Hi Tim and list;
Quick remark as this is my main field (not to imply that I have a right
answer, just keen interest) - so I'll try to add some background
This is a common problem in ecology, however it is actually a problem of
scale, as implied in the questions about when something can be
considered "native." It is difficult to get such precise concepts in
ecology that one can say they are A or B, as in the idealized
experiments in physics. We've discussed around this idea before, but if
one reduces to a different kind of idealism, more appropriate
distinctions might be made, such as formal systems and natural systems,
"Native" refers to long-term presence, which is relative to the
adaptation time of the invader and other organisms. It has some
historical baggage in the idea of climax communities and equilibrium in
ecology, both of which are not being questioned much like Newtonian
mechanics had to yield to a more precise theory in physics. But in the
case of ecology the new ideas are more complex, not more precise. Now we
think of dynamics in a landscape mosaic with no equilibrium state; yet
various kinds of dynamic stability do emerge, like stable limit cycles,
perhaps attractor modes if one analyses that way, etc. Still, it is
possible to talk in relative terms about whether a new organism has had
time to build stable interactions or is acting like a bull in a china
shop. Discord in nature is ultimately costly and it seems that some sort
of "agreement" develops between species to divide up resources, time,
space, etc. It takes time to form those agreements. Its not unlike
someone moving into a new town with a tight social order. There is an
unquantifiable time after which you are no longer a newcommer, and it is
an agreement among neighbors.
For humans to decide nativeness requires no small degree of speculation.
So I agree with the sentiment expressed here in that regard - who's to
say that a species movement isn't "natural?" After all, there was the
mammalian radiation across the land bridge of Panama, human migration
across the bering streight, etc. Perhaps several generations are enough
to erase the memory, but effects can still be discussed many generations
hence.
However, the issue of Fish & WS management is quite a bit more involved.
I too find it amusing to see supposedly objective scientific
justification for management action when in truth it is a value
judgement. The science is there, saying that invasives can wreak havoc
on existing systems and produce rapid changes that we may not find
desirable - but there it is again; our desires. Who's to say rapid
change, perhaps even change killing a million people, is bad? Perhaps
some of those people, but not the ones who end up thriving on the
change. Ecology is dynamic.
Ecological restoration has a problem establishing the goals of
restoration. The current ideal is to do that through community consensus
(a partial myth) or some reasonable process for reaching a "fair"
balance of values. Some like migratory birds and they are used to them,
so manage to keep them. Others like the carp. What does nature like?
Mostly nature likes whatever it ends up doing.
Still, I come to the conclusion for myself that ecosystem management is
very important. Not because we can define what the proper state of
things should be, but because we can predict that extremely rapid change
will be harmful to us and probably many other species. It is the rate of
change that is the issue here, not the quality of it. Human pressure is
changing our ecologies at an unprecedented and accellerating rate. We
currently rival the largest natural extinction event in geologic history
for the numbers of all taxa. We're even threatening our traditional food
supply. So the principle of preservation may be too simple an idea, but
it is really a simplification of the precautionary principle, which is
that the first priority should be to do no unnecessary harm. Balancing
that for all nature is like discussing the common good of the people in
political circles. But just because we can prove that there isn't an
objective answer, doesn't mean the problem is small or that we can
escape it.
Here, again, I find Rosen's approach refreshing because it can help
model the interplay between values and their material results. The idea
of no single largest model, is analogous, or identical, to saying there
is no single right answer. But we don't give up, we invent a new way of
thinking about the problem. Although we might say some terms like
"native" is not a "real physical property" (implying that we give value
to physical properties); it is also possible to enter into a thought
system where all properaties, physical or otherwise, are equally "real"
with regard to understanding our experience (the goal of science) and
managing our experience (the goal of management).
In today's ecological economics parlance some degree of tangibility has
been added by talking about ecosystem "goods and services." Long
discussions are possible on those terms as well, but it pegs the problem
to what humans want and perceive rather than seeking some universal
value system. That has also been attempted. HT Odum was almost religious
about natural "emergy" - a calculation he invented and attached great
"natural value" to. Others seemed to agree that all values we can know
are human values. I can argue either side. I tend to think it is again a
matter of scale. On immediate practical and decision making scales we
use our best judgement of what is good. That is based mostly on
experience and some science. Anyone who proposes a universal value is
probably doomed to failure; however, a means of working with the
complexity of human values may turn out to be a good enough complex
model for nature that a good social process might adequately reflect
natural values (or perhaps create them).
- J Kineman