Restoration legacy, forest cover and elevation shape frugivory in a tropical landscape

Abstract

Assisted and passive natural restoration are widely applied strategies for forest restoration, yet their focus on tree recovery makes their effectiveness in restoring broader biodiversity unclear. Assuming that tree recruitment will rebuild whole ecosystems overlooks other taxa and their interactions, and thus underestimates key components of biodiversity like biotic interactions. To address this gap, we assessed two complementary questions: (i) how frugivory reestablishes and varies among assisted restoration and natural regeneration areas, and (ii) how local conditions (fruit availability, elevation, and time since restoration) and landscape context (forest cover and fragmentation) influence frugivory beyond restoration strategies. This was done by implementing a dummy fruit experiment in a tropical landscape in southeast Ecuador that considered two fruit sizes. Dummy fruit handling did not differ between assisted and naturally regenerated areas, indicating that neither restoration strategy was superior in promoting frugivory. Instead, landscape context played a central role. Fruit handling increased with old-growth forest cover and elevation, and declined with increasing forest fragmentation, highlighting the importance of habitat amount and connectivity for interaction recovery. Fruit size further shaped frugivory patterns, particularly in restored areas, where larger fruits were handled more frequently. Overall, our results show that restoration outcomes for frugivory depend less on restoration strategy alone and more on landscape structure and environmental context. By demonstrating the utility of artificial fruits as a rapid and practical tool to assess interaction recovery, this study highlights the need to move beyond vegetation-based metrics and explicitly incorporate biotic interactions into the evaluation of forest restoration success.