Elasticity analysis 



Elasticities for the three sites for the four annual transitions are 

 presented in Table 7. Growth and survival of plants in the non-reproductive 

 stages accounted for ca. 50% of equilibrium population growth (X) at all three 

 sites. Growth and survival of reproductive plants was responsible for 36% of 

 X at Charleys Gulch but less than 20% at Lime Gulch and Vipond Park. On the 

 other hand, recruitment from seed accounted for 34% and 36% of X at these 

 latter two sites but only 16% at Charleys Gulch (Table 7). Adult 

 (reproductive) growth and survival was the most important transition at 

 Charleys Gulch, while recruitment was predominant at Lime Gulch and Vipond 

 Park. 



Discussion 

 Life history 



Arabis fecunda is a relatively short-lived perennial; only ca. half of 

 the plants that establish live for more than two years, and only ca. one-third 

 live for four years or more. Annual recruitment is generally high; the ratio 

 of new recruits to survivors varied from 0.09 to 2.05 with means for 1989-93 

 between 0.31 and 0.95. Mortality of new recruits is also high; in 1991-93, it 

 varied from ca. 20-50%. Fecundity is generally high; reproductive A^ fecunda 

 plants produced an average of 340-500 seeds per year. Plants that bolted 

 produced ca. 2.5 times as many seeds per year as axillary flowering plants but 

 had much higher mortality. Seeds become ripe in late spring or early summer 

 and germinate readily without stratification. These results suggest that most 

 seeds germinate in the fall, of the same year that they are produced. Seeds 

 from Charleys Gulch also show high germination in the cold and dark, 

 suggesting that at this site only a transient type II seed bank is formed 

 (sensu Thompson and Grime 1979). On the other hand, cold/dark conditions 

 induce dormancy in seeds from Vipond Park; thus, A_^ fecunda probably does have 

 a long-term seed bank at this site. 



12 



