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Re: Native vs non-native.... all theory thread DESIGN PRINCIPLES




Judith Hanna wrote:
>  Scott wrote (replying to Ava and me):
> >" 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."

> That seems a good statement of the balance of responsibility needed -- a
> balance affected by the the degree to which a functioning indigenous
> ecosystem is either still there, or can be recreated. It particularly means
> that, in introducing new species, a responsibility for not bringing in new
> species that will increase the existing threats to communities of native
> species. 

This is well said.  One of the problems however is that in our
attempt to "cover all the bases" with regard to determining
threats/invasiveness/etc. we overlook or fail to notice problems
we might have seen, or, in many cases, we just don't know.

<snip>
> -- What impacts might that species have? These would include
> # allopathies (inhibiting growth of other plants -- which may in some
> situations be a useful effect)
> # tendency to spread (invasiveness)
> # and others that don't occur to me at the moment...

Your checklist is a good start, but in the last part I quoted
above, the last sentence is especially pertinent.  Many
well-meaning scientists have studied organisms ad nauseum before
using them outside of their range, only to create large problems
because you can't predict what may happen when it exploits its
niche in a new habitat.

> The 'minimum maintenance' principle needs to be balanced against a
> precautionary effect here -- if a plant can be kept in check by diligent
> pruning/weeding, then when that work ceases, it spreads.

This is also a very good example of a continuing problem with
humans and plant assumptions.

> If you're gardening within an urban area, completely surrounded by
> buildings and other man-made gardens, then even invasive exotics aren't
> likely to get far -- and pretty well anything growing will be a benefit.

Don't bet on it.  I work in a mainly urban structure and they can
spread quickly...especially in this area where the shredded bark
mulch culture predominates! <grin>

> But what will most help native birds and insect life to survive in the
> urban area will be the plants they're adapted to and in balance with. (In
> the UK, city gardens support more birdlife than monoculture farmland). 

I agree with the first sentence but would like to see the data on
the second.  Here in Louisville, Kentucky (and many other eastern
US cities), the urban birdlife is predominantly non-native...
European Starlings, House Sparrows, Pigeons...er...Rock Doves,
House Finches, etc.  It is true however that most gardening here
is different than that I've seen in Europe.

> If you settle, as many permies do, in a smallholding out in the wilderness
> to commune with nature -- then of course you're taking on a greater
> responsibility and can be expected to look after the local character of
> your local wilderness, and avoid endangering it by unwise introductions.

What happens when you're gone?  I have yet to locate onto a
parcel yet but plan to soon.  I struggle with this one.
-- 
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