Tropical Tree Seed Dynamics Program

Program Directors: Dr. Diane De Steven

Over the past 20 years, I have carried out two projects directly related to ESP’s terrestrial biological monitoring on Barro Colorado Island. 

1. Phenological patterns of tropical palms     

From 1980-1983, I supervised a collaborative study of temporal variation in flowering and fruiting behavior of the Barro Colorado Island palm flora (13 spp).   In contrast to expectations of constancy, the results showed that palm species varied substantially in degree of seasonality and within-population synchrony, despite their uniform growth morphology.  This study provided one of the early demonstrations of  El Niño impacts on BCI forest phenology.
   

Publications from project:

De Steven, D., D.M. Windsor, F.E. Putz, & B. de Leon 1987.  Vegetative and reproductive phenologies of a palm assemblage in Panama.  Biotropica 19:342-56.

De Steven, D. & F.E. Putz 1985.  Mortality rates of some rain forest palms in Panama.  Principes 29:162-66. 

2. Dynamics of tropical tree seed production and seedling recruitment

This long-term study was initiated in 1987 to build upon an existing ESP phenology census of tree-level annual seed production by several common canopy species on BCI.   For 11 years (1987-1997), seedling establishment, survival, and growth were monitored in permanent plots placed at individual focal trees of 3 species (Quararibea asterolepis, Tetragastris panamensis, Trichilia tuberculata).  This has produced a rare long-term dataset linking seedling establishment to seed production at both population and individual tree scales, within and between years.  The study has provided new insights into spatial and temporal variation in seedling recruitment for mature-forest species that appear ecologically similar, and into the possible contribution of early limiting factors to subsequent population dynamics.
 

Publications from project:
De Steven, D. 1994.  Tropical tree seedling dynamics: recruitment patterns and their population consequences for three canopy species in Panama.  J. Trop. Ecol. 10:369-83.

Gilbert, G.S. and D. De Steven 1996.  A canker disease of seedlings and saplings of Tetragastris panamensis (Burseraceae) caused by Botryosphaeria dothidea in a lowland tropical forest.  Plant Disease 80:684-871

Engelbrecht, B.M.J., Wright, S.J. and D. De Steven 2002.  Survival and ecophysiology of tree seedlings during El Niño drought in a tropical  moist forest in Panama.  J. Trop. Ecol. 18:569-79. 

De Steven, D. and S.J. Wright 2002.  Consequences of variable reproduction for seedling recruitment in three neotropical tree species.  Ecology 83:2315-27.