Abstract booklet - gtö – Society for Tropical Ecology

144 PARALLEL SESSION HALL H IV | ANTRHOPOGENIC INFLUENCESPARALLEL SESSION HALL H IV | ANTHROPOGENIC INFLUENCES145PARALLEL SESSION: THURSDAY, 24 FEBRUARY, 11:30, HALL H IVANTHROPOGENIC INFLUENCESChair: Doyle McKeySession: Anthropogenic influencesThursday, 24 February, 11:45, Hall H IVFOREST REGENERATION DYNAMICS IN DIFFERENTLY MODIFIEDSOUTH AFRICAN SCARP FORESTSAlexandra Botzat 11University of Marburg, Marburg, DE, botzat@staff.uni-marburg.deTHURSDAY 11:30 Hall H IVRESILIENCE OF ECOLOGICAL SERVICES IN HUMAN MODIFIEDFOREST TYPES IN SOUTH AFRICAEike Lena Neuschulz 1 , Nina Farwig 11University of Marburg, Marburg, DE, neuschulz@staff.uni-marburg.deHuman disturbance is a major threat to forest ecosystems modifying speciesdiversity, community composition and ecological services. Local changes ininsect and bird communities can affect pollination and seed removal whichfinally, may influence the persistence of plant populations. We investigated theeffects of forest modification on insect and bird communities in South Africaand studied pollination and seed removal of the tree species Celtis africana. Wechose six representative types of forest modification, influenced by differentintensities of human disturbance. Species’ abundance and composition ofinsect and bird communities differed significantly among the different foresttypes. Specialized forest birds strongly declined with increasing habitatmodification, whereas generalist bird species and insect richness increased inmore modified forest types. We found enhanced pollination and seed removalof C. africana in modified forests compared to natural forest types. These resultsindicate that the mobility of insects and birds seems to maintain pollination andseed removal even in isolated forests and implies resilience of these ecologicalservices to habitat modification.Human disturbance imperils biodiversity and ecological processes involvedin forest regeneration, such as seed fate and seedling recruitment. Weconducted seed fate experiments and determined species richness, abundanceand composition of small mammals, adult trees, seedlings and saplings infive representative types of South African scarp forest, including naturalforest, differently modified fragments and secondary forest. Seeds werepredominantly consumed by small mammals and not secondarily dispersed.Seed predation was highest in highly modified forest types, although werecorded no differences in species richness and abundance of small mammals.However, high species turnover indicated variations in species composition,which explain the differences in seed predation pressure. For trees we foundlower richness, abundance and recruitment in highly modified forest types, aswell as a shift in community composition towards early successional species.These findings indicate less forest regeneration potential in highly modifiedforest types and thereby suggest that isolated forest fragments and secondaryforest act as population sinks in forest regeneration dynamics.THURSDAY 11:45 Hall H IVgtöSociety for Tropical Ecology | Gesellschaft für Tropenökologie e.V. Status and future of tropical biodiversity | Frankfurt, 21 - 24 February 2011gtö