t. site (020) 



1. Area occupied by population: ca. 80 

 acres. 



2. Estimated nvimber of individuals: 

 Thousands of plants (1990) . 



3. Density: Unknown. 



4. Presence of dispersed seeds: 

 Unknown . 



5. Evidence of reproduction: Flowering 

 plants observed. 



6. Evidence of population expansion or 

 decline: Unknown. 



DEMOGRAPHIC MONITORING STUDY: During 1990, three 

 permanent monitoring transects were established in 

 populations of C. lonqistylum on the Lewis and Clark 

 National Forest. The purpose of these transects is to 

 provide more detailed data on the life history and 

 population dynamics of C. longistylum . Data on 

 survivorship and reproduction are important for 

 understanding the biology of plants with limited 

 distributions, especially when attempting to ensure their 

 long-term preservation (Massey and Whitson 1980) . Data 

 may also indicate whether population sizes are declining, 

 which may be the result of infestation by the weevil 

 Rhinocyllus conicus . 



Methods including descriptions and maps of the study 

 sites, and the raw data are presented in Appendix B, pp. 

 78-91. First year results are summarized and presented 

 in Table 1, p. 19. 



RESULTS: Density of C. longistylum plants varied from 

 0.24 plants/m^ at Russian Creek to 2 . 1 plants/m^ at 

 Neihart. The percentage of flowering plants was highest 

 at Russian Creek (35%) , and was lower at Kings Hill and 

 Neihart (28% and 17%, respectively). However, the 

 reverse trend was observed for plants at the rosette 

 stage, with a greater percentage of rosettes occurring at 

 Neihart (83%) and reduced percentages observed at Kings 

 Hill and Russian Creek (71% and 64%, respectively) . The 

 highest number of large and medium rosettes were observed 

 at Neihart. 



Cirsium longistylum plants produced 10 to 16 heads per 

 plant. 



