Document: ELA-3-40-46
Factors affecting natural regeneration of native woody species in abandoned Panamanian pastures.
HOOPER, E.R.* 1,2,3, P.LEGENDRE 1 and R.CONDIT 2
Universite de Montreal, Montreal (Quebec) H3C 3J7 Canada 1
Smithsonian Tropical Research Institute, Balboa, Republica de Panama 2
McGill University, Montreal, Quebec, Canada 3
Abstract:
Following tropical pasture abandonment, natural regeneration of rainforest species is often delayed. We studied woody plant establishment in abandoned Panamanian pastures, focusing on two hypothetical barriers: Lack of seed dispersal, and competition with the exotic grass Saccharum spontaneum. Woody seedling abundance was measured in a factorial experiment combining distances from adjacent forest and mowing treatments of the Saccharum. Factors including soil moisture, photosynthetically active radiation, time since fire, herbivory, slope, and Saccharum biomass were also measured. Distance-based redundancy analysis identified significant (P < 0.005) effects of distance from the forest and time since fire on woody regeneration. Small-seeded wind and bird- dispersed species abundance declined with distance from the forest and time since fire, whereas mammal-dispersed species generally increased. Experimental addition of 20 native tree species indicated that large-seeded species had significantly higher germination and survival in the abandoned pastures, whereas most species found naturally regenerating were small-seeded. We interpreted this to indicate that seed dispersal limitations are most severe for the large-seeded, animal-dispersed species. The effect of spatial heterogeneity on seed dispersal was assessed by calculating the distance of each regenerating woody seedling to the nearest adult conspecific, forest edge, woody perch, large-leaved monocot and shrub and these distances were utilized in multiple logistic regression modelling. We obtained significant (P < 0.01) models following Bonferroni adjustment for almost all the abundant species, which we discuss in relation to seed dispersal mechanisms. These results underline the importance of seed dispersal in the regeneration of abandoned Panamanian pastures.
Keywords: Neotropical forest regeneration, abandoned pastures, seed dispersal, redundancy analysis
This abstract is being presented at: 10:30 AM in session:
PLANT DEMOGRAPHY