The effects of plant distribution and frugivore density on the scale and shape of dispersal kernels

MORALES, J. M.; CARLO, T. A.

Ecology

Año: 2006 vol. 87 p. 1489 - 1496

0012-9658

For many plant species, seed dispersal is one of the most important spatialdemographic processes. We used a diffusion approximation and a spatially explicit simulationmodel to explore the mechanisms generating seed dispersal kernels for plants dispersed byfrugivores. The simulation model combined simple movement and foraging rules with seed gutpassage time, plant distribution, and fruit production. A simulation experiment using plantspatial aggregation and frugivore density as factors showed that seed dispersal scale waslargely determined by the degree of plant aggregation, whereas kernel shape was mostlydominated by frugivore density. Kernel shapes ranged from fat tailed to thin tailed, but mostshapes were between an exponential and that of the solution of a diffusion equation. Theproportion of dispersal kernels with fat tails was highest for landscapes with clumped plantdistributions and increased with increasing number of dispersers. The diffusion modelprovides a basis for models including more behavioral details but can also be used toapproximate dispersal kernels once a diffusion rate is estimated from animal movement data.Our results suggest that important characteristics of dispersal kernels will depend on thespatial pattern of plant distribution and on disperser density when frugivores mediate seeddispersal.