Retaining fruiting trees in the agricultural matrix is important for bird-mediated seed dispersal in a fragmented forest landscape

Abstract

Birds are one of the most important seed dispersers of trees in tropical forests. However, forest loss and fragmentation due to anthropogenic land-use changes are affecting bird communities and movement, which can alter their seed dispersal services. To estimate the importance of birds in forest regeneration, we created a spatially explicit individual-based model (IBM) that simulates bird-mediated seed dispersal, specifically in the context of a fragmented forest landscape. We used movement data of a Spotted Imperial Pigeon (Ducula carola), one of the largest frugivore in our study site in Northeast Luzon, Philippines, and captive feeding experiments to inform our movement model and seed retention times, respectively. Our seed dispersal IBM predicted that the pigeons contribute to frequent short distance and occasional long distance seed dispersal, able to move between forest patches. We also simulated the removal of fruiting trees in the agricultural matrix, and it led to decreased number of seeds dispersed, less trees visited, less feeding events by birds, and a smaller area covered by seed dispersal. Hence, remnant trees should be preserved as they have the potential to promote natural forest regeneration. This IBM serves as a versatile tool for researchers and decision-makers, contributing evidence for scaling decision-making on the wider adoption of trees in rural landscapes.