4 

 RESULTS AND DISCUSSION 



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

 monitoring is presented in Table 1. Fecundity, as measured by 

 percentage of plants fruiting, fruits/plant, fruits/inflorescence 

 and seeds/fruit increased or was stable at Charley's Gulch in 

 1990 compared to 1989; however, these same parameters were all 

 noticeably lower at Birch Creek. Population growth was positive 

 at Charley's Gulch but negative at Birch Creek. 



In 1989 most of Montana received above-normal precipitation 

 in late summer and early autumn, and although snowpack was light 

 in southwestern Montana during the following winter, late spring 

 precipitation was also above average. Since germination of 

 Arabis fecunda seed occurs readily without any cold treatment, 

 the wet period in late summer and early autumn should have 

 resulted in high levels of recruitment and strong seedling 

 growth. Both higher than average levels of autumn and spring 

 precipitation should have resulted in an increase in fecundity. 

 Arabis fecunda populations at Charley's Gulch did experience an 

 increase in both recruitment and fecundity. The negative 

 response at Birch Creek, only five miles distant, is difficult to 

 explain. Negative growth may be the result of mortality due to 

 disturbance of the habitat by livestock or ungulate grazers, but 

 we did not observe recent slumping of the soil as in 1988. 

 Future observations may help explain this dilemma. 



