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<DIV><FONT face=Arial>Yes, it would be interesting. For some reason, many people
in the alien bashing business seem reluctant to discuss the difference between
"invasive" plants that are largely restricted to disturbed sites and which do
not "spread" significantly into or within undisturbed ecosystems (and when
they do, attempting to understand that in those cases that the presence of the
alien or other colonizing species within "undisturbed" ecosystems is possibly
due to small areas of disturbance [e.g., gopher mounds] within them, or other
relatively short-term phenomena that shift localized habitat factors in favor of
the alien/colonizing species) and those which progressively invade undisturbed
ecosystems. It appears that Sahara mustard belongs in the latter group, but
disturbance magnifies the effect, particularly to the casual observer.
</FONT></DIV>
<DIV><FONT face=Arial></FONT> </DIV>
<DIV><FONT face=Arial>I also would be interesting to know (I haven't read the
paper; no doubt it provides this information) in which of these general
categories (I am calling them "obligate ruderals" and "true invasives," but
am willing to consider other, better terms) those included in the study fall.
Some alien species fall into both categories, still others might be considered
mere waifs. </FONT></DIV>
<DIV><FONT face=Arial></FONT> </DIV>
<DIV><FONT face=Arial>All species are likely to perform best (be most
successful) where conditions favoring their requirements are all present at the
right times, and will be less successful in more marginal habitats.
</FONT></DIV>
<DIV><FONT face=Arial></FONT> </DIV>
<DIV><FONT face=Arial>I have recently suggested that disturbances connected with
control measures such as pulling and trampling, not the mention the use of
vehicles, tend to favor many colonizing species, so won't repeat those remarks
here. </FONT></DIV>
<DIV><FONT face=Arial></FONT> </DIV>
<DIV><FONT face=Arial>I look forward to all comments, especially those revealing
my errors. </FONT></DIV>
<DIV><FONT face=Arial></FONT> </DIV>
<DIV><FONT face=Arial>WT</FONT></DIV>
<DIV><FONT face=Arial></FONT> </DIV>
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<DIV style="FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV
style="BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: black"><B>From:</B>
<A title=ialm@erols.com href="mailto:ialm@erols.com">Marc Imlay</A> </DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A
title=apwg@lists.plantconservation.org
href="mailto:apwg@lists.plantconservation.org">apwg@lists.plantconservation.org</A>
</DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Friday, March 11, 2011 2:41
AM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> Re: [APWG] NEWS: Invasive
Species Widespread,but Not More Than at Home</DIV>
<DIV><BR></DIV><!-- Converted from text/plain format -->
<P><FONT face=Arial><STRONG>It would be interesting to know if the only 2.5
sites per species in home ranges were natural sites or unnatural disturbed
sites without competition from native species. Native Switch Grass has been
found invasive in America in unnatural habitats but not in natural habitats
and is a new invasive in Europe. </STRONG></FONT></P>
<DIV><FONT face=Arial><STRONG><SPAN class=812141512-06032011><FONT
color=#0000ff> </FONT>
<P class=MsoNormal><B><SPAN style="COLOR: navy">Marc Imlay,
PhD,</SPAN></B></P>
<P class=MsoNormal><B><SPAN style="COLOR: navy">Conservation biologist, Park
Ranger Office</SPAN></B></P>
<P class=MsoNormal><B><SPAN style="COLOR: navy">(301) 442-5657
cell</SPAN></B></P>
<P class=MsoNormal><B><SPAN style="COLOR: navy"><A
title="blocked::blocked::mailto:Marc.Imlay@pgparks.com
blocked::mailto:Marc.Imlay@pgparks.com
mailto:Marc.Imlay@pgparks.com"
href="blocked::mailto:Marc.Imlay@pgparks.com" target=_blank><SPAN
title="blocked::blocked::mailto:Marc.Imlay@pgparks.com
blocked::mailto:Marc.Imlay@pgparks.com"
style="COLOR: navy">Marc.Imlay@pgparks.com</SPAN></A> <A
title="blocked::blocked::mailto:ialm@erols.com
blocked::mailto:ialm@erols.com
mailto:ialm@erols.com"
href="blocked::mailto:ialm@erols.com" target=_blank></A><A
title=blocked::mailto:ialm@erols.com href="mailto:ialm@erols.com"><A
title=blocked::mailto:ialm@erols.com
href="mailto:ialm@erols.com">ialm@erols.com</A></A></SPAN></B></P>
<P class=MsoNormal><B><SPAN style="COLOR: navy">Natural and Historical
Resources Division</SPAN></B></P>
<P class=MsoNormal><B><SPAN
style="COLOR: navy">The Maryland-National Capital Park and
Planning Commission</SPAN></B></P>
<P class=MsoNormal><B><SPAN style="COLOR: navy"><A
title="blocked::blocked::http://www.pgparks.com/
blocked::http://www.pgparks.com/
http://www.pgparks.com"
href="blocked::http://www.pgparks.com/" target=_blank></A><A
title=blocked::http://www.pgparks.com/ href="http://www.pgparks.com/"><A
title=blocked::http://www.pgparks.com/
href="http://www.pgparks.com/">www.pgparks.com</A></A></SPAN></B></P></SPAN></STRONG></FONT></DIV>
<DIV><FONT face=Arial><FONT color=#0000ff size=2></FONT> </DIV>
<P><BR><BR><STRONG>-----Original Message-----<BR>From:
apwg-bounces@lists.plantconservation.org [</STRONG></FONT><A
href="mailto:apwg-bounces@lists.plantconservation.org"><FONT
face=Arial><STRONG>mailto:apwg-bounces@lists.plantconservation.org</STRONG></FONT></A><FONT
face=Arial><STRONG>] On Behalf Of Reinhart, Kurt<BR>Sent: Thursday, March 10,
2011 11:59 AM<BR>To: apwg@lists.plantconservation.org<BR>Subject: Re: [APWG]
NEWS: Invasive Species Widespread,but Not More Than at Home<BR><BR>Okay, I'll
bite & also do some shameless self promotion.<BR><BR>A contrary view to
Firn et al. is provided using a single species (a prominent invasive tree
species) that was carried out across 40 total populations with slightly more
than half in its native range and nearly half in its non-native range in
Reinhart et al. (2010, New Phytologist </STRONG></FONT><A
href="http://onlinelibrary.wiley.com/doi/10.1111/j.1469-8137.2009.03159.x/abst"><FONT
face=Arial><STRONG>http://onlinelibrary.wiley.com/doi/10.1111/j.1469-8137.2009.03159.x/abst</STRONG></FONT></A><BR><FONT
face=Arial><STRONG>ract). This study concluded that measures of local
relative abundance were considerably greater in the non-native than native
ranges. This study may not seem like a direct comparison because the
main topic relates to Enemy release but comparable data are in the supplement
(which apparently hasn't been read by many). Others have made similar
observations though often without quantitative evidence for species like
spotted knapweed, garlic mustard, etc.<BR><BR>Firn et al's ELE study's main
advantage over Reinhart et al.'s is their use of considerably more species (26
species, 12 grass and 14 forb<BR>species) at 39 sites. They concluded
species have similar levels of abundance in native vs. non-native
ranges. A conclusion from their paper is that many of the grasses were
common at home and away while many of the forbs were rare at home and
away. However based on information in their supplement, I calculated
that on average they have measurements for only 2.5 sites per species in home
ranges and 7.6 sites per species in exotic ranges. Sampling more species
per region is valued because many species have incredibly large distributions
and local abundances are variable throughout. Sampling broadly is
necessary to avoid forms of regional sampling bias though researchers have to
balance logistics (also see Adams et al. 2009 as an example of an extensive
sampling network<BR>(</STRONG></FONT><A
href="http://www.plantecology.org/Full%20text%20papers%20and%20abstracts/2009"><FONT
face=Arial><STRONG>http://www.plantecology.org/Full%20text%20papers%20and%20abstracts/2009</STRONG></FONT></A><BR><FONT
face=Arial><STRONG>%20papers/Adams%20Bioinvasions%202009.pdf). Firn et
al. help avoid this limitation by looking at numerous species though more than
half represent relatively minor invasions.<BR><BR>I think what we would mostly
like to know is what traits/processes/interactions can we attribute to the
success of the most invasive species and whether their abundances, effects of
enemies, etc. differ at biogeographical scales. Following the rule of
10s, these species represent the most improbable invasion scenarios. So
we shouldn't be too surprised if such rare events can never be predicted
without the benefit of hindsight. However, I wouldn't be surprised if
further studies, focusing on highly invasive species which are the exceptions,
reveal that most/many are cases where the species attain greater levels of
local abundance/dominance in their non-native than native ranges. My 2
cents. You decide.<BR><BR>Kurt Reinhart<BR><BR> 31. NEWS: Invasive
Species Widespread, but Not More
Than at<BR>Home<BR> Range (Olivia
Kwong)<BR>Message: 31<BR>Date: Thu, 3 Mar 2011 08:27:30 -0600 (CST)<BR>From:
Olivia Kwong <plant@plantconservation.org><BR>To:
apwg@lists.plantconservation.org<BR>Subject: [APWG] NEWS: Invasive Species
Widespread, but Not
More<BR>Than<BR> at Home
Range<BR>Message-ID:<BR>
<Pine.LNX.4.64.1103030826390.1121@cpanel1-bb.epconline.net><BR>Content-Type:
TEXT/PLAIN; charset=US-ASCII; format=flowed<BR><BR></STRONG></FONT><A
href="http://www.sciencedaily.com/releases/2011/03/110301111459.htm"><FONT
face=Arial><STRONG>http://www.sciencedaily.com/releases/2011/03/110301111459.htm</STRONG></FONT></A><BR><BR><FONT
face=Arial><STRONG>Invasive Species Widespread, but Not More Than at Home
Range<BR><BR>ScienceDaily (Mar. 1, 2011) -- Invasive plant species have long
had a reputation as being bad for a new ecosystem when they are
introduced.<BR><BR>Stan Harpole, assistant professor of ecology, evolution and
organismal biology at Iowa State University, is founding organizer of a team
of more than 70 researchers working at 65 sites worldwide that tested that
assumption.<BR><BR>See the link above for the full article
text.<BR><BR><BR></STRONG></FONT><FONT face=Arial><STRONG></P></STRONG></FONT>
<P>
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list<BR>APWG@lists.plantconservation.org<BR>http://lists.plantconservation.org/mailman/listinfo/apwg_lists.plantconservation.org<BR><BR>Disclaimer<BR>Any
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