11 



plants/m^ at Russian Creek to 2 . 6 plants/in^ at Kings Hill. 

 Much of the increase at Kings Hill was due to high seedling 

 establishment in areas where rodent activity had 

 substantially disturbed the plot. However, this same 

 activity eliminated several of the larger rosettes that were 

 present in this same section of the plot. Disturbance is 

 beneficial to seedling establishment, but may eliminate 

 rosettes before they mature to the flowering stage. 



Although the highest number of large and medium rosettes was 

 observed at Neihart in 1990, only Russian Creek had 

 flowering plants in the plot in 1991. At Russian Creek, 

 flowering was reduced from 35 percent in 1990 to 6 percent 

 in 1991. All of the plants that did flower in 1991 were 

 recorded as large rosettes in 1990. The percentage of 

 medium and large rosette plants increased in 1991 at Russian 

 Creek, decreased at Kings Hill, and remained at nearly the 

 same levels at Neihart in 1991. Casual observations by the 

 author of sites across the Little Belt Mountains confirmed 

 that there were fewer Cirsium plants flowering in 1991. 

 This reduction in flowering could have been the result of 

 climatic influences (May and June of 1991 were very wet and 

 cold, or cyclical patterns of flowering. 



In 1991, observations on grazing and other impacts to plants 

 were made at all three sites. At Russian Creek, none of the 

 rosettes had been grazed, although three had dead leaves at 

 the base and the vegetative portion of one was moldy. At 

 Kings Hill, two of the rosettes were grazed lightly, while 

 twelve had disappeared due to rodent activity. The highest 

 amount of herbivory occurred at Neihart, due in part to its 

 proximity to a seep used by cattle located approximately 0.1 

 mile south of the plot (pers. obs.). Here, 31% of the 

 rosettes had been grazed, and the canopy cover of other 

 plant species had been significantly reduced. How grazing 

 ultimately affects the ability of these rosettes to reach 

 maturity should be uncovered through continued monitoring. 



At Neihart, the negative growth rate was mainly due to the 

 high loss of small, medium or large rosettes (54%) , and a 40 

 percent recruitment rate. Whereas at Russian Creek, the 

 negative growth rate was mainly due to the loss of plants 

 that had flowered in 1990 (35%) , and a 31 percent 

 recruitment rate. Alternatively at Kings Hill, where 31 

 percent of the small, medium or large rosettes were lost 

 between 1990 and 1991, and another 33 percent loss came from 

 plants that had flowered in 1990, the recruitment rate (76%) 

 was significant enough to offset these losses, resulting in 

 a positive change in population size. 



