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

Tue Feb 1 16:32:41 CST 2011

There’s no straw man here.  My comment below refers to a specific quote
found online at Scientific American
(http://www.scientificamerican.com/article.cfm?id=alien-invasion-ecologist-d
oubts-exotic) which says, “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 David Wilcove and
colleagues in the journal Bioscience .“  However, according to the headline
in the 1998 Davis paper, the claim is actually that invasives are the second
leading threat to biodiversity
(http://www.edf.org/documents/836_bioscience.pdf).   We need to be clear
whether we are talking about species diversity (as in species extinctions)
or biodiversity.  The terms are not interchangeable.  Biodiversity is not
limited to species diversity, rather it includes genetic diversity and
ecosystem diversity.  There is strong evidence that invasives are
drastically altering ecosystems.  

Bill Jacobs

From: Wayne Tyson [mailto:landrest at cox.net] 
Sent: Monday, January 31, 2011 6:03 PM
To: bjacobs at eeaconsultants.com; 'Holly Sletteland'; 'Marc Imlay';
apwg at lists.plantconservation.org
Subject: Re: [APWG] Exotics species overhyped,according to Feb.2011 SCI AMER
article

APWG:

I'd like to see specific comments on specific quotes from the article from
all those concerned, please. Thanks to Stringer, I've now read the
transcript of the interview. 

WT

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

From: Bill Jacobs <mailto:bjacobs at eeaconsultants.com>  

To: 'Holly Sletteland' <mailto:hslettel at calpoly.edu>  ; 'Marc Imlay'
<mailto:ialm at erols.com>  ; apwg at lists.plantconservation.org 

Sent: Friday, January 28, 2011 2:48 PM

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

It says below that Mark Davis picks apart the claim that invasive species
are the second-leading cause of extinctions.  I’ve always heard that the
second-leading cause refers to the loss of biodiversity.  Biodiversity is
more than species diversity; it includes genetic diversity and ecosystem
diversity.  I haven’t read Davis’s book, but I’m wondering if Davis makes
his case based on a false premise.  

Bill Jacobs

Senior Ecologist & Conservation Planner

EEA Inc.

1239 Route 25A, Suite 1

Stony Brook, NY 11790        

Phone: (631) 751-4600 Ÿ Fax: (631) 751-0597

From: apwg-bounces at lists.plantconservation.org
[mailto:apwg-bounces at lists.plantconservation.org] On Behalf Of Holly
Sletteland
Sent: Friday, January 28, 2011 11:34 AM
To: 'Marc Imlay'; apwg at lists.plantconservation.org
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

  _____  

_______________________________________________
PCA's Alien Plant Working Group mailing list
APWG at lists.plantconservation.org
http://lists.plantconservation.org/mailman/listinfo/apwg_lists.plantconserva
tion.org

Disclaimer
Any requests, advice or opinions posted to this list reflect ONLY the
opinion of the individual posting the message. 

  _____  

No virus found in this incoming message.
Checked by AVG - www.avg.com 
Version: 8.5.449 / Virus Database: 271.1.1/3408 - Release Date: 01/28/11
09:14:00

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.plantconservation.org/pipermail/apwg_lists.plantconservation.org/attachments/20110201/4b14f498/attachment.html>