to collapse" Lucy Cooke
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  10. #9  
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    Great grazing Greys, Batman!
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  11. #10  
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    Serendipity rules! Talking about deer. It turns out that an over abundance of deer is seriously bad for forests. It actually increases the growth of non-native shrubs and trees.


    As forests normally mature, their grasses give way to herbs and shrubs, and then new trees eventually take root. Expanding deer populations in the Northeast, however, stall forest development and promote the growth of thorny thickets of buckthorn, viburnum and multiflora rose bushes. If deer leave the forests alone, such trees as cottonwood, locust and sumac can sprout and grow unimpeded.
    The researchers found that the impacts of deer grazing on vegetation were severe and resulted in bare soil and reduced plant biomass, less recruitment of woody species and relatively fewer native species. And the deer's negative impact on seed banks resulted in significantly decreased overall species richness and relatively more short-lived species of both annual and biennial plants.
    Deer proliferation disrupts a forest's natural growth -- ScienceDaily
    "Courage is what it takes to stand up and speak; courage is also what it takes to sit down and listen." Winston Churchill
    "nature is like a game of Jenga; you never know which brick you pull out will cause the whole stack to collapse" Lucy Cooke
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