Positive association between Bromelia balansae (Bromeliaceae) and tree seedlings on rocky outcrops of Atlantic forest

Abstract

Abstract:Plant facilitation can improve the diversity of plant communities in several ecosystems, especially in stressful environments. The establishment of tree species on rocky outcrops can be limited by several biotic and abiotic factors. The richness and abundance of forest trees species on rocky outcrops surrounded by a large forest remnant in south Brazil were correlated with the cover of Bromelia balansae, a spiny stoloniferous species commonly occurring at forest–grassland transitions. Sixty plots were established on three flat rocky outcrops (20 in each). In each plot the coverage of bromeliads was estimated into three classes (0%, 1–50% and 51–100%) and all seedlings (individuals 10–30 cm in height) were counted and identified. ANOVAs with randomization tests were performed to establish the effect of different bromeliad cover classes on the richness and abundance of seedlings. The cover of bromeliads was positively related to the richness and abundance of young pioneer tree species. Evidence suggests that B. balansae can act as a nurse plant for tree seedlings, but manipulative experiments are needed to confirm this.