PARENT SESSION
Oral Session #13: Plant Ecology: Light Relationships. Presiding: J. Rebbeck.
Monday, August 6, 2001. 1:00 PM to 4:30 PM. Hall of Ideas P&Q.
Influence of a dominant palm, Oenocarpus mapora on seedling establishment in a tropical moist forest of Panama.
Farris Lopez, Krista1, Denslow, Julie2, Passmore, Heather1, 1 2
ABSTRACT- We examined the impact of the palm, Oenocarpus mapora, on the establishment of woody seedlings in a tropical moist forest. Specifically, we asked a) what are the impacts of Oenocarpus on light availability and leaf litter accumulation; b) how does Oenocarpus affect seedling abundance; c) do seed size and shade tolerance characteristics of seedling species differ between palm and non-palm sites? We conducted a transplant experiment to determine the effect of Oenocarpus and its leaf litter on growth and mortality rates of seedlings. Seedling composition, light availability, leaf litter and palm presence were measured in 1-m2 contiguous plots along transects in three forest stands. Leaf litter depth was significantly higher and light availability was significantly lower in plots where palms were present. Logistic regression analyses showed the presence of palms decreased the probability of seedling presence. The probability of seedling presence increased with light availability. Seed size was significantly larger among seedlings under palms versus among seedlings in non-palm sites. Survivorship and biomass of seedlings were significantly lower under palms. We conclude that low light availability and high leaf litter accumulation produce poor establishment conditions for many seedlings. Oenocarpus may act as an environmental filter selecting against smaller seeded and less shade tolerant species, thereby influencing the species composition of the advanced regeneration.
KEY WORDS: Oenocarpus mapora, seedling establishment, tropical forest, species dominance