Mountain holly fern (Polystichum scopulinum) COSEWIC assessment and status report: chapter 8

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Limiting Factors and Threats

The most direct threats to P. scopulinum in British Columbia, at the present time, are mining exploration, forest/mining road construction or forest fires. All ultramafic geologic formations have potential for the presence of precious metals. This is evident in that all such outcrops have established mineral claims. The Bright Star Ventures (BSV) Message Board web site (week of Aug 20th to Aug 24th, 2001), accessed 1 Feb. 2005, indicated that they were planning a major exploration program at their recently acquired Platinum and Palladium property within the Tulameen Ultramafic Complex west of Princeton, BC. Over 20,000 ounces of placer gold and platinum have been recovered from this area. Other minerals in the area include copper, nickel, and silver. Properties of BSV include about 560 ha (1400 acres) on Grasshopper Mountain and 1760 ha (4,400 acres) on Olivine Mountain.

At the time of report preparation, only minimal exploration had taken place at the P. scopulinum location in the Tulameen River valley. Considering the sizable mineral holdings and various precious metals present, it may be only a matter of time before operations are undertaken; there is, however, uncertainty as to how soon such mining activity may be initiated. Mineral excavation and logging activities are likely to lead to upgrading of the present road and impact drainage.

Figure 5. Location of the single historic locality for Polystichum scopulinum (site 1) in relation to serpentine outcrops (black areas) in Newfoundland. Areas A, B and C represent areas of occurrence of the serpentine species Minuartia marcescens.

The largest population, at Britton Creek, is especially threatened by road upgrading since the site would either have a new cut established or could serve as a borrow pit. Forest fires are also a major threat in the Tulameen River valley. The second-growth forests have high fuel loads on the forest floor due to aggressive fire suppression activities. When forest fires occur under conditions of high winds and low fuel moisture in the understory fuels, they result in intense, inferno-like fires that destroy most understory vegetation. Even though the forests on the ultramafic sites are relatively open compared to immediately adjacent forests, high winds could easily carry a fire that would eliminate this rare fern.

In Quebec, it is suspected that botanical overcollecting had significantly reduced this disjunct population in the first half of the 20^th century, but it is now considered to be relatively stable within Parc de la Gaspésie. Due to the ultramafic properties of the soils at all sites, introduced species are of no concern. Since some of the fern clumps are on a trail, trampling may be a potential risk; however, since there is no monitoring of the site, the actual impact of such activity is unknown.

The site for the historic collection in western Newfoundland is in a relatively inaccessible location and is probably not at imminent risk if it is still extant.

Considering that the species only occupies a portion of the ultramafic sites at discrete elevational levels and exposure, it is possible that the species’ distribution may be affected by inherent characteristics that limit its occurrence and/or by variation in the distributional pattern of elements in the substrate.