Abstract
The competition-colonization trade-off, by which species can partition spatial niches, is a potentially important mechanism allowing the maintenance of species diversity in plant communities. We examined whether there was evidence for this trade-off among tree species in a subtropical forest and how it correlated with eight functional traits. We developed and estimated a metric for colonization ability that incorporates both fecundity and seed dispersal based on seed trap data and the sizes and distributions of adult trees. Competitive ability was estimated as survival probability under high crowding conditions based on neighborhood models. Although we found no significant relationship between colonization and competitive abilities, there was a significant negative correlation between long distance dispersal ability and competitive ability at the 5 cm size class. Colonizers had traits associated with faster growth, such as large leaves and low leaf lamina density, whereas competitors had traits associated with higher survival, such as dense wood. Our results imply that any trade-off between competition and colonization may be more determined by dispersal ability than by fecundity, suggesting that seed dispersal is an important contributor to diversity maintenance. Future work should test how competitive ability covaries with the components of colonization ability, as we did here.
Highlights
The competition-colonization trade-off, by which species can partition spatial niches, is a potentially important mechanism allowing the maintenance of species diversity in plant communities
We examined the relationship of the two components of colonization ability with competitive ability, to evaluate whether a competition-colonization trade-off might be driven more by fecundity or dispersal
The correlation coefficients based on mean estimates of colonization and competitive abilities of the species were negative for all tree sizes, the bootstrapped confidence intervals on the correlation coefficients always included zero (Fig. 1)
Summary
The competition-colonization trade-off, by which species can partition spatial niches, is a potentially important mechanism allowing the maintenance of species diversity in plant communities. Later models used the more realistic assumption of replacement competition, in which colonizers of a site compete with each other as juveniles to win the site, assuming that the adult dies[5,6] In such models, purely spatial subdivision is insufficient for species to stably coexist, and some form of environmental heterogeneity is required, along with appropriate trade-offs involving colonization[6].The necessary environmental heterogeneity can take a variety of forms, including variation in resource-limitation stress[1], the density of patches suitable for recruitment[6], or successional niches[5]. Larger-seeded animal-dispersed species can be well-dispersed[19], they may not always be better colonizers, since larger seed size is often associated with reduced fecundity[1,18]
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