Data from: Trait-associated loss of frugivores in fragmented forest does not affect seed removal rates

Seed dispersal by frugivorous animals forms the basis for regeneration of
numerous plant species. Habitat fragmentation has been found to be one
major factor perturbing frugivore communities and dependent plant species.
Yet, community-wide consequences of fragmentation for both frugivore and
plant communities are still hardly understood. Here, we studied the
effects of habitat fragmentation on the seed removal by frugivorous birds
and mammals from nine fleshy-fruited plant species in Białowieża Forest
(Eastern Poland). This last relict of old-growth lowland forest in Europe
poses an exceptional reference site for studying the impact of habitat
fragmentation on seed dispersal processes in temperate forest ecosystems.
In particular, (i) we tested for associations between forest fragmentation
and response traits of frugivores, that is forest specialization and body
mass; (ii) we studied the relationship between frugivore response and
effect traits, that is centrality (number of consumed plant species) and
interaction type (mutualistic vs. antagonistic); and (iii) we assessed the
feedback of fragmentation-induced changes on plant–frugivore interactions
and seed removal rates. We found that fragmentation led to shifts in the
frugivore community, associated with the response traits forest
specialization and body mass, with fewer forest specialists and
large-bodied frugivores in fragmented than in continuous forests. However,
forest generalists and small-bodied frugivores were more central in the
plant–frugivore associations than forest specialists and large-bodied
frugivores. Therefore, the loss of vulnerable species did not result in
reduced seed removal rates in fragmented compared with continuous forest.
Synthesis. These results indicate that seed removal may be relatively
robust in spite of shifts in the frugivore community in forest fragments.
The correlation between response and effect traits of frugivores
highlights the importance of forest generalists and small-bodied
frugivores for maintaining dispersal processes in fragmented forests in
temperate regions. Yet, future studies should aim at quantifying the
consequences of seed disperser loss on other aspects of dispersal, such as
long-distance dispersal, spatial patterns of seed deposition, seed
germination and plant regeneration.