fecunda plants in each 1 m z plot. At Charleys Gulch, we read two 

 transects (10 and 12 plots), and at Birch Creek, we read one 

 transect (22 plots) . All of the transects were located in areas 

 subject to livestock grazing. Transects were read on May 19-20, 



198! 



RESULTS AND DISCUSSION 



Long Term Monitoring Study 



A summary of the data from two years of the long-term 

 monitoring study is presented in Table 1. At both sites the 

 density of plants was slightly lower in 1988 than in 1987. In 

 addition, the number and percentage of fruiting plants was 

 appreciably lower in 1988 than in 1987. At both sites, however, 

 the total number of fruits per fertile plant, and the number of 

 fruits per inflorescence, was greater in 1988. These results 

 probably indicate various stress responses to the drought 

 conditions that began in 1987 and continued into 1988. 



Size and fecundity data for individual Arabis fecunda plants 

 over the two-year period are presented in Appendix A. These data 

 are summarized in Table 2. It is too early in the study to 

 determine whether these populations are stable, growing or 

 declining; nonetheless, it is worth noting some trends. At 

 Charleys Gulch, where only one plant was lost to apparent soil 

 slumping, recruitment and adult mortality were approximately 

 equal in both years. At Birch Creek, where 15 plants were lost 

 to soil slumping, adult mortality was appreciably higher than 

 recruitment. In most cases of soil slumping at Birch Creek, we 

 observed hoof prints of cattle in the slumped areas. If these 15 

 plants had not been lost, mortality and recruitment would have 

 been approximately equal. At Charleys Gulch, apparent seedling 

 survival was greater than seedling mortality. However, these 

 results have limited meaning because appreciable seedling 

 mortality may have occurred prior to reading the transects in 

 late May. 



Knapweed Removal Study 



One year after removing spotted knapweed plants from the 

 experimental plots, its cover was approximately equal to that in 

 the control plots (Table 3) . This result can be explained in 

 part by new recruitment of seedlings and in part by a failure to 

 completely eradicate all plants in 1987. Nonetheless, the 

 competitive ability of knapweed in the removal plots should have 

 been reduced during at least part of the 1987 growing season. 



