Conservation Status Ranks

State and Global Ranks

This ranking system facilitates a quick assessment of a species’ or habitat type’s rarity and is the primary tool used to develop conservation, protection, and restoration priorities for individual species and natural habitat types. Each species or habitat is assigned both a state (S) and global (G) rank on a scale of critically imperiled (1) to secure (5). Factors such as range extent, the number of occurrences, intensity of threats, etc., contribute to the assignment of state and global ranks. The definitions for state and global ranks are comparable but applied at different geographic scales; something that is state imperiled may be globally secure.

The information supporting these ranks is developed and maintained by the Maine Natural Areas Program (state ranks) and NatureServe (global ranks).

Rank Definition
S1 / G1 Critically Imperiled – At very high risk of extinction or elimination due to very restricted range, very few populations or occurrences, very steep declines, very severe threats, or other factors.
S2 / G2 Imperiled – At high risk of extinction or elimination due to restricted range, few populations or occurrences, steep declines, severe threats, or other factors.
S3 / G3 Vulnerable – At moderate risk of extinction or elimination due to a fairly restricted range, relatively few populations or occurrences, recent and widespread declines, threats, or other factors.
S4 / G4 Apparently Secure – At fairly low risk of extinction or elimination due to an extensive range and/or many populations or occurrences, but with possible cause for some concern as a result of local recent declines, threats, or other factors.
S5 / G5 Secure – At very low risk or extinction or elimination due to a very extensive range, abundant populations or occurrences, and little to no concern from declines or threats.
SX / GX Presumed Extinct – Not located despite intensive searches and virtually no likelihood of rediscovery.
SH / GH Possibly Extinct – Known from only historical occurrences but still some hope of rediscovery.
S#S# / G#G# Range Rank – A numeric range rank (e.g., S2S3 or S1S3) is used to indicate any range of uncertainty about the status of the species or ecosystem.
SU / GU Unrankable – Currently unrankable due to lack of information or due to substantially conflicting information about status or trends.
SNR / GNR Unranked – lobal or subnational conservation status not yet assessed
SNA / GNA Not Applicable – A conservation status rank is not applicable because the species or ecosystem is not a suitable target for conservation activities (e.g., non-native species or ecosystems.
Qualifier Definition
S#? / G#? Inexact Numberic Rank – Denotes inexact numeric rank.
Q Questionable taxonomy that may reduce conservation priority – Distinctiveness of this entity as a taxon or ecosystem type at the current level is questionable. The "Q" modifier is only used at the global level.
T# Infraspecific Taxon (trinomial) – The status of infraspecific taxa (subspecies or varieties) are indicated by a "T-rank" following the species' global rank.

State Legal Status

State legal status is defined according to Title 12 Section 544, and Title 12 Section 544 B which mandate the Department of Agriculture, Conservation and Forestry to produce and biennially update the official list of Maine's Endangered and Threatened plants. Periodic changes to the list are recommended to the Department by a technical advisory committee of botanists who use the most recent population data as per the Maine Natural Area Program's database, along with other relevant research and taxonomic information to recommend status changes.

  • E–Endangered: Rare and in danger of being lost from the state in the foreseeable future; or federally listed as Endangered.
  • T–Threatened: Rare and, with further decline, could become endangered; or federally listed as Threatened.

Non-Legal status

  • SC–Special Concern: Rare in Maine, based on available information, but not sufficiently rare to be considered Threatened or Endangered.
  • PE–Potentially Extirpated: Species has not been documented in Maine in past 20 years or loss of last known occurrence has been documented.

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