The remarkable levels of diversity in tropical forests are being gradually threatened and, in turn, an increase in secondary forests is occurring. Among the most conspicuous changes in forest structure is the proliferation of lianas. Lianas have an important impact on tree dynamics, by reducing tree growth and increasing mortality. In this study we asked whether the observed increases in liana abundance is also associated with a demographic advantage that emerges at early ontogenetic stages. We propose that the increases in liana number could be associated with higher survival and growth rates success at the seedling stage driven by a competitive advantage due to lianas investing more in resource capture instead of structure. We used a long-term data set of seedling plots in Puerto Rico combined with null model approach to test this hypothesis.
Results/Conclusions
We found that although lianas seem to have a survival advantage compared with trees during their first years, this advantage is not maintained for the entire study period and it is also highly variable across all sites. Furthermore, lianas that do survive do not grow faster than trees. Variation in liana survival was associated with the number of neighborhood lianas and diversity, but it was not necessarily affected by the total neighborhood density and total diversity. Our results show that lianas are able to attain higher survival rates than trees but this demographic advantage varies across years. Longer time series, therefore, are critical to understand changes in life-form composition for tropical forests.