Effects of fragmentation and forest fires on seed-dispersal networks and the feedbacks on plant functional diversity

Abstract

Changes in vegetation resulting from natural tree mortality, deforestation or forest fires may alter local animal assemblages, favoring the colonization of forest edges by species associated with open habitats and reducing occupancy by forest specialists. Such changes in animal occupancy patterns may reshape animal-plant interaction networks such that certain interactions are lost while novel interactions are established. In forest edges or recently burned forests, for instance, seed-dispersal networks may lose interactions involving forest specialists such as primates and canopy birds and gain novel interactions among plants associated with open environments and generalist frugivores. The activity of habitat-generalist frugivores in disturbed areas may influence regeneration by favoring the dispersal of plant species associated with open habitats and more resistant to disturbance, helping those plants to colonize areas undergoing regeneration further into the forest. Because such plants are often drought (e.g., deep rooting) or fire- (thick bark) tolerant tree species, changes in dispersal patterns may reshape not only the taxonomic but also the functional composition of plant assemblages. Over time the replacement of plants that are less tolerant to disturbance by tolerant plants may alter vegetation structure, but increase forest resistance to disturbance. A few studies have investigated how landscape changes affect the structure of interaction networks but, the effects of disturbance on seed dispersal networks in the Amazon and how those changes feedback affecting forest regeneration and properties such as resistance and resilience are still unknown.