Green-scaled willow (Salix chlorolepis) COSEWIC assessment and status report: chapter 5

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Habitat

Habitat requirements

Green-scaled willow occurs in poorly vegetated habitats on the rocky stabilized slopes of alpine-type serpentine between pebbles and gravel or in thin dry or moderately moist soils exposed to full sunlight (Lavoie and Fleurbec, 1995; Coursol, 2001). Several specimens were found in 2004 on slightly emergent serpentine boulders in the middle of an intermittent stream. Historical collections indicate the presence of the green-scaled willow in bog areas on the plateau of the summit (Lavoie and Fleurbec, 1995), but no individuals have been located despite several kilometres of transects on the plateau in 2004 (Figures 5). The habitat of the green-scaled willow is strongly associated with elevation, which ranges from 825 m and 1,050 m, with a strong concentration of individuals between 925 and 950 m (Figures 5 and figure6).

Mountain holly-fern (Polystichum scopulinum) and serpentine stitchwort (Minuartia marcescens) are two species considered threatened in Quebec (Act Respecting Threatened or Vulnerable Species) that sometimes share the same habitat as the green-scaled willow on Mount Albert. A number of species likely to be designated threatened or vulnerable in Quebec (Tardif et al.2005), such as Aleutian maidenhair (Adiantum aleuticum), Indian’s dream (Aspidotis densa), swamp thistle (Cirsium muticum var.monticolum), rough fescue (Festuca altaica) and dwarf Arctic groundsel (Solidago simplex subsp. simplex var. chlorolepis), also share the habitat of the green-scaled willow.

Habitat trends

The green-scaled willow is protected throughout its range. In Quebec, all sites of the Mount Albert population are located in Gaspésie Provincial Park. This section of the park is designated a “maximum preservation zone”. No human activity is authorized, except for hiking on two trails. The most significant disturbances are limited to the trampling of individuals that occur alongside the International Appalachian Trail on Mount Albert. No other long-term threats are anticipated, unless off-trail downhill skiing becomes developed in other sectors of Mount Albert; in this case the significance of disturbances that could be caused to green-scaled willow habitat by avalanches would have to be studied, but these appear to be low to nil.

A number of alpine serpenticolous species, such as the serpentine stitchwort, occur on Mont du Sud, which is located 12 km southwest of Mount Albert in Gaspésie Provincial Park. A brief site visit in 2004 had been planned on the basis of preliminary reports of the Quebec Natural Heritage Data Centre (CDPNQ) indicating a low surface area of serpentine (300 m long), but the potential area is at least 1.5 km long. A number of short-fruit willow specimens were observed at the top of a talus slope at an altitude of 650 m, which is much lower than the populations of Mount Albert. Given the length of the visit in 2004, no green-scaled willows were found, but the site has very high potential, despite an elevation of approximately 800 m (Figure 5).

A number of serpenticolous species also occur on Mount Olivine, which is also located in Gaspésie Provincial Park, 2 km east of Mount Albert. However, a visit to the mountain in 2002 did not turn up any specimens of green-scaled willow (Figure 5). The site measures 1.7 km long by 600 m wide on the summit and east side of the mountain. It is unlikely that green-scaled willow occur at the site because it is located at an elevation of approximately 670 m and the mountainside is less exposed to the prevailing winds.

Habitat protection/ownership

The Quebec site is currently located within a protected area: Gaspésie Provincial Park.