Your words, "disturbance from the outside designed to produce a
state change," caught my eye. When we introduce prescribed fire
into an ecosystem, this is what we are doing, i.e. introducing
disturbance to produce a state change. Yet, ecosystems regularly
introduce fire on their own, usually via lightning. Is fire a
disturbance from the outside or part of the system? Seems to
depend on perspective, as does what's inside and outside.
-- Jim Saveland /s=j.saveland/ou1=w01c@mhs-fswa.attmail.com