Partial recovery of large seed arrival following ecological restoration in fragmented tropical rainforests

Forest restoration success depends crucially on the reinitiation of ecological processes such as seed arrival that drive natural regeneration. We know little about whether, by increasing and diversifying local seed sources to alleviate seed limitation, and attracting animal frugivores to alleviate dispersal limitation, restoration could shift seed arrival rates and species composition in the direction of mature rainforests, particularly for large‐seeded species in degraded fragments. We tested this by examining seed arrival over a year in 189 1‐m 2 seed fall traps within 63 seed trapping stations across sites ecologically restored (through maximum diversity mixed‐native species planting 13–21 years ago) and those left unrestored within degraded rainforests fragments, and in mature ‘benchmark' rainforests, in India's Western Ghats. We found that overall, large‐seeded species arrival rates in restored sites was comparable with benchmark, and was higher than unrestored sites. Seeds arriving through dispersal (from fruiting trees absent in the overstory) also showed a recovery towards benchmark levels, but were dominated by alien species abundant in the matrix habitat. Restoration also had no effect on species richness and composition of all arriving seeds, with restored sites closely resembling unrestored sites and remaining distinct from benchmark sites. Further, restoration did not alleviate the effect of fragment isolation on large seed arrival rates, which declined with distance from benchmark forests similarly in restored and unrestored sites. Our results suggest that restoration can increase local availability and dispersal of large seeds, and highlights the value of diverse native species restoration plantings within degraded forests and promoting their use instead of alien tree species in the surrounding matrix. However, our findings also show that recovery of natural regeneration can remain slow or uncertain in restored forest fragments, and underscore the need for sustained monitoring and evaluation of restoration over multiple decades.