Niche differentiation is a prominent hypothesis explaining the maintenance of tree species diversity in tropical forests (Connell 1978). It suggests that different species are best suited to different habitats in which they are completely dominant and more abundant than in less suitable habitats (Harms et al. 2001). In addition, distribution patterns of tropical trees are generally more clumped or aggregated than random (Condit et al. 2000). Furthermore, environmental heterogeneity (difference in soil, elevation, slope, etc.) may obscure aggregated distribution of plant species across spatial scales (Harms et al. 2001) . Therefore, it is difficult to assess whether aggregated patterns are caused by local dispersal, local interaction or environmental heterogeneity. |
