Exploring top-down control: an exclusion experiment in early stage of dipterocarp reforestation plots

Abstract The early stage of seedling establishment is critical to successful ecological restoration and reforestation, and it is partially influenced by herbivory. Aerial vertebrate predators, including birds and bats, can affect plant growth by controlling phytophagous insects. This study explored the effects of excluding birds and bats on the arthropod community during the initial stages of reforestation plots planted with Dipterocarpus alatus in deciduous dipterocarp forest using an exclusion experiment. We hypothesized that birds and bats negatively affect the density and biomass of large-sized arthropods (≥ 1 cm), which are their potential prey, and that excluding these predators may affect seedling growth and leaf damage. The density and biomass of large arthropods significantly increased in the permanent exclosures compared to the control group. No significant difference between the nocturnal and diurnal exclosures was observed. Top-down effects on the biomass of large-sized phytophagous and predatory arthropods were pronounced during the dry season, coinciding with the presence of migratory insectivorous birds. Mesopredator release primarily driven by ants compensated for the absence of birds and bats, preventing immediate increases in herbivory or impacts on seedling growth. These findings highlight the importance of ecological redundancy among predator communities in maintaining herbivory control. Promoting diverse habitats that support both invertebrate and vertebrate predators may enhance the long-term resilience and effectiveness of pest control in ecological restoration efforts.