[APWG] Ecosystems Invasion resistance? Re: Do ecosystems resist invasion? Invasion and cropping Re: rate of change

Fri Mar 2 10:13:47 CST 2012

John, I ain't due no more respect than anyone else, and you have an excellent point. I took John's (Jack Ewel's) word for it (admittedly a bad practice). See Ewel, J. J. 1987. Restoration is the ultimate test of ecological theory. pp. 31-33 in: W. R.Jordan, M. E. Gilpin, and J. D. Aber (eds.). Restoration Ecology: a synthetic approach to ecological research. Cambridge University Press, Cambridge. 

Ewel's crucible was Hawaii, I believe, and if any island is more "invaded" than that place, please (I don't wanna know but I have to) let me know. If any place could test the hypothesis, that must be among the severest. 

WT

PS: I'm inserting some comments into John's text below [[thus WT]].

Suggestion: When changing the subject line, retain previous ones if relevant. 
  ----- Original Message ----- 
  From: John 
  To: apwg at lists.plantconservation.org 
  Sent: Thursday, March 01, 2012 9:02 PM
  Subject: [APWG] Do ecosystems resist invasion?

  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. 

  [[Ok, well, all generalizations have exceptions. But then, the devil is in the details, right? In ecology (lacking, as it does, laws and other absolutisms) some of us rush in where angels fear to tread and try out ideas supported by some pretty thin threads. Lacking sufficient information upon which better "conclusions" might be based, we conjecture from inference and provisionally accept the preponderance of the evidence rather than "beyond a reasonable doubt" or a "scientific certainty," at lease until better evidence shows up. Similarly, these workaday hypotheses should always remain under the gun of contrary evidence. This works us forward rather than backward. So I would put it this way: Based on what we know now, does the reasonable-man/woman standard lead one to provisionally accept the proposition that resistance to invasion is more true than untrue or more untrue than true? Then we keep testing and evaluating new information. WT]]

  Questions:
  1) How does any species ever colonize an island?  [[Let me count the ways--by wind, by wave, by ship, by flotsam and jetsam . . . WT]] Aren't the island's ecosystems as "intact" as any other? [[I dunno--maybe they're more vulnerable? WT]]
  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? [[Good question; why would they? Because we yearn for magic bullets? WT]]
  3) I fear a circular argument, invasion occurred, hence the ecosystem was not intact. [[I don't know anyone else who has made this argument. Please enlighten me. WT]]  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. [[I wouldn't argue these points, but what's your evidence? WT]]

  Enlighten me, please......is there scientific evidence for this notion? [[I look forward to your further contributions in support of the contrary. WT]]

  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 

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