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  • From: Toby Hemenway <hemenway@jeffnet.org>
  • To: permaculture <permaculture@franklin.oit.unc.edu>
  • Subject: Re: all theory thread DESIGN PRINCIPLES used in our course notes.
  • Date: Tue, 29 Aug 2000 08:20:25 -0600


on 8/28/00 Ava Devenport wrote:

> within permaculture design principles and
> *intelligent application of the broad principles*, how would you define
> which plants to cultivate when the natives are/may be NOT native at al
[snip]
> many of our food crops are not native
> to this country at all

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.

"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.

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

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

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).

(just as an aside: does anyone know of a positive effect of the tamarisk
trees (Tamarix spp.) that have taken over large riparian zones in the US
southwest? I don't know the region well enough to see what's going on
there.)

Toby







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