[APWG] Do ecosystems resist invasion?
John
jmbarr at academicplanet.com
Thu Mar 1 23:02:18 CST 2012
With all due respect, and not to be a bother, but ...... I'd like to
question the notion that intact ecosystems resist invasion, but I do
not know who proposed it nor what evidence they have for it. None the
less I hear it bandied about again and again.
Questions:
1) How does any species ever colonize an island? Aren't the island's
ecosystems as "intact" as any other?
2) Fire ants like many invasives arrived in North American (and around
the globe) without their natural adversaries. How can a native fire
ant "resist" invasion when they have long developed adversaries and
the invasive species has none? This same pattern is repeated again
and again with species after species, else why would "biocontrols" be
effective or even considered?
3) I fear a circular argument, invasion occurred, hence the ecosystem
was not intact. Is there any ecosystem that is intact? Really, with
very few exceptions, if you name an ecosystem, I bet I can find: A) a
prior human impact on that ecosystem and B) a species that will
successfully invade.
Enlighten me, please......is there scientific evidence for this notion?
john in Austin
On Mar 1, 2012, at 2:49 PM, Ty Harrison wrote:
> APWG: I like Tyson's metaphor (sexist?): Whizzing up wind is what
> many of use are doing rather than using locally relevant ecological
> models as he recommends. Or as others ecologists have said: weeds
> and other invaders occupy "emtpy niches in the old corral". But
> this only goes so far. Many weeds can insinuate themselves into
> these "empty niches" in disturbance prone (drought?) ecosystems
> which we have out west (eg. Cheatgrass, Cranesbill, Star Thistle,
> Dalmatian Toadflax etc. etc. etc.). Ty Harrison
>
> ----- Original Message -----
> From: Wayne Tyson
> To: Michael Schenk ; Marc Imlay
> Cc: apwg at lists.plantconservation.org
> Sent: Wednesday, February 29, 2012 4:41 PM
> Subject: [APWG] Invasion and cropping Re: rate of change
>
> Y'all:
>
> When you change something in an ecosystem, other things change,
> including "invasions" (aka colonization). Ecosystems tend toward
> sequestering most or effectively all of the nutrients in the
> biomass--or try to. Much of colonization consists of a drive in that
> direction. This is why some ecologists have said that an ecosystem
> in equilibrium resists invasion. This is a sustained/sustainable
> situation, but that is far different from the invented and spun
> context in which "sustainable" is bandied about today.
>
> To cut to the chase, modern agronomic practice is 180 degrees out of
> phase with this principle, hence with ecosystems. Study sites where
> the best ginseng grows, and study them completely. Then compare
> those conditions with the ones in which you are attempting to grow
> it as a crop. If there is any significant difference, it is likely
> that you are whizzing upwind.
>
> This is already indulging in more conjecture than justified by the
> scant information about the ecological context of your project, so
> take it with a grain of salt and see if any of the principles
> mentioned help. I hope so.
>
> WT
>
>
> ----- Original Message -----
> From: Michael Schenk
> To: Marc Imlay
> Cc: apwg at lists.plantconservation.org
> Sent: Tuesday, February 28, 2012 4:21 PM
> Subject: [APWG] rate of change
>
> Bingo! It's the rate of change that counts. When a new species
> arrives every thousand years, a time scale roughly consistent with
> "natural" climate change disturbances, the ecosystem has a chance to
> respond and integrate the new species.
>
> If you keep on rocking the boat and never give it a chance to steady
> out, somebody's gonna get wet. Sometimes I feel like we're arguing
> over angel dancing space. The fact is, the boat is swamping, and we
> need to slow down the rate of change.
>
> I'm a small landholder, trying to plant sustainable harvests of
> ginseng, etc., in the face of encroachment from garlic mustard,
> stiltgrass, tearthumb. I don't have the time or resources for
> massive intervention. I need affordable, time-efficient methods of
> non-toxic removal. I've already spent hundreds of hours and many
> dollars on weedwhackers and native seed. For me, the combination of
> mechanical removal and planting native grasses is at least holding
> the stiltgrass steady. I'd like to learn about other successful
> practices that fit with a modest budget and a working schedule.
>
> Cheers,
> Mike
>
> -----Original Message-----
> From: Marc Imlay
> Sent: Feb 28, 2012 7:35 AM
> To: "'Hempy-Mayer,Kara L (CONTR) - KEC-4'" , apwg at lists.plantconservation.org
> Cc: rwg at lists.plantconservation.org
> Subject: Re: [APWG] [RWG] Ecosystem Restoration Collapse
>
> Just to clarify, ecosystems are dynamic and constantly changing, but
> not at the present rate of change. When endangered species were
> protected with national and international laws and programs several
> decades ago, we agreed that species naturally become extinct over
> time. It is just the rate of extintion that had increased a thousand
> fold and needed to be reversed so new species had an ecosystem to
> evolve in.
>
> Marc Imlay, PhD,
> Conservation biologist, Park Ranger Office
> (301) 442-5657 cell
> ialm at erols.com
> Natural and Historical Resources Division
> The Maryland-National Capital Park and Planning Commission
> www.pgparks.com
>
>
> From: apwg-bounces at lists.plantconservation.org [mailto:apwg-bounces at lists.plantconservation.org
> ] On Behalf Of Hempy-Mayer,Kara L (CONTR) - KEC-4
> Sent: Monday, February 27, 2012 2:14 PM
> To: 'apwg at lists.plantconservation.org'
> Cc: 'rwg at lists.plantconservation.org'
> Subject: Re: [APWG] [RWG] Ecosystem Restoration Collapse
>
> Agreed. I’ve heard many people argue against the ideas of
> “ecosystem preservation” and “restoration,” but it’s usually a
> matter of semantics. What restoration and preservation are trying
> to accomplish is to maintain diversity on a global scale: there are
> ecosystems here that worked well before we starting impacting them
> so profoundly: we attempt to “restore” them by taking out what we
> put in (exotic weeds), or trying to repair what we damaged (soil
> structure, hydrology, etc.). Then, hopefully, the previous
> ecosystem processes can reestablish.
>
> As to the argument about increased carbon dioxide levels: I’ve
> always wondered about this. The argument that increased CO2 in the
> atmosphere has a profound effect on plant growth assumes that
> nothing else is limiting plant growth. From my limited background in
> plant physiology, there are usually many things limiting plant
> growth: macronutrients, micronutrients, water, and light. In
> balance, can CO2 have that big of an effect, even if it is limiting?
> Are there field studies that have found evidence for this?
>
> Thank you for the opportunity to comment -Kara
>
> From: apwg-bounces at lists.plantconservation.org [mailto:apwg-bounces at lists.plantconservation.org
> ] On Behalf Of William Stringer
> Sent: Monday, February 27, 2012 8:41 AM
> To: Robert Layton Beyfuss; Katie Fite; Wayne Tyson
> Cc: apwg at lists.plantconservation.org; rwg at lists.plantconservation.org
> Subject: Re: [APWG] [RWG] Ecosystem Restoration Collapse
>
> As to ecosystem restoration , we are not proposing to make a man-
> made Hope Diamond here. We are proposing to work from our
> admittedly limited knowledge base of what should be there, and what
> should not. We take out, to the degree that we can, the should-
> nots, particularly the known exotic invasive should-nots. We then
> try to place into the site local-source propagules of known natives
> in a patchwork of mixtures of relatively compatible species. At
> that point we have probably done most of what we can contribute. We
> can manage the site to the degree that we can simulate natural
> disturbance phenomena. But mostly at this point we stay out of the
> way and let natural phenomena drive the restoration. The only
> exception would be if outbreaks of exotic invasive species begin to
> threaten. Then, we monitor and learn
>
> What we cannot do is let micro-analysis of the term restoration
> immobilize us into total inaction.
>
> Bill Stringer
> From: apwg-bounces at lists.plantconservation.org [apwg-bounces at lists.plantconservation.org
> ] On Behalf Of Robert Layton Beyfuss [rlb14 at cornell.edu]
> Sent: Monday, February 27, 2012 10:26 AM
> To: Katie Fite; Wayne Tyson
> Cc: apwg at lists.plantconservation.org; rwg at lists.plantconservation.org
> Subject: Re: [APWG] [RWG] Ecosystem Restoration Collapse
>
> I do not understand how ecosystems can be restored since I consider
> them as dynamic and constantly changing. It is not possible to
> completely re-create the environmental conditions that led to a
> given ecosystem at any given time in the past. If ecosystems
> represent the interactions of living and environmental factors, to
> restore an ecosystem requires replicating the previous environmental
> factors that affect the living organisms. The level of carbon
> dioxide in our atmosphere has doubled in the past 80 years. Plant
> growth, reproduction and survival is profoundly affected by carbon
> dioxide levels. I consider attempts to restore ecosystems as no
> more than human’s creating new ecosystems using species of plants
> that previously occurred because humans liked the previous once more
> than the current one.
>
> From: apwg-bounces at lists.plantconservation.org [mailto:apwg-bounces at lists.plantconservation.org
> ] On Behalf Of Katie Fite
> Sent: Monday, February 27, 2012 9:12 AM
> To: Wayne Tyson
> Cc: apwg at lists.plantconservation.org; rwg at lists.plantconservation.org
> Subject: Re: [APWG] [RWG] Ecosystem Restoration Collapse
>
> Wayne,
>
> I am interested in the discussion.
>
> And discussions of what ecological restoration is, and also
> discussions of how the term "restoration" is currently being used by
> agencies or at times industry - to describe imposing major
> disturbances on mature or old growth woody vegetation communities -
> with such disturbances often then leading to weed invasions.
>
> Katie Fite
>
>
>
> _______________________________________________
> PCA's Alien Plant Working Group mailing list
> APWG at lists.plantconservation.org
> http://lists.plantconservation.org/mailman/listinfo/apwg_lists.plantconservation.org
>
> Disclaimer
> Any requests, advice or opinions posted to this list reflect ONLY
> the opinion of the individual posting the message.
> No virus found in this message.
> Checked by AVG - www.avg.com
> Version: 10.0.1424 / Virus Database: 2113/4840 - Release Date:
> 02/28/12
>
> _______________________________________________
> PCA's Alien Plant Working Group mailing list
> APWG at lists.plantconservation.org
> http://lists.plantconservation.org/mailman/listinfo/apwg_lists.plantconservation.org
>
> Disclaimer
> Any requests, advice or opinions posted to this list reflect ONLY
> the opinion of the individual posting the message.
> No virus found in this message.
> Checked by AVG - www.avg.com
> Version: 2012.0.1913 / Virus Database: 2114/4844 - Release Date:
> 03/01/12
>
> _______________________________________________
> PCA's Alien Plant Working Group mailing list
> APWG at lists.plantconservation.org
> http://lists.plantconservation.org/mailman/listinfo/apwg_lists.plantconservation.org
>
> Disclaimer
> Any requests, advice or opinions posted to this list reflect ONLY
> the opinion of the individual posting the message.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.plantconservation.org/pipermail/apwg_lists.plantconservation.org/attachments/20120301/3f70f365/attachment.html>
More information about the APWG
mailing list