Eastern prairie fringed-orchid COSEWIC assessment and status report: chapter 3

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Introduction

In the original status report, Brownell (1984) recommended a national status of "rare" for Platanthera leucophaea due to alarming trends in population decline and extirpations across its range and the existence of only 13 populations in Canada. In 1986, COSEWIC designated the species as rare citing the reason as “limited to 12 wetland colonies in Ontario”. This rationale was added by the COSEWIC Plant Subcommittee in recognition that the status report and its recommendation was based upon the inclusion of an extensive population in Manitoba that was later separated as the new species, Platanthera praeclara. In 1990 terminology for the “rare” category was changed to “vulnerable”, and in the year 2000 was changed to “special concern”^Footnote1.

Since the 1986 status designation, many people have expressed concern that the species has declined substantially. To some extent, this may be a consequence of fluctuation in population size from year to year at a particular site. The Eastern Prairie Fringed-orchid is notorious for fluctuations in population size (Sheviak and Bowles 1986, Denny 1988, Bowles 1991). On the other hand, drastic changes in habitat at some sites suggested a possible trend toward increasing threat. In 1989, Platanthera leucophaea was officially designated as threatened under the United States Endangered Species Act of 1973 (Harrison 1989).

Subsequent to Brownell (1984), some research has been done on Eastern Prairie Fringed-orchid, status has been updated in various parts of the U.S. range, and recovery plans have been prepared. A thorough and range-wide investigation is beyond the scope of this report and so is a complete analysis of recovery actions and management.  It is the purpose of this report to evaluate the current status in Canada, particularly with regard to changes since previous designation, and to bring together the more recently acquired information that may be useful in conservation.