Interactions among Frugivores and Fleshy Fruit Trees in a Philippine Submontane Rainforest

Abstract: We assessed the potential effect of frugivore extinctions on forest regeneration in the North Negros Forest Reserve, a forest fragment that is one of the last remaining wet tropical rainforest ecosystems in the biogeographic region of the central Philippine Islands. We evaluated foraging observations of 19 species of birds, fruit bats, and other mammals in three successional habitats and identified tree species that are potentially at risk because their seeds are dispersed by frugivores that are seriously endangered. The relative abundance of zoochorous trees in this forest community was exceptionally high (80%), suggesting that the process of forest regeneration will change drastically if endangered frugivores are hunted to extinction. We grouped 45 tree species as early-, mid-, or late-successional species based on their population structure and we demonstrated that early-successional tree species were visited by a wide spectrum of frugivores, whereas mid- and late-successional species were visited mostly by hornbills (Bucerotidae) and fruit pigeons (Columbidae). Late-successional tree species were most specialized with respect to dispersers and could therefore be susceptible to extinction. We recommend tree species that could be useful for assisted natural regeneration projects in the reserve because they are visited by a variety of frugivores. Of those, we recommend early-successional trees for open-field plantations and mid-successional tree species for enrichment plantings.