Negative density dependence in the mortality and growth of tropical tree seedlings is strong, and primarily caused by fungal pathogens

Natural enemies have been implicated as agents of negative density dependence (NDD) in tropical forests, but their relative contributions to NDD, and thus the maintenance diversity, are largely unknown. We monitored rates survival growth on seedlings for 10 years moist forest Manu National Park, Peru. then experimentally manipulated plots exclude fungal pathogens, insects, small mammals large an additional 31 months assess influence these natural density-dependent interactions among seedlings. Fungal pathogens made most important contribution NDD. The application fungicide led lower mortality rates, faster decreased species diversity. Other taxa had at minor effects seedling performance. Synthesis. conclude that strongest contributors widely observed NDD occurs Moreover, presence augments diversity seedlings, indicating critical coexistence structure tree communities.