Green-scaled willow (Salix chlorolepis) COSEWIC assessment and status report: chapter 2

COSEWIC Executive Summary

Green-scaled willow
Salix chlorolepis

Species information

Green-scaled willow (Salix chlorolepis) is a branched dwarf shrub, typically under 30 cm tall, with erect branchlets. The simple leaves are short-stalked and are initially covered with a whitish-waxy coating on both surfaces, with the upper surface subsequently turning green; they are up to 25 mm long, entire, egg-shaped, and widest at the apex, becoming hairless with age. The catkin bracts are hairless, olive green in colour and persist through to the maturation of the capsule. The catkins are short-stalked and measure 5 to 13 mm in length. The staminate flowers (on male plants) have two glands near the base. The pistillate flowers (on female plants) have a style with a bifid stigma consisting of two elongate, divergent lobes. The fruit is a short-stalked, hairless capsule 4 mm long.

Distribution

Green-scaled willow occurs exclusively on the alpine-type serpentine outcrops of Mount Albert, Quebec. Given its limited distribution, green-scaled willow is considered to be an endemic species.

Habitat

The species occurs in poorly vegetated habitats on rocky, stabilized slopes of alpine serpentine between pebbles and gravels or on thin dry or moderately moist soils exposed to full sunlight. Historical collections mention the presence of the green-scaled willow in bog areas on the summit plateau. The species’ habitat is strongly associated with elevation, which ranges from 825 m to 1,050 m.

Biology

As in all willows, the species is dioecious, having separate male and female plants. It flowers from early July to mid-August, after leaf development. Fruiting begins in the last of week of July and continues until the first frosts (early September). It is generally insect- and wind-pollinated. This would explain the relatively high frequency of the hybrid (Salix x gaspeensis) between green-scaled willow and short-fruit willow (Salix brachycarpa). The seeds have a tuft of silky hairs that facilitates wind dispersal.

Population sizes and trends

It is estimated that approximately 300 individuals grow on Mount Albert. While most sites generally have only one or two individuals, one site has roughly 200. Not all of the glacial cirques of Mount Albert have been explored, but it is believed that the total number of individuals would probably not exceed 1,000 individuals. A number of botanists have tried, unsuccessfully, to find green-scaled willow. In 1994, the species was found in four glacial cirques in Mount Albert’s Vallée du Diable. In the 2004 inventory, six new sites were discovered on Mount Albert, several outside Vallée du Diable. Approximately 45 hours of fieldwork were carried out on Mount Albert to locate the new sites.

Limiting factors and threats

The most important site for the green-scaled willow population is in the westernmost part of Vallée du Diable where it is adjacent to the International Appalachian trail on Mount Albert. The site is highly exposed to human foot traffic, because some hikers take shortcuts around obstacles thereby coming in contact with the willow. The managers of Gaspésie Provincial Park attempt to reduce such widening of the trail by hikers. All other sites are inaccessible and no human impacts are anticipated.

Hybridization between green-scaled willow and short-fruit willow is frequent on Mount Albert. Although a number of hybrids have been observed, the risk of introgression with short-fruit willow requires further study.

Special significance of the species

Serpentine soils alter both plant appearance and functions. These alterations, combined with the isolation characteristic of serpentine habitats, favour the formation of new species. That is why these environments are generally known for their concentration of endemic species with small ranges. The co-occurrence of serpentine and an alpine-tundra habitat is quite rare in northeastern North America, and the green-scaled willow is the evolutionary result of this type of environment.

Existing protection

NatureServe has assigned the green-scaled willow a rank of critically imperiled at the global, national, and subnational (provincial) level, namely G1, N1, S1. Argus and Pryer consider it rare in Canada and assign it, on the basis of another evaluation system, a Canadian priority rating of 2.

Green-scaled willow is now protected in Quebec under the Act Respecting Threatened or Vulnerable Species and has been designed “threatened” since 1995. At present, the only occurrence of the species is located within a protected area, Gaspésie Provincial Park.

COSEWIC History

The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) was created in 1977 as a result of a recommendation at the Federal-Provincial Wildlife Conference held in 1976. It arose from the need for a single, official, scientifically sound, national listing of wildlife species at risk. In 1978, COSEWIC designated its first species and produced its first list of Canadian species at risk. Species designated at meetings of the full committee are added to the list. On June 5th 2003, the Species at Risk Act (SARA) was proclaimed. SARA establishes COSEWIC as an advisory body ensuring that species will continue to be assessed under a rigorous and independent scientific process.

COSEWIC Mandate

The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) assesses the national status of wild species, subspecies, varieties, or other designatable units that are considered to be at risk in Canada. Designations are made on native species for the following taxonomic groups: mammals, birds, reptiles, amphibians, fishes, arthropods, molluscs, vascular plants, mosses, and lichens.

COSEWIC Membership

COSEWIC comprises members from each provincial and territorial government wildlife agency, four federal entities (Canadian Wildlife Service, Parks Canada Agency, Department of Fisheries and Oceans, and the Federal Biodiversity Information Partnership, chaired by the Canadian Museum of Nature), three non-government science members and the co-chairs of the species specialist subcommittees and the Aboriginal Traditional Knowledge subcommittee. The Committee meets to consider status reports on candidate species.

Definitions (2006)

Wildlife Species
A species, subspecies, variety, or geographically or genetically distinct population of animal, plant or other organism, other than a bacterium or virus, that is wild by nature and is either native to Canada or has extended its range into Canada without human intervention and has been present in Canada for at least 50 years.

Extinct (X)
A wildlife species that no longer exists.

Extirpated (XT)
A wildlife species no longer existing in the wild in Canada, but occurring elsewhere.

Endangered (E)
A wildlife species facing imminent extirpation or extinction.

Threatened (T)
A wildlife species likely to become endangered if limiting factors are not reversed.

Special Concern (SC)Footnotea
A wildlife species that may become a threatened or an endangered species because of a combination of biological characteristics and identified threats.

Not at Risk (NAR)Footnoteb
A wildlife species that has been evaluated and found to be not at risk of extinction given the current circumstances.

Data Deficient (DD)Footnotec
A category that applies when 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.

 

Canadian Wildlife Service

The Canadian Wildlife Service, Environment Canada, provides full administrative and financial support to the COSEWIC Secretariat.

 

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