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Differences in frugivores affect consumption of fruits and seed dispersal in tropical forests

Frugivory and seed dispersal are key processes that shape both plant and animal communities, and are important in the maintenance and regeneration of forest ecosystems threatened by environmental changes.

Previous studies on frugivory and seed dispersal have relied on direct observations and fruit-fall traps. However, the presence of human observers and traps may deter some large frugivores from feeding sites, and may also result in bias against detection of some types of frugivores.

In a study published in Global Ecology & Conservation, researchers used camera trapping in Chinese (Xishuangbanna) and Thai (Mo Singto) tropical forest plots to determine frugivores and potential seed dispersers of a large-seeded tree species, Baccaurea ramiflora, a semi-evergreen species.

The two plots differ in their mammal faunas, with more large species (Asian elephant, white-handed gibbon, bears) surviving on the Mo Singto plot.

The researchers sought to determine whether the differences in frugivores, especially mammal faunas, between the Chinese and Thai plots could affect the consumption of fruits and dispersal of seeds on the respective plots, and hence the possible survival of the tree species.

Based on the relative number of fruits consumed, they identified M. leonina as potentially the most important disperser of B. ramiflora in the two forest plots. Fruit abundance consistently influenced frugivore activity (visitation and consumption).

They further found that visitation and consumption parameters varied between the two plots, which may be explained by differences in their animal communities.

In Mo Singto, where more large frugivores remain, B. ramiflora seeds could be potentially dispersed over longer distances. Conversely, in Xishuangbanna, where most large frugivores have already been lost, large-seeded species will be dispersed over shorter distances.

"This study suggests potential consequences of anthropogenic change (chiefly habitat degradation and hunting) on the fate of large-seeded plants," said Supparat Tongkok, a Thai student pursuing M.Sc. studies at Xishuangbanna Tropical Botanical Garden (XTBG).