Annette & Scott Ranger
ranger at AMERICA.NET
Wed Jul 30 16:56:44 CDT 1997
I'm surprised no one has suggested The Nature Conservancy - Natural
Heritage Network ranking:
GLOBAL RANKS (denoted by G and number 1 to 5 or a letter code)
G1 Critically imperiled globally because of extreme rarity (typically
less than 6 occurrences, less than 1,000 individuals or very few
remaining acres) or because of some factor(s) making it especially
vulnerable to extinction.
G2 Imperiled globally because of extreme rarity (typically 6-20
occurrences, 1,000-3,000 individuals or few remaining acres) or because
of some factor(s) making it very vulnerable to extinction throughout its
G3 Rare or uncommon (typically 21-100 occurrences or 3,000-10,000
individuals) throughout its range; or found locally, even abundantly, in
a restricted range (e.g., in a single state or physiographic region); or
vulnerable to extinction throughout its range because of specific
G4 Widespread, abundant and apparently secure globally, though it may
be quite rare in parts of its range, especially at the periphery
(typically 101 + occurrences & 10,000 + individuals); some cause for
long-term concern exists.
G5 Demonstrably secure, widespread and abundant globally; although it
may be quite rare in parts of its range, especially at the peripheries.
GH Possibly extinct; of historical occurrence throughout its range,
i.e., formerly part of the established biota; still some hope of
GX Presumed extinct, with virtually no likelihood that it will be
GU Unrankable; possibly in peril, but status is uncertain.
SUBSPECIES RANKS (denoted by T and a number (1 to 5) or letter code)
T1-5 Same ranks as above, but applied after the G rank for subspecific
(trinomial) taxa (e.g., G5T2).
NATIONAL RANKS (denoted by N and a number (1 to 5) or letter code)
N1-5 Same ranks as above, but applied to taxa based only on its
populations or occurrences within the borders of a nation.
NE An exotic species established in the United States
NA Accidental in the United States, part of established biota
STATE RANKS (denoted by S and a number (1 to 5) or letter code)
S1-5 Same ranks as above, but applied to taxa based only on its
populations or occurrences within the borders of a state.
SE An exotic species established in the state
SA Accidental in the state, part of established biota
SR Reported in state
SRF Reported in state, but report was inaccurate (false)
SZ Zero 'occurrences' (unreliably distributed in winter or during
SP Potential; possibly in state, given known distribution in adjacent
MODIFIERS (added to a rank as additional information)
? There is some doubt concerning status (e.g., G2?)
Q Questionable taxonomy (e.g., G4Q)
N Non-breeding (e.g., S1N)
B Breeding (e.g., S1B)
C Captive or cultivated only
Two G, T, N or S rankings together (G2G3, N4N5, T1T2, S3S5, etc.)
indicated uncertainty; the ranks given span the range of uncertainty.
This system has numerous advantages:
1. it is in widespread use in the U.S. by the state Natural Heritage
Programs and many federal agencies (like the U.S. Forest Service), and
by The Nature Conservacy in their international efforts.
2. it attempts in a simple, easy to understand manner, a quantification
3. it addresses all the problems of just where a species is rare. A
plant can be G5S1, meaning it is demonstrably secure in its worldwide
distribution by critically imperiled in a given state
4. it allows for "honesty" in the communication of unsure information.
With all this going for it, why invent something else?
More information about the Taxacom