Transplant experiments reveal edge effects and inconsistent maternal effects on seedling performance in the pioneer tree Ficus tonduzii (Moraceae)

Abstract

Edge effects caused by forest fragmentation may impact the growing environment of both seedlings and maternal trees. Early regeneration stages are of special concern but how maternal origin, edge effects, light environment, and distance from reproductive conspecific trees, as expected from the Janzen-Connell hypothesis, may affect seedling performance, has rarely been studied simultaneously. The goal of this study was to experimentally assess the relative importance of the aforementioned factors for seedling performance of an animal-dispersed, pioneer tree species Ficus tonduzii (Moraceae) in premontane wet forest fragments in Costa Rica. Seedlings from known maternal origins were grown in a screen house before being transplanted at two distances from focal trees in forest fragments. Both maternal trees (home) and non-maternal reproductive conspecific (away) were used as focal trees. In the screen house, seedling size and inherent growth differed by maternal origin. In the forest, distance from the nearest forest edge was the primary factor affecting survivorship and growth of transplants. Additionally, inconsistent maternal effects were observed. While seedlings from a particular maternal origin showed reduced growth in the screen house, those same seedlings showed enhanced growth once they were transplanted in the forest. In contrast, light environment or distance from the reproductive conspecific tree did not predict seedling performance. Home disadvantage was observed for one tree, which underlined the significance of seed dispersal. The results from this case study emphasize the importance of considering both edge effects and stage-specific maternal effects for successful species regeneration and restoration practices in fragmented landscapes.