Abstract
We assessed the relative importance of dispersal limitation, environmental heterogeneity and their joint effects as determinants of the spatial patterns of 229 species in the moist tropical forest of Barro Colorado Island (Panama). We differentiated five types of species according to their dispersal syndrome; autochorous, anemochorous, and zoochorous species with small, medium-size and large fruits. We characterized the spatial patterns of each species and we checked whether they were best fitted by Inhomogeneous Poisson (IPP), Homogeneous Poisson cluster (HPCP) and Inhomogeneous Poisson cluster processes (IPCP) by means of the Akaike Information Criterion. We also assessed the influence of species’ dispersal mode in the average cluster size. We found that 63% of the species were best fitted by IPCP regardless of their dispersal syndrome, although anemochorous species were best described by HPCP. Our results indicate that spatial patterns of tree species in this forest cannot be explained only by dispersal limitation, but by the joint effects of dispersal limitation and environmental heterogeneity. The absence of relationships between dispersal mode and degree of clustering suggests that several processes modify the original spatial pattern generated by seed dispersal. These findings emphasize the importance of fitting point process models with a different biological meaning when studying the main determinants of spatial structure in plant communities.
Highlights
Ecologists have widely accepted that most of the mechanisms acting in plant populations and communities leave an imprint in their spatial structures [1,2]
Inhomogeneous Poisson cluster process best described the spatial patterns of 63% of the species, whereas HPCP and Inhomogeneous Poisson process (IPP) were the best models for 20% and 17% of them, respectively (Table 1)
Our findings clearly corroborate that aggregation is the norm for conspecific spatial patterns in this forest [11,30] since the spatial patterns of 229 woody plant species present in the Barro Colorado Island Forest Dynamics Plot (BCI) in 1995 were aggregated, regardless of their dispersal syndrome
Summary
Ecologists have widely accepted that most of the mechanisms acting in plant populations and communities leave an imprint in their spatial structures [1,2]. By studying the spatial patterns of plant populations and communities it is possible to infer which are their major underlying processes [3,4,5]. Environmental heterogeneity modify the spatial pattern of woody plants for Tropical Forest Science, the Smithsonian Tropical Research Institute, the John D. and Catherine T.
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