DEMOGRAPHY AND LIFE-HISTORY CHARACTERISTICS OF THE RARE KACHINA DAISY(ERIGERON KACHINENSIS, ASTERACEAE)

Erigeron kachinensis is a rare endemic of the Colorado Plateau regions of southeastern Utah and southwestern Colorado. It occurs in small, i solated alcoves (recessed areas in canyon walls) at seeps arising alon g canyon walls in sandstone substrates. One hundred randomly selected individuals of E. kachinensis within each of six alcoves in Natural Br idges National Monument, San Juan County, Utah, were monitored for 5 y r (1990-1994). Survival of the 600 individuals was followed over the m onitoring interval. Vegetative and reproductive parameters were assess ed for the survivors each year. Mortality varied among the study alcov es and individual size-classes. Mortality was heavily concentrated in the smaller size-classes. Growth rate accelerated with increasing size -class. Survival rate also increased with increasing size-class. Plant s are long-lived; however, longevity is still unknown since mortality was not observed in the largest size-class. Fecundity was greatest for the largest size-classes, yet over 80% of the annual seed production came from the three smallest size-classes due to abundance of individu als in these size-classes. Populations varied with respect to plant si ze and resistance to environmental stressors. Matrix analysis demonstr ated a finite rate of population growth of 0.75. However, observed siz e-class distributions of the six study populations over 5 yr of observ ation have never been stable. Maintenance of viable populations of the Kachina daisy is dependent on management actions that minimize distur bances (natural or anthropogenic) in the fragile hanging gardens that support the species.