Demography and Life History Variation of Puya Dasylirioides, a Long-Lived Rosette in Tropical Subalpine Bogs

Publisher Website
Google Scholar
Abstract
Demographic and growth measurements taken from 1974-1980 for Puya dasylirioides Standley (Bromeliaceae) in bogs of Costa Rica reveal that after an estimated mean of 36 yr of vegetative growth, a rosette (ramet) reproduces once and dies. The amount of vegetative propagation, occurring many years prior to reproduction, varies greatly within and among sites. Thus ramets are monocarpic; a genet (genetic individual) may be polycarpic. Reproductive rosettes vary greatly in radius (20-72 cm); they are larger in the margins than the center of bogs. The number of mature fruits varies greatly among rosettes (50-1224) and rises exponentially with an increase in rosette radius. Recruitment of new rosettes from seed is uncommon and sporadic in space and time. Germination sites are restricted and Puya seedlings compete poorly where grasses and sedges are common. Survival probabilities rise as rosettes increase in size. After they attain 11 cm radius, requiring an estimated 12 yrs, almost no rosettes die prior to reproduction. Of 334 rosettes tagged in 1975, 102 died in four years, while 12 new rosettes arose form seed. As these bogs undergo natural succession toward more mesic conditions, or undergo accelerated succession due to human disturbance of their drainage, populations of Puya dasylirioides appear to decline rapidly.