Fruit tracking, frugivore satiation, and their consequences for seed dispersal
Langue
en
Article de revue
Ce document a été publié dans
Oecologia. 2008, vol. 156, n° 1, p. 137-145
Springer Verlag
Résumé en anglais
Vertebrate frugivore communities are easily satiated by abundant fruit supplies and, contrary to abiotic dispersal agents, typically disperse only part of the available seed pool. This frugivore satiation is likely to be ...Lire la suite >
Vertebrate frugivore communities are easily satiated by abundant fruit supplies and, contrary to abiotic dispersal agents, typically disperse only part of the available seed pool. This frugivore satiation is likely to be a widespread phenomenon and should be an influential predictor of plants’ ability to disperse their offspring to suitable establishment sites; yet it has never been systematically quantified. Here I investigate patterns of fruit abundance, frugivore activity and frugivore satiation, and their consequences for seed dispersal in the fleshy-fruited tree Frangula alnus. Based on constant-effort seed trapping conducted over 3 years, I assess densities of total and frugivore-consumed seedfall across two spatial (within/between populations) and two temporal (within/between ripening seasons) scales. Furthermore, I examine relationships between fruit abundance and the amount of seeds that are actually dispersed away from fruiting trees. Frugivore activity tightly matched fruit abundance, although some differences existed between scales. This marked fruit tracking did not prevent a significant frugivore satiation, however, and only 53% of the available fruit crops were actually consumed. The extent of satiation varied most at the within-population level, likely due to the territorial behaviour of important frugivore species. In contrast, levels of satiation remained remarkably invariable through time, suggesting that frugivores behave as opportunists and closely adjust the composition of their diet to the available food supply. Overall, greater fruit abundance resulted in a higher proportion of seeds falling beneath fruiting trees, but it also helped increase the (absolute) number of seeds dispersed. This study shows that frugivore satiation can be an important phenomenon even when frugivores tightly track fruit abundance. Its negative effects on recruitment may be attenuated, however, if greater fruit crops help increase population-wide frugivore activity and the amount of seeds being dispersed to suitable establishment sites.< Réduire
Mots clés
FRANGULA ALNUS
Mots clés en anglais
CROP SIZE
DISPERSAL LIMITATION
FRUGIVORY
RESOURCE TRACKING
SEED RAIN
FRUGIVORE
Origine
Importé de halUnités de recherche