Results 



Vegetation 



Mean canopy cover estimates for common vascular plant species are 

 presented in Table 1, Total basal vegetation cover was lower at Charley's 

 Gulch compared to Lime Gulch or Vipond Park (Table 1). Graminoids were common 

 at Lime Gulch, but forbs were more common at the other two sites. Amounts of 

 bare soil were highest at Charleys Gulch, intermediate at Lime Gulch, and 

 lowest at Vipond Park, while rock was more abundant at Vipond Park (Table 1). 



Population Growth 



Density of Arabis fecunda varied among sites and years (Fig. 1). 

 Population size was more variable at Lime Gulch and Vipond Park than at 

 Charleys Gulch. The coefficient of variation for density for 1989-93 was 22% 

 at Lime Gulch and Vipond Park but was 18% at Charleys Gulch. 



Equilibrium population growth rate (X) also varied among sites and years 

 (Table 2). X was lowest and least variable at Charleys Gulch. In 1989 there 

 were no reproductive plants at Lime Gulch, but there were many in 1990. Thus, 

 1989-90 was a year of exceptional growth at Lime Gulch, but X was nearly 

 constant in the three ensuing year. X showed the most consistent high 

 variation at Vipond Park. 



Recruitment 



The ratio of new Arabis fecunda recruits to number of survivors was 

 significantly greater at Vipond Park compared to Charleys Gulch for all four 

 transition years (Fig. 2). In most years Vipond Park had higher recruitment 

 than Lime Gulch, and Lime Gulch had higher recruitment than Charleys Gulch 

 (Fig. 2). When all four years are pooled, the ratio of new recruits to number 

 of survivors is 0.31 for Charleys Gulch, 0.55 for Lime Gulch, and 0.95 for 

 Vipond Park, and these differences are significantly different between all 

 possible pairs of sites (P<0.001). 



