Frosted glass-whiskers (Sclerophora peronella) COSEWIC assessment and status report: chapter 4
Distribution
Global range
The current known global distribution of S. peronella includes Europe (Scotland, Germany, Moravia, Denmark, Sweden, Finland, Norway, France, Austria, Italy, and Estonia), where it had previously been considered endemic (Tibell 1994), the Caucases in Russia (Titov 1998), the United States, and Canada (Figures 2 and Figure3).
The species is rare to extremely rare throughout its Eurasian range. According to Tibell (pers. comm.), S. peronella “it is rare--becoming more so particularly in Central Europe now.” Fewer than 20 collections have been made by Eric Peterson and Jouko Rikkinen in western Oregon (Willamette Valley) (Figure 5).
Canadian range
In Canada, S. peronella is only known from one collection in British Columbia made in 1991 (Goward et al. 1996) and two collections in Nova Scotia discovered in 1998 (Selva 1999). Recent attempts to locate it on Prince Edward Island (Selva 1998a), as well as during fieldwork conducted by S. Selva in 2001, have been unsuccessful.
Given the small size of the apothecia of S. peronella and its apparent rarity throughout its global range, it is not surprising that it has been found only recently in Canada. The same can be said for its recent discovery in the United States, as well as Russia. Many of the collectors cited in this report, e.g., Leif Tibell, Trevor Goward, Steve Selva, Eric Peterson, and Jouko Rikkinen have been engaged in numerous and intensive lichen surveys in Canada and the United States and are all recognized as students of the calicioid lichens and fungi. Yet, they have managed to collect relatively few specimens of S. peronella. The species prefers a substrate and a microhabitat that is not foreign to the majority of calicioid taxa: It has been collected on exposed heartwood and/or bark of trees that would harbour any number of other calicioid species on a typical day of collecting. Sclerophora peronella collections can only be verified with certainty in the lab after the spores have been examined and chemical tests conducted on the thallus. However, the genus is in fact easily recognized in the field, which is enough to cause a collector to make a collection. Furthermore, any fieldwork that inventories calicioid lichens in general would be sufficient to confirm the species presence at a site, particularly as one of its substrates, exposed heartwood, is easily recognized. In other words, a targeted search is not necessary to provide good inventory data for the species.
Herbarium visits were made by S. Selva in 2001 (see “Collections examined”) to determine present collections and the locations of those collections. However, no records were discovered at the regional herbaria visited as part of this investigation.
The apparent rarity of S. peronella in British Columbia is supported by considerable negative evidence (Appendix 1), as calicioid diversity has been intensively studied in this province over a period of 30 years. In 1972 Leif Tibell (Tibell 1975) undertook a comprehensive assessment of calicioid richness at five localities across the southern third of the province, from Vancouver Island to Glacier National Park. A few years later Willa Noble initiated an intensive study of lichen floristics in the Coastal Douglas-fir Zone on southeastern Vancouver Island. This study yielded a total of 5500 specimens, including 12 calicioid species (Noble 1982). Irwin Brodo began studying the lichen flora of the Queen Charlotte Islands (Haida Gwaii) in 1967, and subsequently has amassed approximately 5000 collections from all portions of the archipelago, resulting in a report of nine calicioid species (Brodo, unpublished checklist). Brodo's investigations were supplemented by Tor Toensberg and Trevor Goward in 2003, though with no increase in the calicioid flora. In 1995 Steve Selva collected about 500 calicioid specimens from the Robson Valley of east-central British Columbia. More recently Trevor Goward has undertaken surveys of calicioid diversity at 21 localities in the southern half of the province, resulting in approximately 1500 calicioid collections out of a total sample size of about 6000 specimens.
All of the localities above are mapped in Figure 4 (see also Appendix 1). Though the localities themselves are small, collectively they represent a fairly thorough inventory of calicioid richness in the southern half of British Columbia. Moreover, as calicioid diversity appears to decrease northwards (Tibell 1994), it seems unlikely that the northern portions of the province will contribute additional species. Farther south, in the American Pacific Northwest, Eric Peterson (2000) and Jouko Rikkinen (2003) have collected 1500 and 2100 calicioid specimens respectively, with an emphasis on southwest Washington and northwest Oregon.
Additional search effort for calicioid lichens in the American Pacific Northwest was undertaken by the USDA Forest Service (J Harpel, pers comm 2005; USDA Forest Service, 2003). In two pilot studies, some 750 plots (Figure 5) were searched for a target set of bryophyte and lichen species that were closely associated with old-growth. Calicioid lichens were included on the list of target species. Some 20,000 bryophyte and lichen collections resulted from this study and Sclerophora peronella was not found.
Collecting for calicioid lichens in northeastern North America has, likewise, been both extensive and intensive over the past two decades (Figure 6). By far the greatest part of this work has been carried out by Steve Selva, who in the process has become the principal North American authority on the taxonomy and habitat ecology of the calicioid lichens and fungi. Formal and detailed surveys, typically requiring six to eight hours of fieldwork per site, have been completed by Selva in 77 northern hardwoods, spruce-fir, eastern hemlock, and eastern white cedar (Thuja occidentalis) forests throughout the Maritime Provinces, in upstate New York, and the northern New England States (Selva 2003). An indication of the intensity of these efforts is that 12 or more calicioid species per stand have been found at 33 different sites in the northeast. The two stands in Nova Scotia where S. peronella were found had the richest overall diversity of calicioids (21 and 20 species, respectively) of all investigated hardwood forests in eastern North America. The total number of calicioid specimens collected by Selva and other lichenologists in the region is >3,000.
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