[permaculture] Exotic Species: #2 Cause of Extinction?

Mark mpludwig at facstaff.wisc.edu
Wed Jul 10 11:12:47 EDT 2002


>
>An educated guess is that agriculture is the leading cause of habitat
>destruction / species extinction.  Since many of our food plants in North
>America come from other continents it's hard for me to distinguish ag from
>"exotics."

I would guess that today housing development gives ag and close 
2nd.  Chemical use and disturbance are higher in the burbs than in ag 
fields where economics constrain actions to a larger degree.  This is in no 
way saying ag is not significant.

>An interesting statistic to know would be what is the largest crop in the
>U.S.A?  Wheet, corn, soy bean, cattle?

Hard to break it out so cleanly given that most ag fields rotate through a 
series of crops.  A better assessment of the damage done might be to look 
at the prevalence of large monocroped areas vs farms maintaining fence rows 
or polycultures like hay or pasture.  Another might be relative niche size 
for other animals ie tilled fields vas permanent pasture.

> >>  Species extinction has to be assessed on a species/habitat by
>species/habitat basis. Habitat and species are for all reasonable purposes
>inseparable.  <<
>
>Agreed, and that's why I'm attempting to track down the study that makes the
>above claim.  I'd like to know exactly what exotics are we talking about and
>exactly what species have become extinct as a ersult of their invasiveness.
>As a matter of fact, the friend of mine who was quoting this study told me
>that he heard about it from a range science professor, Dr. Fred Smeins, at
>Texas A & M University in College Station, Texas.  I've got a book with some
>of his work in it and will be going through it ASAP.

Also relative invasiveness or damage potential of a given species.  Quack 
grass is invasive but has probably saved more soil from eroding than all 
conservation programs combined; probably a net plus for the 
ecosystem.  Zebra mussles clear water very effectively but tend to knock 
the food chain pretty hard and clog infrastructure, net negative.  God help 
us if the Asian wood borer really gets rolling, say goodbye to a large 
number of hardwoods.

> >> Habitat size and isolation are the primary determinants of extinction
>risk. Small isolated islands with a unique species of flightless dodo's are
>always primarily at risk. <<
>
>Fragmentation puts a lot of things at risk.  When one performs a controlled
>burn on a field it's often surrounded by nothing bu roads and development,
>so it's all too easy to burn the entire field and wipe out the entire insect
>community and leave no mosaic of unburned sanctuary .

Education is the key here.  In the decade I've been doing burns attention 
to this has gone from near zero to 80% or better.  We do learn, thank 
goodness.

> >>  On islands the cause of extinction can be the invasion of a new species
>and this in turn is due to some disturbance - the visit of a ship, a
>wildfire, a new road or bushwalking track.  <<
>
>It seems that by not including exotics as a form of human interferance, or
>rather by giving it it's own category, we are able to point the finger at
>the exotic species all too easily and not ourselves.  It often requires a
>severely disturbed landscape for an exotic to gain a foot hold as well as
>some human vector for getting the exotic pest species from point A to point
>B.

I agree with the vector part, but see a lot of these critters moving into 
relatively undisturbed areas, esp. the case with animals and insects.

>I believe the motive behind putting exotics as the nuber two cause of
>extinction , at least from a university stand point, is to single out the
>exotic plant communities in order to promote the use of chemical herbicides,
>chem companies being huge sponsors of university graduate programs.
>
>So to those folks all too eager to jump on the anti-exotics band wagon,
>beware, I say, because you may be playing the fool for companies like Dow
>and Monsanto.  Round-up is a prime example of an herbicide used to remove
>Johnson grass and Bermuda grass for prairie restoration projects.

There is generic roundup these days.  I'm all for a little spray here and 
there to get the job done.  There is simply to much to do and not enough 
labor to do it to be trying to knock back this problem without poisoning 
some of our foes.  Wether or not this is some kind of conspiracy is of 
little concern to me frankly.

> > 1. Work from the 'good' areas to the bad
> > 2. Minimize disturbance
> > 3. Work at a rate of natural replacement. i.e. don't weed faster than
> > the bush will naturally regenerate - fill the holes you've left.
> > Variations on this theme are pratcied to good effect by local councils
> > thorughout Australia.
>
>This sounds like some good solid advise.  My work partner and I have been
>wracking our brains as to a means for exotics reduction without creating
>further disturbance and perpetuating the "reinfestation" of undesirable
>exotics.  Our best "theories" yet, are to use a radionic field broadcaster,
>and bio-dynamic prep's to reduce the potency of the invader, follow up by
>feeding the soil food-web with micorisal inoculates, and food sources for
>the other soil microbes and a no-till drill for seeding the desirable native
>species.  This is nothing but theory at the moment, but worth contemplating.
>
>Thanks for your input, Bob.

There is some good work on using natural soil based pathogens on Canada 
thistle in out area.  Basically all one needs to do is mow them in the rain 
and enough psudomonus gets into them to make them quite ill.  I'm sure such 
solutions are out there for many of these problem organisms, forums like 
this may be a key to spreading the word.  But I for one will keep all the 
tools at my disposal, including a spot of poison, ready for action.
Mark


>Kirby Fry
>
>For the real scoop on environmental and social justice issues check out the
>archives of Democracy Now!
>http://www.webactive.com/webactive/pacifica/demnow/archive.html
>
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Mark P. Ludwig
Poultry Research Lab
University of Wisconsin -Madison
608-262-1730 WK
608-846-7125 HM




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