APPENDIX 1. Global 

 and State Rank 

 Guidelines 



For state ranks, substitute S for G in these defini- 

 tions 



G 1 = Critically imperiled globally because of 

 extreme rarity (typically five or fewer 

 occurrences or very few remaining acres) 

 or because of some factor(s) making it 

 extremely vulnerable to exptirpation. 



G2 = Imperiled globally because of extreme 

 rarity (typically six to 20 occurrences or 

 few remaining acres) or because of some 

 factor(s) making it very vulnerable to 

 extirpation. 



G3 = Vulnerable; either very rare and local 



throughout its range or found locally (even 

 abundantly at some of its locations) in a 

 restricted range (e.g. a single Great Plains 

 state, a single physiographic or 

 ecoregional unit) or because of other 

 factors making it vulnerable to extirpation 

 throughout it's range. 



G4 = Apparently Secure; Uncommon, but not 

 rare (although it may be quite rare in parts 

 of its range, especially at the periphery). 

 Apparently not vulnerable in most of its 

 range. 



G5 = Secure; Common, widespread, and 



abundant (though it may be quite rare in 

 parts of its range, especially at the periph- 

 ery). Not vulnerable in most of its range. 



GU = Unrankable; Status cannot be determined 

 at this time. 



G? = Unranked; Status has not yet been as- 

 sessed. 



**Modifiers and Rank Ranges** 



? A question mark added to a rank ex- 



presses an uncertainty about the rank in 

 the range of 1 either way on the 1 -5 scale. 



G#G# Greater uncertainty about a rank is ex- 

 pressed by indicating the fioll range of 

 ranks which may be appropriate. 



Q A "Q" added to a rank denotes question- 

 able taxonomy. It modifies the degree of 

 imperilment and is only used in cases 

 where the type would have a less imper- 

 iled rank if it were not recognized as a 

 valid name (i.e. if it were combined with a 

 more common type). 



CRITERIA USED FOR RANKING 



The criteria for ranking are based on a set of 

 quantitative and qualitative factors. These factors 

 are listed below in order of their general impor- 

 tance: 



a. Number of Element Occurrences 

 (EOs); 



the estimated number of EOs 

 throughout the Element's global 

 range; 



b. Abundance: 



the estimated global abundance of 

 the Element (measured by number 

 of individuals, or area, or stream 

 length covered); 



c. Size of Range: 



the estimated size of the Element's 

 global range; 



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