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  • From: Mark <mpludwig@facstaff.wisc.edu>
  • To: permaculture@lists.ibiblio.org
  • Subject: Re: [permaculture] Exotic Species: #2 Cause of Extinction?
  • Date: Wed, 10 Jul 2002 10:12:47 -0500


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
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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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