I'm sure someone has already done this thinking and if so, please direct me 
towards it

When is an invasive no longer an invasive?

Presumably once the effect of an invasion is no longer "measurable" then one 
might say that the invader is no longer an invader but a resident.  I can 
envision a variety of levels of invasion.

1. effect is minimal and the invasion is unsuccessful, the invader doesn't 
stick around

2. effect is measurable but not substantial, the invader nudges its way into 
the new ecosystem, everyone moves over and are effected (more competition for 
resources, carrying capacity may be reduced, etc.).  The effect is measurable 
for a period of time, but then doesn't change...becomes stable.

3. effect is measurable and substantial, the invader bullies its way into the 
new ecosystem, everyone moves over, some get hit especially hard.  The effect 
is measurable for a period of time, but then doesn't change...becomes stable.

The 3 levels is a simplistic accounting for all that happens out there, but 
works as a general starting point, at least for me.

Thoughts?

Lui

Lui Marinelli, PhD
VP Contract Administration, SCFA
Instructor, School of Renewable Resources
Selkirk College
301 Frank Beinder Way
Castlegar, BC
V1N 3J1
CANADA

(250) 365-1269
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