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Re: Balance = Steady State

> The hardest things to teach the novice are observation and 
> patience.  I guess the point we need to get across is that our job 
> as aquarists is to manage "dynamic states".  

Bingo.  You said it better than me.

I am changing some of the principles used in natural resource
management to accomodate our aquatic systems.  As a result,
my definition of "steady state" includes the following:

  No (observable) state change over time, as a result of
    (1) natural processes (species and cycles present)
    (2) environmental input.

Resource managers ONLY include (1).  They never do (2).  I
am proposing that our definition needs (2) because the aquarist,
for all practical purposes, IS the environmental input (light,
water movement, nutrients, CO2, etc.)

> At least in my experience, even the best aquarium doesn't remain 
> "steady state" without planned intervention.  [snip]

> While as a whole, I would consider my tank to be "steady state" in 
> that the amount of CO2, trace elements, fish food, water changes 
> etc. remains essentially the same on a day to day basis, and has 
> for several years.  At the same time, there is the constant 
> "tweaking" to keep various species where _I_ decide they should 
> stay.  So from this perspective, the tank is almost continually in 
> a "dynamic state".

You (the aquarist) are simulating foraging or vegetative browsing
by selecting what plant species (and how much) to remove.  The
end result is a system that does not change (observably).  This
is also done in the real world:  livestock grazing (or deer 
browsing) simulates fire, and both selectively remove vegetation.
We don't have large mammals or fire, but we can have the aquarist,
fish, crustaceans, diseases, snails, etc. do the same thing.
Because all human intervention falls under part (2) of my
definition (environmental input), your system would be in steady 
state according to this definition.  

If you had a pond, you could still reach a similar steady state
(but probably not exactly, because you can't manually control
inputs; (2) is defined for you, not by you).  Species present
will balance in densities and foraging characteristics with
the vegetation species distribution present.  We may not like
that distribution, but everything will eventually balance out.

Perhaps another time I will have to explain in detail the
counter-intuitive influences of "geologic time".  :-)

> [snip, WORD and CONCEPT]
> The concept we need to get across to the novice is the _dynamic_ 
> nature of the system.  To really do well with planted tanks, you 
> have to understand _why_ you are making the changes you've decided 
> to make, and what effect those changes have on other parts of the 
> system.

We agree.    ;^>

--charley                            Fort Collins, Colorado USA
charleyb at gr_hp.com	or	charley at agrostis_nrel.colostate.edu