Rarity Ranking Definitions

Where available, rarity rankings for each species are drawn from four sources:
• Harms’ Ranking System (2003)
• Nature Conservancy of Canada/Saskatchewan Conservation Data Centre
• Species at Risk in Saskatchewan (Endangered Species Advisory Committee)
• Committee on the Status of Endangered Wildlife in Canada (COSEWIC)

See below for ranking definitions and descriptions.

Harms' Ranking System
Harms’ Ranking System is based on Vern Harms Checklist of the Vascular Plants of Saskatchewan and the Provincially and Nationally Rare Native Plants in Saskatchewan (Extension Division, University of Saskatchewan, 2003).

Vern Harms is a well-known Canadian taxonomist whose opinion is highly regarded in the botanical community. He is an Emeritus Professor in the Department of Biology at the University of Saskatchewan and a former curator of the SASK Herbarium. The rarity of plant species are ranked according to the following definitions:

EXT? (Extirpated):Species that have been previously recorded in the province but apparently no longer exist here.

END (Endangered): Species that are critically threatened by human or natural processes throughout their entire range in Saskatchewan. There are generally fewer than five known sites in the province, and the plants are locally sparse at each site.

THR (Threatened): Species that are imperiled by their rarity and are likely to become provincially endangered. There are between 6 and 15 localities of these species in Saskatchewan and plants are locally sparse at most of them.

VUL (Vulnerable): Species that are at risk of because of low or declining numbers. There is no immediate endangerment to these species. There are generally between 16 and 25 known sites in Saskatchewan.

Nature Conservancy of Canada (national ranking)
Saskachewan Conservation Data Centre (provincial ranking)

The Nature Conservancy of Canada is a non-profit organization dedicated to the protection of biodiversity in Canada. Founded over 40 years ago, the Nature Conservancy acquires ecologically significant land through purchase, donation, or conservation easement to protect plant and animal species by preserving intact landscapes. Since 1962, the Nature Conservancy has protected over 1.9 million acres of land.

The Saskatchewan Conservation Data Centre, which was formed as a co-operative venture between Saskatchewan Environment and the Nature Conservancy of Canada, is now a partnership between Saskatchewan Environment and Nature Saskatchewan. Their mission is to gather, interpret, and distribute standardized information on the status of wild species and their communities.

The Nature Conservancy/Saskatchewan Conservation Data Centre ranking definitions are provided below.

Example: G5 N4 S2

G: Global
N: National
S: Provincial
T: Infraspecific taxa (subspecies or variety) rank
X: The species has been extirpated from a region or is extinct.
H: Only historical records of the species exists in the area and there has been no recent verification.

1: The species is critically imperiled because of extreme rarity or some factor of its biology or environment that makes it vulnerable to extirpation or extinction. There are five or fewer occurrences, or very few remaining specimens (fewer than 1,000 plants).

2: The species is imperiled because of rarity or some factor of its biology or environment that makes it vulnerable to extirpation or extinction. There are between 6 and 20 occurrences, or few remaining specimens (1,000 to 3,000 plants).

3: The species is vulnerable because it is very rare and local throughout its range, is found only within a restricted range, or is threatened by some factor of its biology or environment. When found within a restricted range, the plant may be abundant in some locations. It is generally rare to uncommon, with between 21 and 100 occurrences or between 3,000 and 10,000 plants.

4: The species is apparently secure. It may be rare in parts of its range—for example, the periphery—but is generally common and widespread. Although there is no cause for immediate concern, there is a possibility for long term concern. There are more than 100 occurrences and more than 10,000 plants.

5: The species is demonstrably secure because it is widespread and abundant. It may be rare in parts of its range but in general is very common. There are well over 100 occurrences and far more than 10,000 plants.

?: The species is unranked at that particular level.

Q: The taxonomy of the species is questionable and must be resolved before the species can be ranked.

U: The species is unrankable because of a lack of information or conflicting reports.

Species at Risk in Saskatchewan (SaR)
The Saskatchewan Species at Risk (SaR) rankings are established by the provincial Endangered Species Advisory Committee (ESAC). The committee, which is comprised of representatives from 12 stakeholder groups, reviews status assessments and advises the provincial government on the conservation and protection of wild species at risk in Saskatchewan.

• EXT (Extirpated): The species does not exist in the wild in Saskatchewan but occurs outside the province.
• END (Endangered): The species is threatened with immediate extirpation or extinction.
• THR (Threatened): The species is likely to become endangered if the limiting factors are not reversed.
• VUL (Vulnerable): The species is of special concern because of low or declining numbers caused by human activities or natural events.

Committee on the Status of Endangered Wildlife in Canada (COSEWIC) (national ranking)
The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) determines the national status of Canadian species, subspecies, and varieties of plants and animals that may be at risk of extinction or extirpation. The knowledge used to assign rankings is based on science as well as Aboriginal and community knowledge. The evaluation process of each species is independent and transparent. The Species at Risk Act (SARA) established in 2003 designated COSEWIC as an advisory body.

COSEWIC ranking definitions:


REP (Report): A report has been or is being prepared and the ranking is pending.

EXT? (Extirpated): The species has been previously recorded but apparently has been extirpated from Canada.

END (Endangered): The species is critically threatened and is in immediate danger of extirpation throughout its range in Canada. Extreme rarity of the species is primarily attributed to human activity.

THR (Threatened): The species is imperiled because of its rarity and is likely to become endangered in Canada if the factors causing its decline are not reversed.

SPC (Special Concern): The species is at risk because of low or declining numbers but faces no obvious or immediate threats.

DD (Data Deficient): The available information is insufficient (a) to resolve a species' eligibility for assessment or (b) to permit an assessment of the species' risk of extinction.