Hi Scott -- I get through this conundrum by separating exotic (non-native, etc.) specie= s from invasive by characterizing invasivness as a behavior, so that both native and non-native species can behave invasively or not. It seems to clarify the difference for most people.
Betsy -- Elizabeth Rich, Ph.D. Department of Bioscience and Biotechnology Drexel University Philadelphia, PA 19104 215-895-6695 [EMAIL PROTECTED] 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: [email protected] > 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 >
