Theoretical and Empirical Foundations for a Seed Dispersal Network Model Linking Plant Reproductive Success to Wildlife Defaunation in Nigerian Rainforests

Defaunation of large-bodied seed dispersers from Nigerian rainforests through bushmeat hunting is predicted to impair the seed dispersal of large-seeded trees, with long-term consequences for forest regeneration and composition, yet no mechanistic dispersal network model calibrated to Nigerian rainforest conditions exists to quantify these effects. This study develops an original seed dispersal network model linking plant reproductive success to wildlife defaunation in Cross River and Ondo State rainforests, and tests the model empirically against measured seed dispersal outcomes across a hunting intensity gradient. The theoretical model integrates mutualistic network theory, optimal foraging theory, and plant demography to generate predictions about the consequences of disperser loss for seed dispersal quality, post-dispersal seed fate, and long-term plant recruitment. Empirically, seed dispersal networks were characterised at six study sites ranging from heavily hunted to lightly hunted forest, through camera trapping (totalling 8,400 trap-nights), seed rain traps (20 traps per site for 12 months), seed fate experiments, and seedling establishment monitoring. Network metrics including linkage density, connectance, interaction evenness, and species vulnerability to partner loss were computed. Results confirmed that disperser richness and visitation rates declined significantly with hunting intensity (r = -0.84, p < 0.01). Large-seeded species (seed mass greater than 5g) experienced the steepest dispersal quality declines in heavily hunted sites. Seed shadow breadth contracted by 67% at heavily hunted sites relative to lightly hunted ones. Network vulnerability analysis identified 12 large-seeded tree species at risk of regeneration failure, including Panda oleosa and Lovoa trichilioides. The study provides the first quantitative seed dispersal network model for Nigerian rainforest and makes an original contribution to the defaunation-plant demography interface in West African ecology. Keywords: seed dispersal network, defaunation, bushmeat hunting, rainforest regeneration, Cross River