Wayne, as I understand the situation western junipers in the northern Great Basin are a native species once "managed" by naturally recurring wildfires. Fire control has allowed this species to increase in density and occurrence, dominating landscapes where it was once only spotty and localized. I'm sure there are other instances where human intervention has resulted in unintentional changes to native species mixes and relationships. In this case, junipers are not really invasive on a landscape scale since they were long time natives -- maybe "intrusive" would be a better descriptor.
Warren W. Aney. -----Original Message----- From: Ecological Society of America: grants, jobs, news [mailto:[email protected]] On Behalf Of Wayne Tyson Sent: 12 September, 2011 06:41 To: [email protected] Subject: Re: [ECOLOG-L] a non Ivory Tower view of invasive species 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]] 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/> 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/> Institutional website: ICOMVIS <http://www.icomvis.una.ac.cr/> ----- No virus found in this message. 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