Seed dispersal by water, wind, birds, and bats in the Caliraya Watershed, Philippines
ID: 613 / 226
Proposed Symposium Title: Seed dispersal by water, wind, birds, and bats in the Caliraya Watershed, Philippines
Giancarlo Pocholo L. Enriquez, Lillian Jennifer V. Rodriguez
Affiliations: Institute of Biology, University of the Philippines Diliman, Quezon City, Philippines
Seed dispersal maintains genetic connectivity across fragmented landscapes and influences future vegetation assemblage. In the Philippines, only two seed dispersal studies have directly compared different seed dispersal agents. We investigated the seed dispersal patterns in the lowland secondary rainforest of the Caliraya Watershed, Laguna. In addition to bat, bird, and wind dispersal, we examined water dispersal and its relationship with the artificial Caliraya Lake. We compared the different dispersal agents and observed how forest characteristics influence seed dispersal. By running seed rain traps and conducting drift litter collection from March to June 2022, we collected and analyzed 14,090 seed rain seeds and 339 drift litter seeds in a 50-hectare privately owned land within the watershed. Water did not exclusively disperse any species and only acted as a secondary disperser. The 83-year young Caliraya Lake did not alter the vegetation to warrant adaptations to water dispersal. Seed density was significantly higher for bird-dispersed (n=166) and bat-dispersed (n=145) seeds than for wind-dispersed (n=79) seeds (One-way analysis of variance [ANOVA]: F2,87=16.21, P <0.0001). Species number was significantly higher for bird-dispersed (n=3.7) and bat-dispersed (n=3.9) than for wind-dispersed (n=0.2) seeds (One-way ANOVA: F2,87 = 16.67, P<0.0001). Birds were identified as the top dispersers, exclusively dispersing more species than bats, although they targeted different species and provided separate seed dispersal services. Birds were sensitive to forest characteristics, preferring forests with higher tree basal areas. Our results provide insights for future forest restoration efforts in the Caliraya Watershed or similar areas. We recommend a three-way approach to restoration efforts in the Caliraya Watershed: (1) ensure the presence of fleshy-fruited trees in restoration zones, (2) assist the establishment of mid-successional and wind-dispersed trees, and (3) tighten law enforcement and intensify conservation efforts.