INTRODUCTION 



Passage of the Federal Endangered Species Act of 1973 has 

 fostered compilation of herbarium collection records and baseline 

 species surveys to determine the location and size of populations 

 of rare plant species. Species 1 status and listing priority are 

 initially based on range of distribution and habitat as 

 determined by collection records and surveys. However, knowing 

 the species 1 population locations and sizes at any given time is 

 necessary but not sufficient for determining species status. 

 Status is also conditioned by associated risks of destruction, 

 modification, or curtailment of habitat and range; disease or 

 predation; natural or manmade factors affecting its continued 

 existence; the inadequacy of existing regulatory mechanisms; and 

 overutilization for commercial, recreational, scientific or 

 educational purposes, as identified in Section 4 of the Act. 

 Demographic monitoring can document population dynamics and 

 critical life history stages (Menges 1986) , directly or 

 indirectly providing insights into status questions. 



Cirsium lonqistvlum Nutt. (Long-styled thistle) is currently 

 placed in Category 2 as a candidate for federal listing as 

 threatened or endangered (58 FR 51144). It is a species endemic 

 to four "island" mountain ranges with calcareous bedrock in 

 Montana, spanning six counties (Lesica and Shelly 1991, Poole and 

 Heidel 1993) . Systematic survey of Cirsium lonqistvlum was 

 initiated in 1990 because it was initially known from few sites 

 in the Little Belt Mountains. This also made it a priority for 

 collecting baseline demographic information (Schassberger 1991) . 

 Three permanent monitoring plots were established to characterize 

 life history of Cirsium lonqistylum (Schassberger 1991, 

 Schassberger and Achuff 1991) . They have been reread in the 

 following three years (Roe 1992, Poole and Heidel 1993) including 

 results represented in this report. 



While Cirsium lonqistylum was once thought to be highly 

 restricted in its numbers and distribution, it has now been found 

 to recur throughout the Little Belt and Big Belt Mountain ranges, 

 and in at least trace amounts in the Castle Mountains and Elkhorn 

 Mountains. In the course of this baseline survey and monitoring 

 work, taxonomic questions were raised, potential impact of weevil 

 infestation by Rhinocyllus conicus in the flower head was 

 identified as a concern, and major differences in disturbance 

 regimes were observed across its range of habitats. 



Taxonomic questions surrounding Cirsium lonqistvlum underlie all 

 other status questions. 



The most recent 1993 monitoring work was incorporated the 

 recommendations and study design considerations previously 

 mentioned in order to interpret monitoring results and lead to 

 status recommendations. 



