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

Kirby Fry peace at totalaccess.net
Wed Jul 10 08:11:33 EDT 2002


Hi Bob,

>> I'd like to know what you think is number one... I've always learnt that
habitat destruction is the most conclusive cause of local extinction.  <<

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."

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

>>  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.

>> 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 .

>>  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 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.

> 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.


Kirby Fry

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