Seed Dispersal Services by Frugivorous Birds in Tropical Forest Regeneration Following Selective Logging

Abstract

Selective logging alters forest structure and can disrupt even the most critical ecosystem processes, such as seed dispersal, which is critical for natural regeneration. This is an evaluation of frugivorous bird seed dispersal and regeneration of tropical forests that have been selectively logged. The field experiment compared logged and unlogged control sites over 12 months, including bird surveys, seed rain sampling, and a germination experiment. One thousand two hundred and forty-eight observations of birds were made to constitute 37 frugivorous species, and the richness of species decreased by a quarter in the logged regions. Nevertheless, seed dispersal was also high: frugivorous birds scattered an average of 18,600 seeds per hectare per year in logged forests, compared with 24,300 in unlogged areas (a 23% reduction). It is interesting to note that the medium- and large-bodied birds together accounted for approximately 86% of total seed dispersal, highlighting their dominant role despite a 31% decline in abundance post-logging. The distribution of seed deposition showed a higher percentage (46%) of early-successional plant species in the logged regions than in the controls (28%). The success of seed germination of the dispersed seeds (bird-favored) was found to be much better (by 17%, p < 0.05) as compared to the non-dispersed. The findings show that, despite selective logging decreasing bird diversity and dispersal rates, frugivorous birds remain an important part of the forest regeneration process by driving seed flow and facilitating plant growth. The conservation plans must prioritize safeguarding important frugivore species and the habitat structures that facilitate their survival. The further increase in the structural complexity of logged forests could also enhance seed dispersal services and accelerate the restoration of the ecosystem.