RE: all theory thread DESIGN PRINCIPLES used in our course notes.

[Scott Pittman <pci@permaculture-inst.org>]

I agree with Ava's thoughtful reply and would like to add my
own dilemma regarding native versus non-native plants.

Most of what I grow in the garden for food are European table
vegetables.  What isn't from Europe is originally from Peru (potato)
, Mexico (corn), Africa (okra), Asia (dikon).  My eggs come from
poultry that originated in Asia.  Some medicinals hail from
Siberia.  While I have led the good fight against Russian Olive
(Elaeagnus angustifolia) which is claiming our riparian areas I recently
realized that without the Russian Olive these riparian areas would have
no overstory at all.  Since flooding is no longer allowed to occur
the "native" cottonwoods are no longer germinating and they
were the primary riparian overstory plant in Northern New Mexico. 
Since Russian Olive germinates at the drop of a hat (or the drop of a
bird scat)  it is has very successfully filled this empty niche and
is doing a good job of preventing erosion, providing shade for understory
species, sustaining bird populations, and who knows what other
benefits.  Until we can reintroduce flooding in our riparian zones
it seems that this pioneer is doing an invasively good job.  The
Salsola kala (tumbleweed) from Australia is another pestiferous plant
that pioneers bare soil and holds it in place until it is succeeded by a
more desirable, occasionally, native plant.  The list of non-native
plants is endless and many of them provide a service in niches that would
otherwise deteriorate through erosion.  

A problem I have is looking for broad canopy overstory plants, that fix
nitrogen, in order to mitigate light saturation in the high desert. 
How I long for those tropical legumes to provide light shade for my
field.  My plants suffer through the summer, even with high moisture
content, because of heat and light saturation; photosynthesis stops
around noon so my plants short growing season is further shortened by
inactivity.  The ideal plant would have a high broad canopy, fix
nitrogen, have grey green or silvery foliage to resist ultraviolet,
provide light shade, and be drought tolerant. I finally settled for Honey
Locust (Gleditsia spp.) which is native to the East coast USA, and
central America but not here,  Though Gleditsia provides many of the
functions I am looking for it doesn't satisfy them all.  Robinia
spp. would have given me the nitrogen but suckers too much for a field
crop situation and has a more erect canopy than I want.  What else
is there that provides the multiple functions I am looking for and is
native?, and native to where?  Is the East coast native?; is
southern New Mexico native?  I guess it depends on your definition
and seems to be more bound up with geo-political boundaries than
biomes.

I think that the ecofascism label is often misapplied to people who are
concerned with rampancy and over competition from exotic species
introduction but I have certainly encountered what I would call
ecofascism from those who think that all non-natives are verboten
and their intolerance knows no bounds.  I'm personally not sure
what a native truly is because one has to pick a particular geologic time
to define what is native.  What is desert today and is filled with
drought tolerant "natives" was once a sonorous (Sonoran Desert)
wet climate with a completely different set of "natives"; are
those past natives now exotic to their past home?  Are we talking
about native to place, or climatic situation, or soil types?  

I know it is our responsibility to proceed with caution and lots of
thought and research but ultimately I think we will have to use whatever
is most suitable to our ultimate goal of restoration and creating
sustainable situations in our immediate environment.  Most of us are
looking at remnant environments anyway and don't have a clue what was in
our environment before over grazing, clear cutting, mining, climate
change, increased ultraviolet radiation, and other man created changes
produced what we are looking at today.  Well, we do have some clues
but the total story is still somewhat vague.  Rather than wait in
the indecisive clutch of native versus non-native I think it better to
try and rebuild a healthy functioning ecosystem using the best of the
natives but not being afraid to use analog species for those niches that
are critical for the functioning of the whole.

Scott