Native invasives are an important thing to acknowledge, because again the issue is not where plants are native to, but if they are invasive. Native invasives are necessarily behaving in this way due to changes in their environment (I think in the juniper's case it has to do with grazing, right?)... and in these cases - as well as with many non-native invasives, it makes sense to deal with the problem by addressing the changes in the environment (adopt better grazing practices, fire management practices, or whatever the case may be). However, I do think there are some invasive organisms that would be a problem even WITHOUT all these other human disturbances (for instance, cheatgrass)... that invade undisturbed areas and 'crash' ecosystems without being caused by environmental changes. I think that is the main reason to differentiate native invasives from introduced ones.
On Mon, Sep 12, 2011 at 9:41 AM, Wayne Tyson <[email protected]> wrote: > Warren (and others), how might the juniper "invasion" on Steen's Mountain > (or other "invasions" of indigenous species, particularly dominant, > long-lived indicators) fit into this discussion? > > WT > > > ----- Original Message ----- From: "Warren W. Aney" <[email protected]> > > To: <[email protected]> > Sent: Sunday, September 11, 2011 9:08 PM > > Subject: Re: [ECOLOG-L] a non Ivory Tower view of invasive species > > > I was speaking from a contemporary perspective, Manuel. From a very long > term perspective perhaps we can say that a species that somehow > translocated > into another ecosystem may have initially disrupted that ecosystem but > after > a few thousand generations the species and the ecosystem evolved together > to > form a coherent and mutually productive stability. There is a hypothesis > that Native Americans disrupted the American ecosystems resulting in the > extinction of several large mammal species shortly after their arrival. > But > after a few thousand generations it appears that they became a component of > the American ecosystems, sometimes managing certain ecosystem elements to > their benefit but certainly not disrupting and degrading these systems to > the extent that Euro-Americans did (and continue to do so). > > Taking your island fauna example, consider the Galapagos finches. Charles > Darwin concluded that there was probably a single invasion of a finch > species eons ago, but these finches evolved into different species so as to > fill various ecological niches, resulting in a diverse and stable set of > finch-inhabited ecosystems. Certainly introduced rats could also > eventually > evolve along with the ecosystems to become a stable component. But in the > short term that ecosystem is going to be disrupted, and in the long term > that ecosystem is going to be a somewhat different system. We humans, as > "overseers" have the ability and duty to evaluate that current disruption > and that future potential. There are those of us who say "let nature take > its course" and there are those who say "manage for human values" - I say > we > should be following the axiom of Aldo Leopold: "A thing is right when it > tends to preserve the integrity, stability, and beauty of the biotic > community. It is wrong when it tends otherwise." We need to evaluate and > manage invaders with that axiom as our beacon. > > > > Warren W. Aney > Tigard, Oregon > > > > _____ > > From: Manuel Spínola [mailto:[email protected]] > Sent: Sunday, 11 September, 2011 04:54 > To: Warren W. Aney > > Subject: Re: [ECOLOG-L] a non Ivory Tower view of invasive species > > > > Hi Warren, > > > > Take an island, you have "native" birds and later in time you have black > rats that you consider invaders, but why those "native" birds are in the > island, they needed to be invaders at some point in time. > > > > If Homo sapiens originated in Africa, from where the native Americans are > from? > > > > Best, > > > > Manuel > > > > 2011/9/10 Warren W. Aney <[email protected]> > > There can be a meaningful ecological difference between an organism that > evolved with an ecosystem and an organism that evolved outside of but > spread, migrated or was otherwise introduced into that ecosystem. An > organism that evolved with an ecosystem is considered a component that > characterizes that ecosystem. An introduced organism that did not evolve > with that ecosystem should at least be evaluated for its potential > modifying > effects on that ecosystem. > > Am I being too simplistic? > > Warren W. Aney > Senior Wildlife Ecologist > Tigard, OR > > -----Original Message----- > From: Ecological Society of America: grants, jobs, news > [mailto:[email protected].**EDU <[email protected]>] On Behalf > Of Manuel Spínola > Sent: Saturday, 10 September, 2011 12:22 > > To: [email protected] > Subject: Re: [ECOLOG-L] a non Ivory Tower view of invasive species > > > With all due respect, are not we all invaders at some point in time? > > Best, > > Manuel Spínola > > 2011/9/10 David L. McNeely <[email protected]> > > ---- Matt Chew <[email protected]> wrote: >> >> > We can compose effectively endless lists of cases where human agency has >> > redistributed biota and thereby affected pre-existing populations, >> > ecological relationships and traditional or potential economic >> > opportunities. Those are indisputable facts. >> >> The House Sparrow is in North America by human hand. >> >> >> > But what those facts mean is disputable. >> >> House sparrows are in serious decline in Europe, probably as an unintended >> consequence due to human actions. >> > >> > I see effects; they see impacts. >> > I see change; they see damage. >> >> Many people see a need to eradicate non-natives. At the same time, many >> people see a need to preserve natives. >> >> With regard to the house sparrow ------ hmmm......... . >> >> Where does the "arms race" that Matt mentioned further along in his post >> lead? >> >> mcneely >> >> > >> >> > > > -- > *Manuel Spínola, Ph.D.* > Instituto Internacional en Conservación y Manejo de Vida Silvestre > Universidad Nacional > Apartado 1350-3000 > Heredia > COSTA RICA > [email protected] > [email protected] > Teléfono: (506) 2277-3598 > Fax: (506) 2237-7036 > > Personal website: Lobito de río <https://sites.google.com/** > site/lobitoderio/ <https://sites.google.com/site/lobitoderio/>> > Institutional website: ICOMVIS <http://www.icomvis.una.ac.cr/**> > > > > > > > > -- > Manuel Spínola, Ph.D. > Instituto Internacional en Conservación y Manejo de Vida Silvestre > Universidad Nacional > Apartado 1350-3000 > Heredia > COSTA RICA > [email protected] > [email protected] > Teléfono: (506) 2277-3598 > Fax: (506) 2237-7036 > Personal website: Lobito de río <https://sites.google.com/** > site/lobitoderio/ <https://sites.google.com/site/lobitoderio/>> > > Institutional website: ICOMVIS <http://www.icomvis.una.ac.cr/**> > > > > ----- > No virus found in this message. > Checked by AVG - www.avg.com > Version: 10.0.1392 / Virus Database: 1520/3890 - Release Date: 09/11/11 > -- -- ============================ Charlie Hohn Recent Graduate Field Naturalist Program, Department of Plant Biology University of Vermont [email protected] slowwatermovement.blogspot.com
