Avian fruit ingestion differentially facilitates seed germination of four fleshy-fruited plant species of an Afrotropical forest

Background and aims The effects of gut treatment on the germination of animal-dispersed seeds are critical for the recruitment of many fleshy-fruited plant species, and hence for forest dynamics. However, these effects remain poorly studied especially in African plant species. In this paper, we aim to investigate the effects of gut treatment on the germination capacity and mean germination time of four common plant species of an Afrotropical cloud forest. Methods We fed Xymalos monospora fruits to its three main avian dispersers to investigate different responses among frugivore species. Next, fruits of four plant species were fed to the most dominant avian disperser, Andropadus milanjensis, to compare responses among plant species. Germination capacity and mean germination time were compared among gut-passed seeds, manually depulped seeds and intact fruits. Key results Germination of Xymalos monospora seeds was up to nine times more likely and almost twice as fast after bird ingestion compared to intact fruits. An increase in germination capacity, but not in mean germination time, was also detected in four sympatric plant species after ingestion by Andropadus milanjensis. The positive effects of seed ingestion on germination was mainly by fruit pulp removal; only one plant species showed an indication of the combined effect of fruit pulp removal and seed coat scarification on its germination success. Conclusion Our results indicate that fruit ingestion of four common African forest plant species positively affected germination capacity and mean germination time, and that recruitment success of these plant species may therefore largely depend on their seed dispersers.