[MPWG] Invasives: terms & definitions

Plant Conservation plant at plantconservation.org
Fri Jul 2 10:20:37 CDT 2004


Hi everyone,

In light of Patricia's recent question of the month post and subsequent
replies, I think it is important to carefully define the terms that we use
so that everyone can have a fruitful discussion using the same language.

As the Medicinal Plant Working Group is part of the Plant Conservation
Alliance, I suggest that we use the definitions used by the Alien Plant
Working Group (also part of PCA).  The following terms/definitions are
taken from the "What the heck is an invasive plant?" brochure which can be
viewed in its entirety at http://www.nps.gov/plants/alien/pubs/whatis.pdf.

Native or Indigenous Species: One that occurs in a particular place
without the help of humans.  As this is not always easy to determine,
species native to North America are generally recognized as thos occuring
on the continent prior to European settlement.

Exotic Species (alien, foreign, non-indigenous, non-native): An organism
is considered exotic when it has been introduced by humans to a
location(s) outside its native or natural range.  This designation applies
to a species introduced from another continent, another ecosystem, and
even another habitat within an ecosystem.

Invasive Species: A species that displays rapid growth and spread,
establishes over large areas, and persists.  Invasiveness is characterized
by robust vegetative growth, high reproductive rate, abundant seed
production, high seed germination rate, and longevity.  Some native plants
exhibit invasive tendencies in certain situations.

Please note that nowhere in those definitions is it said that all exotic
species are invasive species.  I would appreciate it if everyone would
read the whole brochure (it's not very long) so we can have a good
discussion without confusion over the basic terms.

Olivia
SER/PCA
http://www.nps.gov/plants
plant at plantconservation.org





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