Effect of hunting pressure and forest fragmentation on seed dispersal of Staudtia kamerunensis (Myristicaceae) in the Western Congolian forest-savanna mosaic

Numerous studies have investigated the impact of hunting and forest fragmentation on seed dispersal processes, but few of them in Africa. The African continent, however, holds the greatest abundance of large frugivores on Earth and is subject to increasing levels of hunting and forest fragmentation. Frugivory and seed dispersal in the pan-tropical family Myristicaceae has been well studied in the Neotropics, but remain barely known in Afro-tropical forests. Here we investigated how hunting, forest cover, and fruit availability influence the dispersal capacities of Staudtia kamerunensis in a mosaic composed of forest patches and savannas in D.R. Congo. We selected 34 fertile female S. kamerunensis trees distributed, at a landscape scale (300 km²), across 5 sites characterized by a gradient of hunting pressures and density of the study trees. The trees varied in size and surrounding forest cover (patch and corridors). We quantified the percentages of seed dispersal failure using litter trap and fruit remains during the entire 2013 fruiting season, and identified fruit eaters through focal observations. The most frequently observed frugivore was the White-thighed Hornbill (Bycanistes albotibialis). Our GLMM analyses show that increasing hunting pressure, decreasing abundance of B. albotibialis and decreasing forest cover near focal trees significantly increased dispersal failure. The limited forest cover of some patches, resulting from the highly fragmented feature of the landscape, and hunting pressure, are likely to impact negatively the abundance of B. albotibialis. Consequently, we suggest the dispersal system reached saturation because of a lack of effective seed dispersal away from parent trees.