| dc.description.abstract | The last decades have seen a biodiversity in many tropical rainforests decline leading to a
species-extinction crisis. Loss of biodiversity might, for example, alter the composition of
frugivore assemblages in fruiting trees and lead to a breakdown in seed dispersal.
Disrupted seed dispersal could have long-term consequences for forest regeneration and
might be a serious threat to tropical plant diversity (da Silva and Tabarelli, 2000).
The main objective of this study was to establish the effect of forest fragmentation and
the type of management on avian frugivores and consequences for seed dispersal and
plant regeneration processes. The study focused on the influence of forest fragmentation
and disturbance on avian frugivores feeding on Ficus thonningii fruits and seedling
establishment of animal dispersed trees below the crowns of F. thonningii in Kakamega
Forest, Western Kenya. Individual F. thonningii trees with ripe fruits were selected in
continuous forest, fragments and sites under Forestry Department (FD) and Kenya
Wildlife Service (KWS). Seed traps under the same trees provided data on seed
deposition by avian visitors and systematic seedling mapping provided data on
recruitment under F. thonningii trees. Standardised tree observations were carried out and
all avian frugivore visitors were quantified. During 400 observation-hours 29 frugivorous
bird species visiting F. thonningii wer"e recorded. Forest specialist frugivore species
declined significantly both in the fragments and FD managed sites as compared to
continuous forest and KWS managed sites. Frugivores made significantly shorter visits in
trees located in low disturbance sI.tes. Furthermore, the number of frugivores visiting a
tree had a significant effect on the number of seeds collected below the crowns of F.
thonningii trees. This study shows that fragmentation and disturbance leads to a decrease
in the number offrugivores and especially the forest specialist species. However, this loss
does not seem to have any impact on seedling establishmenj on the short-term since more
seedlings were found establishing in the fragments (1.3 seedlings/nr') than in the
continuous forest (0.45 seedlings/m") (t-tests p < 0.05). Whether this has implications on
the long-term regeneration of our forests r.equire more detailed and long-term studies. In
the short term, however, management needs to be improved especially in the FD
managed sites. | en |
