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

Forest fragmentation and habitat loss are major disruptors of
plant–frugivore interactions, affecting seed dispersal and altering
recruitment patterns of tree species dependent on vertebrate dispersers.
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 h). Frugivore composition differed among the four tree
species with the large-seeded Canarium
strictum and Myristica dactyloides exclusively
dependent on large-bodied avian frugivores,
whereas, medium-seeded Persea
macrantha and Heynea trijuga were
predominantlyvisited by small-bodied and
large-bodied avian frugivores,
respectively. Using the seed-dispersal-effectiveness
framework, we identified effective frugivores and examined their response
to forest cover and fruit crop size. Results were idiosyncratic and
governed by plant and frugivore traits. Visitations to
medium-seeded Persea had a positive relationship with
forest cover but the relationship was negative for the
large-seeded Myristica. In addition, two of the three
effective frugivores for Persea responded to the interactive effect of forest cover and fruit crop size. Frugivore visitations to Hyenea were not related to forest cover or fruit crop and there were too few visitations to Canarium to discern any trends. These results highlight the context-specific response of plant-frugivore interactions to forest cover and fruit crop size influenced by the plant and frugivore traits.