The NatureServe conservation status
system was developed by NatureServe
, The Nature Conservancy
(TNC) and the Natural Heritage Network
as a ranking of the relative imperilment of species on global, national and/or regional levels. It is also called TNC ranks
or the NatureServe status
In the system, G codes refer to rankings made at the global level (G-rank), N codes refer to rankings made at a national level (N-rank) and S codes refer to rankings made at the sub-regional level (S-rank), such as states within the US:
- X - presumed extinct (not located despite extensive searches)
- H - possibly extinct [or h historical occurrence (still some hope of discovery)]
- 1 - critically imperilled (typically five or fewer occurrences or 1,000 or fewer individuals)
- 2 - imperilled (typically six to twenty occurrences or 1,000 to 3,000 individuals)
- 3 - vulnerable (rare; typically 21 to 100 occurrences or 3,000 to 10 000 individuals)
- R or ? - Recorded within nation or state, but local status not available; when combined with global rank of G1 to G3, local status is 'Indeterminate'
- 4 - Apparently secure (uncommon but not rare; some cause for long-term concern, usually more than 100 occurrences and 10,000 individuals)
- 5 - Secure (common, widespread and abundant)
Thus, for example, a G3 species is "globally vulnerable", and an N2 species is "nationally imperilled" for whatever country the rank is assigned. Species with G, N, or S rankings of 4 or 5 are generally not the basis for major conservation actions.
Infraspecific taxa (subspecies, varieties and other designations below the level of the species) can also be assigned T-ranks, which is appended to the G-rank.
External link and references