This is a troubling thread to me in far too many respects. I'll do my best to
brief.
I would argue that Mr. Cruzan misses a big point that WT points to. Species do
expand their ranges, yes. BUT, they will only do so into conditions that favor
them. Sure, speciation will create others. But, what constitutes a "successful"
species? A species, within a group, that has the largest range and broadest
niche breadth? If dispersal and random chance were the limiting factors in all
species' distributions, then "everything" would be "everywhere". How would we
be able to show in say, NMDS analyses, that ph drives a species' occurrence at
certain sites? How many species, in say, the plant kingdom, have shown to
expand their ranges northward following the retreat of glaciers, while others
languish in glacial refugium?
I couldnt agree more with the statement of preserving natural processes and not
systems. However, my understanding is that certain processes are in no way
"natural" when they are impinged upon by species that have been introduced by
man and cause immeasurable damage to trophic interactions within a normally
coevolving system. I should be ashamed as Wisconsinite to not have to the
quote tattooed on my hand, but Aldo Leopold's line about "the first rule of
intelligent tinkering is to keep all the parts". Sure, we've given up on
Dandelions, and many others, but that's CERTAINLY no reason to just throw up
our hands in "invasives" defeat. I wouldn't even begin to claim even remote
knowledge of every invaded system, but surely we could and have set parameters
on how to measure invasiveness. The idea of "pre-settlement" has changed. It's
much less of a "setting the clock back to a frontier state because we want big
trees again", and more of an idea of trying to restore SOME SEMBLANCE of a
region of working systems. Up here in the north, we clear cut EVERYTHING a
hundred years ago. South of us, there's not much left for praries, but there's
LOTS of corn and soybean farms. C'mon folks, lets be real here. The whole
sciences of Conservation Biology, Resource Management and Forestry (to name a
few) were spawned in hopes of devising ways of bringing back to some
respectable state, that which we have destroyed and denuded (or nearly so).
These sciences, as all science is designed to do, evolves.
So are we okay with deforestation of Madagascar? Should we write off Hawaii and
whats left of its endemic species? All this talk of "letting nature take its
course" smacks too much of the "god will provide" idea in the Bible.
Please correct me on or off list.
Best-
Eric
Eric North
All Things Wild Consulting
P.O. Box 254
Cable, WI 54821
928.607.3098
> Date: Sun, 11 Sep 2011 17:03:51 -0700
> From: landr...@cox.net
> Subject: Re: [ECOLOG-L] a non Ivory Tower view of invasive species
> To: ECOLOG-L@LISTSERV.UMD.EDU
>
> Ecolog:
>
> There is such a fundamental and pervasive misunderstanding of this point that
> to challenge the ecoillogical concept of "pristine" is broadly considered
> treasonous heresy. Freezing ecosystems in time has strong roots in the
> presumption that gardening and landscaping are related to ecology. I tried to
> make this point at a 1986 meeting (in Berkeley?) called "Conservation and
> Management of Rare & Endangered Plants." The reception ranged from chilly to
> freezing. One highly respected professor objected to my being permitted to
> speak at all. I no longer have an electronic copy (The Restoration of
> California: A Practical Guide), and I couldn't find one on the Internet, but
> I did find an old draft in my files. The book is available through
> bookfinder.com for fifteen bucks or so (one site has it for $240+!). Here's
> an excerpt, laboriously pecked out on my keyboard: "What's wrong with
> landscaping? Nothing is really wrong with it, but it is only cosmetic. The
> trouble is, most people think that it is natural, just like Yosemite Valley,
> and don't recognize it for what it is--an artificial decoration on the land
> that happens to be constructed of living organisms. The fact that the plant
> assemblage does not function biologically [ecologically] is lost in the
> simple lust for the desired [sic] phantasy."
>
> It is simply not widely recognized, as Cruzan points out, that ecosystems are
> not static. Many biologists and not a few ecologists apparently believe that
> they are. Again, as Cruzan says, ". . . we should focus on conserving natural
> processes, not entities." I might only add that where conditions that match
> an organism's requirements exist, the major problem will not be getting them
> to occupy such sites, but keeping them from occupying them, given the
> presence of viable propagules. But it would be the epitome of arrogance to
> declare that we know enough about ecosystems to prescribe what they should
> be--or, for that matter, what they were in the past. All we can do is to
> modify damaged sites to enable adapted (preferably indigenous) organisms to
> (re)colonize either by introducing their propagules or by watching the
> inevitable invasion.
>
> WT
>
>
> ----- Original Message -----
> From: "Mitch Cruzan" <cru...@pdx.edu>
> To: <ECOLOG-L@LISTSERV.UMD.EDU>
> Sent: Sunday, September 11, 2011 11:09 AM
> Subject: Re: [ECOLOG-L] a non Ivory Tower view of invasive species
>
>
> > I'm only asking for a quantifiable description of 'invasive' - we can't
> > do it based on where organisms originally evolved. Distributions of all
> > biota has changed dramatically in the last 18,000 years, so drawing
> > lines based on where species originally came from does not make a whole
> > lot of sense. The policy at some national parks has been to try to
> > preserve based on what we think the composition was like before the
> > arrival of Columbus to the New World. Such a view does not take into
> > account the fact that these communities are dynamic - distributions are
> > still changing in response to climate change since the last glaciation
> > (not counting human effects on climate). Distributions and community
> > composition will continue to change - these systems are naturally
> > dynamic. But this reality does not jive well with current views of
> > conservation biology whose main purpose seems to be an attempt to freeze
> > systems in time or to return them to some state that we think they use
> > to have. As conservationists we should focus on conserving natural
> > processes, not entities. Those processes lead to changes in
> > distributions, hybridization, change in community structure, and even
> > extinction. Fire policy is a great example - look at how are view of
> > the role of fire in ecosystems has changed over the last 100 years. We
> > need to have a similar recalculation of our policies for other aspects
> > of conservation biology - a focus on allowing natural processes to run
> > their course no matter where they might lead. South Florida is just a
> > great example of a dynamic system.
> >
> > So perhaps a definition of 'aggressive behavior' no matter what the
> > origin of the aggressor would be appropriate. Even then we have to make
> > decisions on if and when it would be appropriate to intervene.
> >
> >
> >
> > On 9/11/2011 10:42 AM, mcnee...@cox.net wrote:
> >> ---- Mitch Cruzan<cru...@pdx.edu> wrote:
> >>
> >> (stuff cut)
> >>
> >> What about the South Florida tropical flora/fauna? Many
> >>> species in those systems only arrived on this continent only within the
> >>> last 5000 years - are they invasive? Are entire communities in the
> >>> everglades invasive?
> >> Hmmm. How long ago did Florida emerge?
> >>
> >> Are you suggesting we should not be concerned about pythons in Florida,
> >> because though they are relative newcomers by Florida standards, all of
> >> the Floridian biota constitututes newcomers by geological standards? As
> >> another poster said, perhaps it is invasive behavior that matters. But of
> >> course, these snakes are not invasive -- they are tightly tied to the
> >> conditions where they evolved. They were brought by people, then
> >> released. But they do wreak havoc on native fauna once present. Not a
> >> problem, since Florida is recently emerged, so has only recently arrived
> >> biota?
> >> David McNeely
> >>
> >
> >
> > -----
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> >
