all theory thread DESIGN PRINCIPLES used in our course notes.

mangodance bmn at
Tue Aug 29 20:59:38 EDT 2000

Toby Hemenway wrote:
> Ava makes a good point about non-native food plants. How many people live on
> native foods? And agri-biz is the number one source of habitat loss.
> Permaculture's self-reliant designs are a superb answer to that problem, by
> locating useful exotics in our yards. This could allow some mega-farms to
> return to wild land.
> Since many permies come from an ag or an enviro background, the
> native/exotic edge is an abrasive and noisy one for us. We've been trained
> to despise non-natives, yet I think permaculture's attitude toward "exotics"
> offers a realistic strategy for curtailing habitat loss, by honestly
> recognizing that humans are now the primary and unstoppable vector for plant
> migration, and by working with that flow.

I find those two paragraphs at odds.  If we are to recognize that
"humans are now the primary and unstoppable vector for plant
migration" and act accordingly, then the hope for allowing
mega-farms to return to "wild land" seems lost as we are the main
force behind these very same farms.  I think the very reason this
is an issue is that people have decided there has to be an
alternative.  I do want to say that I realize food production via
natives is a much more difficult issue.  I mean to comment mainly
on non-food plantings.

> "Natives that are not native" is a nice way to re-frame the whole "natives
> vs exotics" debate. It points up an artificial distinction that disappears
> when we use a broader, and I think more appropriate, scale. As Mollison asks
> in "Travels in Dreams," Native to where? If a sub-species found only on one
> hillside moves to another hill, is that an invasion? Or if it blows to the
> next watershed, or slides in via continental drift? A shift in time-scale
> virtually erases the entire debate. Looking at history, many exotics
> eventually equilibrate with the "native" flora, and many natives disappear
> when climate changes.

Exotic invaders taking over systems due to poor human
decision-making do not equilibrate with natives.  The time scales
you suggest are extremely large not generational.  Most of
current day noxiuos weed programs or native resto efforts deal
with massive generational shifts.  I think this obscures the

> Of course, introducing a plant known to be invasive is foolish unless done
> in the right context. 

Just what is the "right context"?  How can one limit the damage
one does to one's own property?

> But I can't get upset about most invasive plants. They
> are usually branded as invasive because they interfere with humans' use of
> an area, by displacing cattle forage or farmland. Now that's ironic. 

Can you support this?  I don't know of any reasoned rationale
such as this.

> And
> generally--of course there are exceptions--invasive plants are soil- and
> canopy-building pioneers that move into disturbed or mistreated land. Kudzu,
> gorse, and Scotch broom are excellent examples of N-fixing, "wound-healing"
> exotics that are hated because they are working hard to restore cleared land
> to forest. It's this "intermediate" nature of many invasives that's hard for
> us to take--they are neither meadow nor forest, but form scratchy thickets
> between the two in successionary phase.  Ecosystems, particularly unforested
> ones like prairie and wetland, are in constant flux. It's painful for us to
> watch a favorite meadow be swallowed by brush, but that's nature's way.

The problem with Kudzu is not that it restores cleared land to
forest.  It is quite the opposite.  It can handily exploit such
cleared areas but eventually get into forests and turn them into
graveyards.  Kudzu was initially used for two things, cattle
forage and erosion prevention.  It may very well serve those
functions, but it requires a great deal of effort for it not to
become a problem.  That is not "nature's way".

> I think it's humans' inability to think in long time-frames that gives
> invasives a bad name. 

I think it is this same trait that enables us to justify, or at
least feel comfortable with, our poor decision-making.  

> And most relatively undisturbed native ecosystems are
> under no threat from exotics (wetlands may be an exception, but wetland
> invaders like purple loosestrife usually travel up canals and ditches).

This is not supported by fact.  Many relatively undisturbed
systems now have huge invasive exotic problems.  A prime example
is Hawaii.  Hawaii has massive exotic problems in its natural
areas.  The southeast also has severe problems. It doesn't stop
with plants, but includes animals as well. 

> David Holmgren's ideas about recombinant ecologies--hybrid native/exotic
> "weedscapes" that rapidly restore canopies over degraded land--are a great
> example of innovative thinking about this debate (see Permaculture Magazine
> vol 8).

In my mind, this is an example of short term thinking.  It's also
an issue of rehabilitation and not restoration.  A single goal of
"restoring" degraded land being used to champion plants that may
cause problems?  I would hope that folks put more thought into
areas slated for restoration or rehab.  Why do this when other
options are available?  Again, this speaks to rehab/resto and not
food production.  
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