Intraspecific plant-soil feedbacks vary under field conditions among species in a tropical tree community

Premise Soil microbes can influence patterns of diversity in plant communities via plant-soil feedbacks. Intraspecific plant-soil feedbacks occur when plant genotype causes variation in soil microbial composition, resulting in differences in the performance of seedlings growing near their maternal plants versus seedlings growing near non-maternal conspecific plants. How commonly such intraspecific plant-soil feedbacks occur in natural plant communities is unclear, especially under variable field conditions. Methods We conducted an in situ experiment with four native tree species on Barro Colorado Island (BCI), Panama. Seedlings of each species were transplanted beneath their maternal tree or another conspecific tree in the BCI forest. Mortality and growth were assessed at the end of the wet season (∼4 months post-transplant) and at the end of the experiment (∼7 months post-transplant). Results Patterns of seedling performance varied among species and were inconsistent over time. Significant effects of field environment were detected for two of the four species: at the end of the wet season, Virola surinamensis seedlings had higher survival beneath their maternal tree than other conspecific trees, while the opposite pattern was found in Ormosia macrocalyx. However, these differences disappeared by the end of the experiment. Conclusions Our results suggest that intraspecific plant-soil feedbacks occur inconsistently under field conditions in tropical tree species and may have a limited role in determining seedling performance in tropical tree communities. Future studies are needed to elucidate the environmental and genetic factors that determine the incidence and direction of intraspecific plant-soil feedbacks in plant communities.