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When non‐native species invade ecosystems, coevolved plant–animal interactions and associated ecological functions are altered, often to the detriment of local biodiversity. While mutualistic interactions can benefit from—and assist with—ecological restoration through the removal of non‐native species, community‐level changes in antagonistic interactions due to restoration are less well understood. Insect seed predators provide important ecosystem functions, but can also have antagonistic effects through pre‐dispersal seed predation which can cause fruit abortion or premature fruit drop, potentially affecting plant community composition.Here, we used a network approach and data on trophic interactions from a large‐scale field experiment to investigate the differences in insect seed predator communities between native restored sites (where non‐native plants were removed) and unrestored sites dominated by non‐native plants on the island of Mahé, Seychelles.Restored sites contained more individuals and species of seed predators (up by 81% and 50% respectively), and experienced a greater predation intensity (1.06 ± 0.53 vs. 0.27 ± 0.09), and predator specialisation compared to unrestored sites. The proportion of predated samples was similar between treatments (~14%). Beta diversity, measured as species and interaction turnover, increased at restored sites.Synthesis and applications: Our findings imply that vegetation restoration generates marked biodiversity benefits on native seed predator communities and their interactions. However, removing non‐native plants did not result in the elimination of non‐native seed predators, which might require targeted control measures. Our results highlight the importance of considering the effects of restoration on antagonistic interactions, in addition to those reported for pollination and seed dispersal services. Management practices should aim to control plant invasions for the conservation of native plant communities that serve as resources and refugia both for mutualists (e.g., seed dispersers and pollinators) and native insect seed‐predator antagonists, both of which benefit native ecosystem function. [ABSTRACT FROM AUTHOR]

Invasive non‐native species can alter animal‐mediated seed dispersal interactions and ultimately affect the stability of recipient communities. The degree of such disturbances, however, is highly variable and depends on several factors, two of which have received little attention: the relative timing of native and non‐native fruiting phenologies, and the associated variation in relative resource availability across the fruiting period. Both are likely to alter plant–seed disperser interactions threatened by biological invasions.Here we investigated the impact of plant invasions on the seasonal dynamics of frugivory and seed dispersal networks across a large‐scale experimental setup and a plant invasion gradient on a tropical island. We recorded fruit and frugivore abundances, and plant–frugivore interactions across eight inselbergs (i.e. rocky outcrops) with different levels of plant invasion during 10 months on the island of Mahé, Seychelles. By combining four sampling methods of plant–frugivore interactions we constructed quantitative seed dispersal networks at all sites across two 5‐month seasons: the on‐peak and off‐peak fruiting season.Our findings showed that, by fruiting mostly synchronously with natives, non‐native plants compete with natives for dispersal services, predominantly carried out by native frugivores. Variation in native seed dispersal was driven by plant invasion and seasonality. Specifically, native seed dispersal declined with the degree of invasion; dispersal frequency increased with fruit abundance more strongly during the off‐peak fruiting season; and networks became increasingly specialised during off‐peak. These results indicated that during the main fruiting peak seed dispersal services were saturated, which likely intensified the competition between native and non‐native fruits. When resources were scarce during off‐peak fruiting season, native and non‐native frugivores were more selective in their fruit choice at sites dominated by non‐native plants.We showed that native plant and frugivore populations and native seed dispersal interactions were more vulnerable in invaded plant communities, where non‐native plants compete with natives for dispersal services potentially reducing native recruitment. As invasive non‐native plants dominate many ecosystems world‐wide, particularly on islands, our findings showed that controlling plant invasions in vulnerable native communities can be critical to maintain native ecosystem functions and biodiversity. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

Forest remnants often act as refuges for native plant species within a degraded and highly fragmented forest matrix. Understanding whether these native patches can function as feeding grounds for frugivores and seed sources for native plant dispersal into the surrounding forest can provide critical information on ecosystem functions on a landscape scale and guidance on forest restoration. We used a large‐scale natural system of eight granitic inselbergs in the Seychelles and recorded the identity and transport direction of seeds retrieved from the droppings of mist‐netted birds across an invasion gradient. We found that inselberg forest remnants are important feeding areas for frugivores, acting as a source of native propagules to the surrounding invaded forests and potentially limiting the progression of non‐native plant invasion. Two dominant non‐native plant species (Cinnamomum verum and Clidemia hirta) were highly integrated into the frugivores' diets, competing with native plants for dispersal services. Despite the high non‐native propagule pressure, the spill‐over effect of native seeds into the invaded forest seemed to have a more durable positive effect on native plant recruitment fading out with distance to the inselberg edge. Our findings illustrate that remnant forest patches can generate positive spill‐over of native seeds into degraded surrounding forests through directed seed transport by frugivores. This cross‐boundary transport may slow down plant invasion and contribute to the recovery of adjacent degraded ecosystems. Forest remnants and avian frugivores therefore play a key role in the maintenance of native biodiversity and act as insurance for future restoration efforts. [ABSTRACT FROM AUTHOR]