I haven't followed the debate this week as closely as I would have liked,
but
Aren't we overlooking the inherent anthropogenic effect in alien species
introductions? Clearly, many animals play a role in introducing species to
new areas, but never in earth's
history has it occured on the scale that it has in the very recent past 500
years.
Wouldn't this simple distinction allow to decide what an alien species is?
Scott Jones
On 4/7/06, Scott Ruhren <[EMAIL PROTECTED]> wrote:
>
> Dear Ecolog readers,
>
> This could open a can of worms but... how do list members define or
> describe
> "aggressive colonizers" such as Smilax rotundifolia. This vine or
> shrub-like
> species forms dense, impenetrable patches particularly in disturbed
> suburban
> forests with a lot of sun? Though a native, much of this species' behavio=
r
> is "invasive-like." In "Weed Ecology in Natural and Agricultural Systems"
> (2003), Booth, Murphy and Swanton suggest (my interpretation) that
> "invasive" may occasionally be applied to a native increasing in
> population
> size and effect. I realize this is not popular but "weed," "invader" and
> "colonizer" still are used in often-conflicting manners.
>
> Scott
>
> ---
> Scott Ruhren, Ph.D.
> Senior Director of Conservation Programs
> Audubon Society of Rhode Island
> 12 Sanderson Road
> Smithfield, RI 02917-2600
>
> 401-949-5454
>
> -Original Message-
> From: Ecological Society of America: grants, jobs, news
> [mailto:[EMAIL PROTECTED] Behalf Of Gary Ervin
> Sent: Wednesday, April 05, 2006 11:28 PM
> To: ECOLOG-L@LISTSERV.UMD.EDU
> Subject: Re: Biology of Invasion
>
>
> Wayne:
>
> Clements actually introduced the term "invasion" in his writings on
> succession. He even at some points more or less suggested that
> "succession" is a series of "successful invasions," as I indicate to my
> Plant Ecology students. However, I broached this very general concept
> of invasion on an "Invasive Species" list a couple of years ago, and it
> was not well received.
>
> I think the best recent effort at "standardizing" definitions is:
> Richardson, D. M., et al. 2000. Naturalization and invasion of alien
> plants: concepts and definitions. Diversity and Distributions 6:93-107.
>
> They present these as terms for use in Invasion Ecology, with
> accompanying definitions (better explained in the paper):
>
> Alien species - species that have overcome geographic barriers (i.e.,
> non-native to the particular area of concern)
> Casual species - alien species that have overcome local environmental
> barriers in their new range
> Naturalized species - alien species that have overcome local
> environmental and reproductive barriers in their new range
> Invasive species - alien species that have overcome environmental,
> reproductive, and dispersal barriers in their new range, thus that they
> now readily spread and establish into either disturbed or undisturbed
> habitats
>
> Context is very important for individual species to realize their
> "invasive potential," as we all know that every species has some range
> of environmental tolerances - even invaders must fit their new habitats
> in order to invade. I'm sure list members could go on for days with
> specific examples of species that are highly invasive in some new
> regions and not in others. One great example is the Asian grass Arundo
> donax, which has caused relatively little concern here in the
> southeastern US but appears to be a huge problem in riparian areas of
> California.
>
>
> Gary
>
>
>
> ~~
> Gary N Ervin, Asst. Prof
> Biological Sciences
> PO Box GY
> Mississippi State, MS 39762 USA
>
> on the web at: http://www.msstate.edu/courses/ge14/
>
> for parcel delivery:
> Biological Sciences
> 130 Harned Biology, Lee Blvd
> Miss State, MS 39762
>
> Tel.: (662) 325-1203
> lab : (662) 325-7937
> FAX : (662) 325-7939
> ~~
>
> >>> Wayne Tyson <[EMAIL PROTECTED]> 04/05/06 5:23 PM >>>
>
> What is the definition of "invasion?"
>
> "Invasive species?" "Non-invasive alien species?"
>
> Are some (or all?) species invasive in some contexts but not others?
>
> Is "everybody" pretty much in agreement on such definitions or is
> there significant disagreement?
>
> WT
>
