Conclusion
Our study showed that no more wind-dispersed seeds arrived
into treefall gaps than into non-gap sites. Therefore, gaps may play
a neutral role in maintaining seed diversity. As far as we are aware,
this is the first community-wide comparison of seed limitation
between gaps and the understory in a subtropical forest. Dispersal
limitation affected most species in both gap and understory habitats;
both source limitation and dispersal limitation were speciesspecific.
The winning-by-default theory, which posits that not
because species are the superior competitors under the given
environmental conditions, but because better competitors never
established in that site, is supported by our study. An enormous
number of species can be maintained by strong seed limitation in
both gap and understory sites. Moreover, as seed limitation
increases due to increasing species richness or decreasing mean
fecundity, more sites might be won by forefeit rather than by
absolute dominance. As a result, population and community
dynamics might slow and ecological drift in species composition
may become a more important determinant of community
structure.