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Status and Ranking System used by the Natural Heritage Network

This document defines the terms used by Natural Heritage Methodology, including values for status and rank that are used throughout this web site. Click on the links in the following table to view the appropriate section.
 

Federal Status A description of Federal Status which is assigned by the U. S. Fish and Wildlife Service.

State Status A description of State Status values used by the Washington Natural Heritage Program and the Department of Fish and Wildlife.

Global Rank A description of the values used for Global Rank.

State Rank A description of the values used for State Rank.

Element Occurrence An explanation of what constitutes an Element Occurrence.

Federal Status definitions (as defined by USFWS):

LE = Listed Endangered: Any taxon that is in danger of extinction throughout all or a significant portion of its range and that has been formally listed as such in the Federal Register under the Federal Endangered Species Act.

LT = Listed Threatened: Any taxon that is likely to become endangered within the foreseeable future throughout all or a significant portion of its range and that has been formally listed as such in the Federal Register under the Federal Endangered Species Act.

PE = Proposed Endangered: Any taxon that is in danger of extinction throughout all or a significant portion of its range and that has been proposed for listing as such in the Federal Register under the Federal Endangered Species Act.

PT = Proposed Threatened: Any taxon that is likely to become endangered within the foreseeable future throughout all or a significant portion of its range and that has been proposed for listing as such in the Federal Register under the Federal Endangered Species Act.

C = Candidate species: A taxon for which current information indicates the probable appropriateness of listing as Endangered or Threatened and that has been published in the Federal Register as a candidate for listing under the Federal Endangered Species Act.

SC = Species of Concern: A taxon whose conservation standing is of concern but for which status information is still needed. Species of concern lists are not published in the Federal Register.

NL = Not Listed: Used for animal populations or subspecies within a taxon that are not federally listed, when other populations or subspecies of that same taxon are listed.


State Status definitions:

E = Endangered: Any taxon in danger of becoming extinct or extirpated from Washington within the foreseeable future if factors contributing to its decline continue. Populations of these taxa are at critically low levels or their habitats have been degraded or depleted to a significant degree.

T = Threatened: Any taxon likely to become Endangered in Washington within the foreseeable future if factors contributing to its population decline or habitat degradation or loss continue.

S = Sensitive: Any taxon that is vulnerable or declining and could become Endangered or Threatened in the state without active management or removal of threats.

C = Candidate: An animal taxon under review for listing.

M = Monitor: An animal taxon of potential concern.

NL = Not Listed: Used for animal populations or subspecies within a taxon that have no state status, when other populations or subspecies within that same taxon are listed.

X = Possibly Extinct or Extirpated from Washington: Based on recent field searches, a number of plant taxa are considered to be possibly extinct or extirpated from Washington. Taxa in this group are all high priorities for field investigations. If found, they will be assigned one of the above status categories.

R = Review: Plant taxon of potential concern, but for which no status has yet been assigned.
Group 1 (i.e. R1) = Taxon in need of additional field work before a status can be assigned.
Group 2 (i.e. R2) = Taxon with unresolved taxonomic questions.

W = Watch: Plant taxon that is more abundant and/or less threatened in Washington than previously assumed.

P = Priority: At this time, there is insufficient information to assign a statewide status to the non-vascular plant taxa. For now, the lichen and macrofungi lists have been divided into two priority groups (P1 and P2) based on criteria of occurrence pattern, vulnerability, threats, degree of protection, and taxonomy.


State Rank

State rank characterizes the relative rarity or endangerment within the state of Washington. Factors including, but not limited to, number of known occurrences are considered when assigning a rank. Two codes together represent an inexact range (e.g., S1S2) or different ranks for breeding and non-breeding populations (e.g., S1B, S3N).Values and their definitions:

S1 = Critically imperiled in the state because of extreme rarity or other factors making it especially vulnerable to extirpation from the state. (Typically 5 or fewer occurrences or very few remaining individuals or acres)

S2 = Imperiled in the state because of rarity or other factors making it very vulnerable to extirpation from the state. (Typically 6 to 20 occurrences or few remaining individuals or acres)

S3 = Rare or uncommon in the state. (Typically 21 to 100 occurrences)

S4 = Widespread, abundant, and apparently secure in state, with many occurrences, but the taxon is of long-term concern. (Usually more than 100 occurrences)

S5 = Demonstrably widespread, abundant, and secure in the state; believed to be ineradicable under present conditions.

SA = Accidental in the state.

SE = An exotic species that has become established in the state.

SH = Historical occurrences only are known, perhaps not verified in the past 20 years, but the taxon is suspected to still exist in the state.

SNR or S? = Not yet ranked. Sufficient time and effort have not yet been devoted to ranking of this taxon.

SP = Potential for occurrence of the the taxon in the state but no occurrences have been documented.

SR = Reported in the state but without persuasive documentation which would provide a basis for either accepting or rejecting the report (e.g., misidentified specimen).

SRF = Reported falsely in the state but the error persists in the literature.

SU = Unrankable. Possibly in peril in the state, but status is uncertain. More information is need.

SX = Believed to be extirpated from the state with little likelihood that it will be rediscovered.

SZ = Not of conservation concern in the state.

Qualifiers are sometimes used in conjunction with the State Ranks described above:

B - Rank of the breeding population in the state.
N - Rank of the non-breeding population in the state.
B and N qualifiers are used to indicate breeding and non-breeding rank of migrant species whose non-breeding rank may be quite different from their breeding rank in the state (e.g., S1B, S4N for a very rare breeder that is a common winter resident).
? qualifier is used with numeric ranks to denote uncertainty; more information may be needed to assign a rank with certainty. The '?' qualifies the character it follows (e.g., SE? denotes uncertainty of exotic status).
SnSn Two codes (i.e., S1S2) are used to indicate a range of ranks.


Global Rank

Global rank characterizes the relative rarity or endangerment of the element world-wide. Factors including, but not limited to, number of occurrences are considered when assigning a rank.Values and their definitions:

G1 = Critically imperiled globally because of extreme rarity or because of some factor(s) making it especially vulnerable to extinction. (Typically 5 or fewer occurrences or very few remaining individuals or acres).

G2 = Imperiled globally because of rarity or because of some factor(s) making it very vulnerable to extinction throughout its range. (6 to 20 occurrences or few remaining individuals or acres).

G3 = 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 western state, a physiographic region in the East) or because of other factors making it vulnerable to extinction throughout its range. (21 to 100 occurrences)

G4 = Widespread, abundant, and apparently secure globally, though it may be quite rare in parts of its range, especially at the periphery. Thus, the Element is of long-term concern. (Usually more than 100 occurrences)

G5 = Demonstrably widespread, abundant, and secure globally, though it may be quite rare in parts of its range, especially at the periphery.

GH = Historical occurrences only are known, perhaps not verified in the past 20 years, but the taxon is suspected to still exist somewhere in its former range.

GNR or G? = Not yet ranked. Sufficient time and effort have not yet been devoted to ranking of this taxon.

GU = Unrankable. Possibly in peril range-wide but status uncertain. More information is needed.

GX = Believed to be extinct and there is little likelihood that it will be rediscovered.

Qualifiers are used in conjunction with the Global Ranks described above:

Tn Where n is a number or letter similar to those for Gn ranks, above, but indicating subspecies or variety rank. For example, G3TH indicates a species that is ranked G3 with this subspecies ranked as historic.
Q = Questionable. Taxonomic status is questionable and the numeric rank may change with taxonomy.
? = The specified rank is uncertain; more information may be needed to assign a rank with certainty.
GnGn Two codes (i.e., G1G2) are used to indicate a range of ranks.


Element Occurrences

An Element Occurrence is a particular, on-the-ground observation of a rare species or ecosystem. The Element Occurrence is the basic unit of the WNHP inventory but what constitutes an Element Occurrence varies by Element or Element type.

Element Occurrence criteria for rare plant species

For rare plant species, an Element Occurrence is generally defined as a "population." However, even the instance of a single plant is important and will be tracked as an Element Occurrence. On the other hand, high-quality wetland ecosystems and terrestrial ecosystems must meet minimum size and condition standards to be considered an Element Occurrence.

Element Occurrence criteria for high-quality wetland ecosystems

The WNHP does not maintain a comprehensive inventory of all wetlands in the state. The database includes information only on those areas that have been surveyed by program scientists and found to be relatively undisturbed high-quality wetlands. For wetlands included in the database, the physical characteristics, biota, ecosystem functions, processes and settings are essentially natural. For example, to be included in the WNHP database, a freshwater wetland site must meet these six criteria:

1. Contains a native wetland ecosystem type (Element) considered important for preservation within the state.

2. Little or no human-caused changes to wetland topography or soils.

3. No human caused changes to hydrology of the wetland, or the wetland appears to have recovered from any changes.

4. Few or no exotic plant species.

5. Little human-caused disturbance of native vegetation, or vegetation has recovered from past disturbance.

6. No major water quality problems.

Element Occurrence criteria for high-quality terrestrial ecosystems.

Occurrences of terrestrial ecosystem types are determined by the characteristics of each individual ecosystem type. Ecological quality refers to both the ecological condition and the ecological viability of a particular community.

Condition is determined by relative importance of native versus non-native species, extent and nature of human-caused disturbance, and how well the occurrence represents the ecosystem type definition. Viability is determined by size of the area and landscape setting.
Minimum criteria for an occurrence of a terrestrial ecosystem:1. Native plants dominate the site: tree layers composed of only native species.

2. Little or insignificant disturbance to vegetation by logging, conversion to agriculture, heavy grazing, residential development, or other recent human extractive activities that alter the ecosystem processes.

3. Large enough for minimal viability and ecological function: at least 100 acres for forests in the montane provinces and at least four average tree heights wide at its narrowest width, at least 20 acres for forest in the Puget Lowlands, and at least 10 acres for native grasslands.

The degree to which these criteria are applied to a site depends on characteristics of the particular ecosystem types present. Some ecosystem types are found almost exclusively as small patches, perhaps in areas smaller than in criterion 3. In this case, meeting criteria 1 and 2 would be sufficient. Large but moderately disturbed ecosystems representative of types that have been altered throughout their range because of various land uses may need only meet criteria 1 and 3.


Washington Natural Heritage Program - www.dnr.wa.gov/ResearchScience/Topics/NaturalHeritage/Pages/amp_nh.aspx
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Washington Dept. of Natural Resources, PO Box 47014, Olympia, WA 98504-7014