Porsild's bryum (Haplodontium macrocarpum) COSEWIC assessment and status report: chapter 8

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Limiting Factors and Threats

Mielichhoferia macrocarpa is limited by a number of factors relating to establishment of new populations including dispersal, substrate restriction and intrinsically low or slow establishment that limits the species to sites unoccupied by other mosses.

In the Cadomin area of Alberta, the occupied seepy cliff sites are very vulnerable to changes in upstream hydrology such as siltation of streams caused by excessive off-road vehicle use in headwaters. In this area outside the Wildland Park, coal mining exploration (planned Cheviot Mine) and road development have also threatened populations, notably the population called Mac1, which is the largest contiguous population of the species in Canada (Appendix 1). Road construction and blasting could cause large pieces of the intrinsically unstable rock to fall from cliff habitats taking Mielichhoferia macrocarpa colonies with them. Populations of the species in Alberta and British Columbia are certainly in the greatest danger from development and recreational use of habitats.