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<p class=MsoNormal><span style='font-size:14.0pt;font-family:"Calibri","sans-serif";
color:black'>Greetings: I’m sorry to have come in to this discussion at this
late point, but what’s wrong with the definitions used in the Executive Order
on Invasive Species (13112), which I think are completely clear and accurate (<a
href="http://www.invasivespeciesinfo.gov/laws/execorder.shtml">http://www.invasivespeciesinfo.gov/laws/execorder.shtml</a>).
Johnny Randall<o:p></o:p></span></p>
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<p class=MsoNormal><b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>From:</span></b><span
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apwg-bounces@lists.plantconservation.org
[mailto:apwg-bounces@lists.plantconservation.org] <b>On Behalf Of </b>John Barr<br>
<b>Sent:</b> Monday, August 02, 2010 12:34 PM<br>
<b>To:</b> Bill Stringer<br>
<b>Cc:</b> apwg@lists.plantconservation.org<br>
<b>Subject:</b> Re: [APWG] Plants Alien Definition<o:p></o:p></span></p>
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<p class=MsoNormal>Wayne,<o:p></o:p></p>
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<p class=MsoNormal>Your definition for Alien appears to be workable.<o:p></o:p></p>
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<p class=MsoNormal>Your definition for Invasive is, in my opinion, uselessly
broad. Using this definition, please name an organism that is not
invasive? All organisms attempt to "exploit niches that meet
requirement for life", otherwise they die.<o:p></o:p></p>
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<p class=MsoNormal>Adding to what Bill said, alien invasive species can be
problematic not only because they have "very effective fitness
traits", but because they can arrive without their coevolved
biologic controls. Citing one local example, fire ants arrived
without phorid flies. The non native fire ants are not necessarily more
fit than native fire ant species. The natives are held in check by
coevloved controls. <a
href="http://www.sbs.utexas.edu/fireant/Research%20Program.html">http://www.sbs.utexas.edu/fireant/Research%20Program.html</a> Given
enough time (and damage to native ecosystems) some controls for the fire ant
will be expected to evolve locally. (For the record, introducing
one species to control another is something that I greatly fear. The
track record for these introductions is extremely poor. In my opinion,
much harm has been done.)<o:p></o:p></p>
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<p class=MsoNormal>Native invasives on the other hand would much more likely
arrive with their coevolved natural controls. Using Robert Layton
Beyfuss's example of native plants expanding up hillsides with climate change,
the coevolved natural controls would be expected to move with the native
invaders. An entire ecosystem would likely move upslope. This does
not change the likelihood that the higher elevation species will be displaced,
possibly to extinction, but we would not likely see the monocultures that the
most problematic alien invaders are capable of producing.<o:p></o:p></p>
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<p class=MsoNormal>So, we need to narrow the definition of invasive. This is
guaranteed to ruffle feathers. I<o:p></o:p></p>
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<p class=MsoNormal>n my opinion, the concepts of "alien" and
"invasive" are creations of people and not creations of nature.
I believe that most of us would not consider the species that arrived on
the Galapagos islands before man to be alien invaders, but certainly we would
consider those species man brought to the islands to be alien invaders.<o:p></o:p></p>
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<p class=MsoNormal>As a second pass, I would propose: An alien invasive species
is one that arrives in a new ecosystem, <i>as a result of human
intervention</i>, to the detriment of the native ecosystem. An alien
invader can benefit one or more native species, but it must be understood in
the context of the entire ecosystem.<o:p></o:p></p>
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<p class=MsoNormal>By my definition, brown tree snakes on pacific islands
invade with the direct intervention of humans (planes and boats), the native
ecosystems climbing elevation as a result of human caused climate change is an
indirect intervention, but an alien invasion none-the less. If the
climate change is not human caused, they are not alien invaders. Our
beloved armadillos in Texas are not alien invaders because they, apparently,
arrived without human intervention. <o:p></o:p></p>
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<p class=MsoNormal>Yikes,<o:p></o:p></p>
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<p class=MsoNormal>John<o:p></o:p></p>
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<p class=MsoNormal>On Aug 2, 2010, at 8:47 AM, Bill Stringer wrote:<o:p></o:p></p>
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<p class=MsoNormal>Wayne, all organisms exploit niches that meet their life
requirements. <br>
<br>
Invasive organisms invade, ie. they move in and aggressively displace
indigenous organisms and communities, thus decreasing the species
diversity. They are successful because they have 1 or more very effective
fitness traits that allow them to exploit a wide range of niche conditions, and
deny/ reduce resource availability for indigenous plants.<br>
<br>
Indigenous plants, because they have evolved in an ecosystem to be compatible
with many other species in that ecosystem, are not by nature aggressive
exploiters of resources in that "home" ecosystem.<br>
<br>
Ramble, ramble..........<br>
<br>
Bill Stringer<br>
<br>
At 05:35 PM 7/30/2010, Wayne Tyson wrote:<br>
<br>
<o:p></o:p></p>
<p class=MsoNormal><span style='font-size:10.0pt'>APWG: <br>
</span> <br>
<span style='font-size:10.0pt'>Definitions, to be useful in moving a discussion
forward as opposed to spinning its wheels in polarizing dialectics, must be
understood equally well and agreed upon by all participants. While it would
seem unnecessary to engage in such a discussion with respect to
"alien" and "invasive," I find that different posts seem to
define these key terms differently. Therefore, I will propose some definitions
(particularly as they relate to plants, but they should hold true for any
organism). I ask that responses be confined to corrections to the definitions
in the form of alternative definitions to keep the discussion from wandering
off into the intellectual weeds. Separate footnote discussions about the
reasoning that supports the definitions will be welcome, of course, but I
respectfully request that we keep it simple and stick to the subject. It is not
my intention to preserve these definitions, nor to start arguments; my hope is
that definitions will evolve that will serve to communicate these concepts
clearly. If no unanimity can be found or resolved, clarity in communication can
still be served by using modifiers to define the kind of "alien" or
"invasive" is intended. Anyone can define anything any way one wants,
but only one person may understand that definition in the same way as the
originator. <br>
</span> <br>
<span style='font-size:10.0pt'>1. <i>Alien</i> (plant or other organism). An
organism that did not evolve with other organisms in a given habitat. <br>
</span> <br>
<span style='font-size:10.0pt'>2. <i>Invasive</i> (plant or other organism). An
organism that exploits niches that meet its requirements for life. <br>
</span> <br>
<br>
<span style='font-size:10.0pt'>Relevant comments:<br>
</span> <br>
<span style='font-size:10.0pt'>1. All plants and animals reconcile their requirements
for life with environments that meet them. Invasions may occur, but the
invading organisms must "find" or create environments that are
suitable for their requirements in order to establish and maintain populations
that are able to reproduce. <br>
</span> <br>
<span style='font-size:10.0pt'>2. Environmental change is the rule, and there
are no exceptions. Change may be very fast or very slow, but nothing stays the
same. <br>
</span> <br>
<span style='font-size:10.0pt'>3. Organisms "track" changes within
their sphere of influence/capacity. <br>
</span> <br>
<span style='font-size:10.0pt'>4. Analogously, human cultures acquire places to
live in which they exclude others (aliens). In that process, other species
exploit the effects of human cultural differences. Some species of rats, for
example, have become almost entirely dependent upon human cultures for their
existence and would be restricted to non-cultivated or undeveloped habitats and
might not survive, at least in large populations, outside the boundaries of
human cultures. Certain plants have become highly dependent upon human cultures
for their existence ("crops" and "weeds"), and may have
evolved as a result, perhaps to such an extent that they could not otherwise
exist (or could be highly restricted to certain habitats) in its absence. <br>
</span> <br>
<span style='font-size:10.0pt'>I look forward to alternative definitions and
supportive reasoning and discussion. <br>
</span> <br>
<span style='font-size:10.0pt'>WT<br>
</span><br>
_______________________________________________<br>
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Disclaimer<br>
Any requests, advice or opinions posted to this list reflect ONLY the opinion
of the individual posting the message.<o:p></o:p></p>
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http://lists.plantconservation.org/mailman/listinfo/apwg_lists.plantconservation.org<br>
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