A study of the ecological life history of Ceropia peltata L. : an early secondary successional species in the rain forest of Puerto Rico

The ecological life history and population dynamics of Cecropia peltata L., a pioneer species in the lower montane rain forest of the Luquillo Mountains of Puerto Rico, were described. Survival, factors affecting survival and processes associated with the life cycle stages; seed, seedling, juvenile and mature plants were investigated in order to determine the most critical period in development.

Observations of flowering and fruiting were made monthly, dispersal agents were noted, forest soil was examined for the presence of Cecropia seed, trees at all stages were harvested for biomass measurements, seed longevity examined and seedling, sapling and mature trees were measured to obtain growth rates. The effect of open or previously cultivated field, gap and forest environments upon germination success and seedling survival were investigated. Laboratory germination studies were conducted to determine the significance of light in the germination process. Information concerning survival was obtained from censuses of 22 disturbed areas occupied by Cecropia ranging from 6 months to 14 years since time of disturbance and a survivorship curve and life table constructed.

Peak flowering and fruiting occurred during the dry season. Cecropia may produce as many as 6 to 7 million viable seeds during its reproductive lifetime. Seeds are extremely small and are disseminated by birds and bats frequenting both forested and gap areas. Forest soil of the El Verde area contained large numbers of viable seeds which germinated in response to gap conditions. Success of germination and seedling survival was greatest in the gap environment. No germination occurred and no seedlings survived within the forest and germination was much reduced in the open field. Laboratory studies indicated that light was a significant factor influencing germination. Growth in height of dominant seedlings and saplings is rapid and reproductive maturity is reached at an early age. As is typical of a pioneer species, the majority of mortality occurred very early in life, the greatest between germination and seedling establishment.

Cecropia may be considered a "gap opportunist" in the tabonuco forest because, although widely dispersed, its presence is restricted to gaps by the absence of germination in the forest; therefore, its persistence in the forest is dependent on the frequent formation of gaps and the ability to colonize these rapidly.