Isn't it Ag-gravating? The University of California's "Weed Handbook" is a veritable guide to native plants that have the temerity to try to hustle a living, casino-like, amongst the most destructive of (plant) invaders, crop monocultures. Most are not "invaders" at all, but just guerillas trying to "take back" their land.
It IS a can of worms, ain't it? WT At 07:10 AM 4/7/2006, Scott Ruhren 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' behavior >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
