Forest cover and fruit crop size differentially influence frugivory of select rainforest tree species in Western Ghats, India

摘要

Forest fragmentation and habitat loss are major disruptors of plant-frugivore interactions, affecting seed dispersal and altering recruitment patterns of the dependent tree species. In a heterogeneous production landscape (primarily tea and coffee plantations) in the southern Western Ghats, India, we examined effects of surrounding forest cover and fruit crop size on frugivory of four rainforest bird-dispersed tree species (N = 131 trees, >= 30 trees per species, observed for 623 hr). Frugivore composition differed among the four tree species with the large-seededCanarium strictumandMyristica dactyloidesbeing exclusively dependent on large-bodied avian frugivores, whereas medium-seededPersea macranthaandHeynea trijugawere predominantly visited by small-bodied and large-bodied avian frugivores, respectively. Using the seed-dispersal-effectiveness framework, we identified effective frugivores and examined their responses to forest cover and fruit crop size. Results were idiosyncratic and were governed by plant and frugivore traits. Visitations to medium-seededPerseahad a positive relationship with forest cover but the relationship was negative for the large-seededMyristica. In addition, two of the three effective frugivores forPersearesponded to the interactive effect of forest cover and fruit crop size.Frugivore visitations toHeyneawere not related to forest cover or fruit crop, and there were too few visitations toCanariumto discern any trends.These results highlight the context-specific responses of plant-frugivore interactions to forest cover and fruit crop size influenced by plant and frugivore traits.