[APWG] Exotics species overhyped, according to Feb.2011 SCI AMER article

Tue Feb 1 11:58:25 CST 2011

Well, I think that credentials typically imply some level of competence.  I
was also hoping that someone with credentials, might see more flaws in his
position than I do.  I don't think there is any disagreement with his basic
premise that most nonnative species are not problems and  "These days, more
than ever, we need to spend society's fiscal resources wisely and
strategically".  That is why non-native species are evaluated and if
determined to be invasive, are rated according to relative risk.  But at a
time when the public is finally waking up to the fact that many non-native
species are causing severe problems, his general derision of those who are
trying to work on those problems is disturbing to me.  I don't think
invasives species are "over-hyped" by any means. On the contrary, I don't
think they get the attention they deserve.

More specifically, his statement that "The problem I have is that species
are not health threats, are not causing any significant economic cost, yet
people claim that they have undesirable ecological effects.The fact that
native species may become less abundant, is that really harm, or is that
just change?"  He contends that science should not be motivated by values,
and yet obviously this statement values human impacts above other impacts.
I'm more familiar with invasive plants and  I think that most people that
are concerned with invasive weeds have made a clear distinction between
non-native species that have simply escaped their natural range and those
that are causing ecological harm - with the loss of native species being one
significant indicator of harm, but increased fire, erosion, water
consumption, etc. being among the many other factors considered. The
secondary impacts to wildlife caused by monocultures of weeds has also been
well documented.  It causes a significant loss of habitat, which to my
knowledge is the leading cause of extinction.  It's not only development
that destroys habitat. So yes, if you don't value native plants and animals,
then I guess invasive weeds aren't a problem, unless they are bad for your
health or your pocketbook.   He makes an exception for islands, noting that
the brown tree snake has wrecked havoc on some islands and is a major threat
to species survival. Has he not heard about the "island effect" - that we
have so fragmented natural areas that we have created islands everywhere?
He completely dismisses the "precautionary principle", noting that the world
is constantly changing and we can't predict what will happen, as if that is
a reason not to exercise some caution and humility.  In the next breath he
mentions climate change, which scientists have been predicting with
reasonable accuracy what the effects will be.  He also dismisses scientific
work identifying invasive traits as not being very successful, and yet I
would aver that they have been very successful.  

Those are some of the things I take exception to, but I have a grant
proposal to write.

From: Wayne Tyson [mailto:landrest at cox.net] 
Sent: Monday, January 31, 2011 7:04 PM
To: Holly Sletteland; 'Marc Imlay'; apwg at lists.plantconservation.org
Subject: Re: [APWG] Exotics species overhyped,according to Feb.2011 SCI AMER
article

It's not credentials that are needed, it's competence. But when he's taken
on, it should be in the open, and with the courage to see it through.
Alternatively, this list could discuss it based on the actual specifics of
what he said, not by setting up straw-men. 

WT

----- Original Message ----- 

From: Holly Sletteland <mailto:hslettel at calpoly.edu>  

To: 'Marc Imlay' <mailto:ialm at erols.com>  ; apwg at lists.plantconservation.org

Sent: Friday, January 28, 2011 8:34 AM

Subject: Re: [APWG] Exotics species overhyped,according to Feb.2011 SCI AMER
article

I subscribe to Scientific American and was very dismayed to see that
article.  It takes a highly anthropogenic view of invasive species,
contending that we should only worry about them if they cause harm to the
economy or health and learn to live with most everything else.  He
acknowledges that some species have proven ecologically harmful, but
downplays it, focusing instead on the supposed exaggeration of environmental
impacts.  Scientific American is very widely read. I would hope that someone
with more impressive credentials than myself would take him to task for this
article in a letter to the editor.

From: apwg-bounces at lists.plantconservation.org
[mailto:apwg-bounces at lists.plantconservation.org] On Behalf Of Marc Imlay
Sent: Thursday, January 27, 2011 5:02 PM
To: apwg at lists.plantconservation.org
Subject: Re: [APWG] Exotics species overhyped, according to Feb.2011 SCI
AMER article

Regarding "the exotic plant is considered a critical habitat for endangered
bird species, such as the
<http://www.scientificamerican.com/blog/60-second-science/post.cfm?id=biolog
ists-arent-keeping-track-of-e-2009-05-27> southwestern willow flycatcher
that nests in its branches." so was the native cottonwood and willow trees
replaced by the salt cedar critical habitat for the bird (There was only one
listed endangered bird species, not several as implied).  We have to replace
the salt cedar that we remove with the original natives. In this case one of
the benefits of the native ecosystem was retained by the exotic ecosystem
but other benefits were lost. The biological control can be released where
the endangered bird is not present but only mechanical and herbicidal
control should be used where the endangered bird is surviving, and only
gradually while the native trees grow up and support the endangered bird.
The same phenomena occurred in Hawaii when the birds that endangered plants
depended upon became extinct (because of us). It became necessary to retain
non-native birds that the endangered plants need. We chose a less invasive
species of bird to retain that worked for the plants. 

Regarding "There have been thousands of nonnative species introduced in the
United States," he says, "and they have not caused one native species to go
extinct.", Davis is incorrect. While it is true that invasive plant species
alone on the mainland have caused few extinctions the same can be said for
other causes. It is the cumulative impact that generally causes extinction.
Examination of endangered and extinct species has shown that replacement by
monocultures occurs over a significant portion of the ranges of about 40% of
endangered species.   For example, in a paper by Sam Fuller and myself, we
did a field survey of the endangered mussel, Elliptio waccamawensis, in
North Carolina We found that the invasive Asiatic clam, Corbicula
manilensis, replaced the native mussels which we found dead on the banks but
only where the creeks were disturbed by the Army Corps of Engineers. Where
the Asiatic clam had not yet reached the disturbed habitat the mussels
survived. The Asiatic Clam was present, but in a much lower density, in
pristine unpolluted habitat and the mussels also survived. Fuller, S. L. H.
and M. J. Imlay. 1976. Spatial competition between Corbicula 
manilensis (Philippi), the Chinese clam (Corbiculidae), and the freshwater
mussels (Unionidae) in the Waccamaw River basin of the Carolinas (Mollusca:
Bivalvia). Association of Southeastern Biologists, Bulletin 23(2):60. 

[Abstract]

            Dead mussel shells and abundant living Corbicula manilensis
(Philippi, 1841) were found below the confluence of the Waccamaw River with
the intracoastal Waterway (Horry County, South Carolina), where the river is
profoundly disturbed by human activities. Above this confluence, where the
river is, in general, little disturbed, mussels were found increasingly
dominant over C. manilensis, as samples were taken further upstream, until
the latter disappeared. C. manilensis reappeared in Lake Waccamaw (Columbus
County, North Carolina), but mussels persisted in apparently diminished
numbers. The lake is almost encircled by extant and potential land
development, but its floor remains negligibly damaged. It appears that C.
manilensis does not (and perhaps cannot) dominate indigenous bivalves in
nearly or quite natural habitats, at least in slowly moving, soft bottom
Coastal Plain streams of the Atlantic drainage. Corollarily, not to disturb
aquatic habitats may be man's best defense against domination of the benthos
by C. manilensis. 

Cheers.

Marc Imlay, PhD,

Conservation biologist, Park Ranger Office

(301) 442-5657 cell

 <mailto:Marc.Imlay at pgparks.com> Marc.Imlay at pgparks.com ialm at erols.com

Natural and Historical Resources Division

The Maryland-National Capital Park and Planning Commission

www.pgparks.com

 Alien Invasion? An Ecologist Doubts the Impact of 

Exotic Species

Many conservationists have dedicated their lives to eradicating invasive
plant and animal species, but Mark Davis wants them to reassess their
missions

By  <http://www.scientificamerican.com/author.cfm?id=1575> Brendan Borrell
| August 14, 2009 |
<http://www.scientificamerican.com/article.cfm?id=alien-invasion-ecologist-d
oubts-exotic&page=2#comments#comments> 43 

As Chew and his co-authors point out in the March issue of
<http://www3.interscience.wiley.com/journal/122240688/abstract> Restoration
Ecology, salt cedar was just a scapegoat in the
<http://www.scientificamerican.com/topic.cfm?id=water> water wars that have
gripped the Southwest. Today, many early claims have been refuted and the
exotic plant is considered a critical habitat for endangered bird species,
such as the
<http://www.scientificamerican.com/blog/60-second-science/post.cfm?id=biolog
ists-arent-keeping-track-of-e-2009-05-27> southwestern willow flycatcher
that nests in its branches.

In his book Davis picks apart the claim that invasive species are the
second-leading cause of extinctions. He traces that meme back to a 1998
paper by Princeton ecologist
<http://www.princeton.edu/step/people/faculty/david-wilcove/> David Wilcove
and colleagues in the journal Bioscience, which he derides for being based
on the "opinions" of field researchers. Moreover, most species said to be
imperiled by invaders were located in Hawaii and on other islands, not the
mainland U.S., where he is skeptical that alien species can gain a foothold.
"There have been thousands of nonnative species introduced in the United
States," he says, "and they have not caused one native species to go
extinct."

 -----Original Message-----
From: apwg-bounces at lists.plantconservation.org
[mailto:apwg-bounces at lists.plantconservation.org] On Behalf Of Craig Dremann
- Redwood City Seed Company
Sent: Tuesday, January 25, 2011 8:32 PM
To: apwg at lists.plantconservation.org
Subject: [APWG] Exotics species overhyped,according to Feb.2011 SCI AMER
article

Dear All,

February 2011 Scientific American article, page 74-77 "A Friend to Aliens,

by Brendan Borrell, an interview with Mark Davis of Macalester College in

St. Paul MN.

Sincerely,  Craig Dremann

  _____  

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