Are fragments fruitful? A comparison of plant–seed disperser communities between fragments and contiguous forest in north‐east India

Abstract

AbstractPlant–seed disperser interactions are critical for maintaining tropical plant diversity. However, these interactions are altered by habitat fragmentation, a pervasive threat to the tropics globally. We compared vegetation structure, richness and composition of plant–avian seed disperser interactions across two forest fragments (area: ~25 km2), and one contiguous forest site in the last remaining lowland tropical forests in north‐east India. We used network‐level indices (nestedness, generality, and vulnerability) and species‐level indices (degree and species strength) to identify key plant and bird groups across the three sites. We found that the three sites varied in habitat structure and were more similar in the composition of avian seed dispersers than plants. The low similarity in plant‐seed disperser interactions between the three sites was likely influenced by low similarity in fruiting plants. The fragmented sites exhibited fewer pairwise interactions and were characterized by a higher representation of small‐seeded plants, climbers, and open‐forest birds. Small‐bodied birds (bulbuls and barbets) played a central role in all the seed dispersal networks, while large‐bodied birds (hornbills) performed persistent interactions with large‐seeded plants at all sites. This is one of the first studies from the Asian tropics to investigate the differences in the plant–avian seed disperser communities between forest fragments and contiguous forest. Our findings highlight the conservation value of fragments given their potential to hold a distinct set of plant–seed disperser interactions, thereby maintaining functional diversity in fragmented tropical landscapes.Abstract in Hindi is available with online material.