Experimental Assessment of Factors Limiting Seedling Recruitment of an Amazonian Understory Herb

Understory herbs are an important and species‐rich component of tropical forests, but little is known about factors limiting recruitment of these herbs. In a Peruvian flood plain forest, we studied seedling recruitment of the widespread clonal herb Heliconia metallica . We analyzed natural recruitment and experimentally added seeds, excluded predators and removed the understory vegetation at occupied and unoccupied sites to test whether seed limitation, predation, disturbance, and the presence of mature conspecific plants influence seedling recruitment. The number of naturally recruited seedlings was higher at flooded sites and close to flowering H. metallica ramets. Predation caused considerable seed loss shortly after sowing. Seed survival strongly increased with the openness of a site, but was not affected by the presence of mature conspecifics. Seed addition increased the number of seedlings at both occupied and unoccupied sites. Two years after sowing, the number of established seedlings and their size increased with light availability at a site. In experimentally disturbed plots, light availability, seedling establishment, and survival were higher. The effect of disturbance on seedling survival was stronger at occupied sites, probably due to strong light competition from mature H. metallica plants. Herbivore damage on leaves of seedlings was lower at occupied sites, but seedlings grew faster at unoccupied sites. We conclude that seedling recruitment of H. metallica depends on natural disturbance and is limited by both seed availability and the presence of mature conspecific plants.