Cryptic paw (Nephroma occultum) COSEWIC assessment and status report: chapter 9
Special Significance of the Species
Nephroma occultumis endemic to western North America. Canada accounts for more than 50% of the range of this species. Only five Canadian localities are protected from forest harvesting. N. occultum is among a suite of rare and uncommon lichens and bryophytes that are dependent upon humid, old growth forests, and exhibit an unusual coastal-inland disjunct distribution. Throughout its range, the habitat of N. occultum is in progressive decline due to forest harvesting and insect infestation. This trend is most pronounced in the inland areas where suitable habitat is already geographically restricted by climate.
With its recognition in Canada and the United States of America as a species requiring special conservation consideration (Goward 1995a, FEMAT 1993), Nephroma occultum has received substantial attention from lichen researchers. Several ecological studies and distribution extensions on N. occultum have been published in the past 10 years (Goward 1994, 1995a, 1995b; Sillett 1995; Sillett and Neitlich 1996; Goward and Pojar 1998; Sillett and Goslin 1999; Rosso et al. 1999, 2000; McCune et al. 2002; Zavarzin and Timdal 2004). Among lichens, Nephroma occultum has become one of the very few “flagship” species, and has acted as a focal species for the conservation of many rare and endangered old growth dependent lichens, bryophytes, vascular plants, and even entire forests. Formal protection relating to forest management in the United States of America (which requires lichen surveys; FEMAT 1993) has led to the discovery of over 190 new populations since 1994. Federal listing in Canada by COSEWIC did not result in mandatory lichen surveys in regions with potential N. occultum habitat where forest harvesting was planned; in contrast, only 24 populations have been discovered in Canada in the past 10 years.
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