Seed dispersal and frugivory : ecological consequences for tree populations and bird communities

In this thesis I investigated consequences of seed dispersal and frugivory for plant populations and bird communities. One aim was to determine the effect differences in frugivore diversity have on seed dispersal of focal plants and on the establishment of seedlings and trees. For that I compared the dispersal systems of two bird-dispersed tree species (genus Commiphora) at two sites with different frugivore diversity, i.e. in South Africa with a high avian frugivore diversity, and in Madagascar with a depauperate one. The results show that differences in frugivore diversity and behavior strongly affected seed dispersal, seedling establishment and the spatial distribution of seedlings and trees. In South Africa, high avian frugivore diversity lead to higher numbers of frugivores dispersing seeds, higher dispersal rates, seedling establishment away from trees and to a uniform tree distribution as compared to Madagascar. The influence of dispersal on the spatial pattern of tree populations was evaluated using a spatially explicit simulation model. A second aim of the thesis was to understand patterns of seasonality in fruit availability and its use by the frugivore community in South Africa. Fruit availability was highly seasonal with marked periods of fruit scarcity during the dry winter season and during the rainy season. Ficus trees occuring in high density, fruiting all-year and especially during general fruit scarcity, attracted most animals and are therefore considered as keystone resources in South African coastal forests. These results imply that the understanding of key processes such as seed dispersal and the knowledge of keystone resources is of crucial importance for conservation in a time of increasing biodiversity loss.

Grantor dc:publisher

Publikationsserver der RWTH Aachen University

Year dc:date

2000

Author dc:creator

• Bleher, Bärbel

Contributors dc:contributor

• Schuphan, Ingolf

• info:eu-repo/classification/ddc/570
• Biowissenschaften, Biologie
• Baum
• Populationsdynamik
• Samenverbreitung
• Vögel
• Tiergesellschaft

Statement dc:rights

• info:eu-repo/semantics/openAccess

Language dc:language

eng

Identifier

https://publications.rwth-aachen.de/search?p=id:%22RWTH-CONV-118365%22

OAI record oai:identifier

https://publications.rwth-aachen.de/oai2d?verb=GetRecord&metadataPrefix=oai_dc&identifier=oai%3Apublications.rwth-aachen.de%3A56248