Abstract booklet - gtö – Society for Tropical Ecology

148 PARALLEL SESSION HALL H III | ANTRHOPOGENIC INFLUENCESPARALLEL SESSION HALL H III | ANTHROPOGENIC INFLUENCES149Session: Anthropogenic influencesThursday, 24 February, 12:30, Hall H IVSession: Anthropogenic influencesThursday, 24 February, 12:45, Hall H IVBIRD DIVERSITY AND FEEDING GUILD COMPOSITION ALONG ATROPICAL FOREST-FARMLAND GRADIENT IN WESTERN KENYARonald Mulwa 1 , Katrin Böhning-Gaese 1 , Matthias Schleuning 11BiK-F Senckenberg, Frankfurt, DE, Ronald.Mulwa@senckenberg.deIMPACT OF ANTHROPOGENIC PRESSURE ON THE POPULATIONSTRUCTURE OF ANOGEISSUS LEIOCARPA WITHIN WARI-MAROFOREST RESERVE IN BENIN (WEST AFRICA)Achille Ephrem Assogbadjo 1THURSDAY 12:30 Hall H IVIn many tropical regions, forests have been replaced by secondary forests andfarmland habitats that often occur adjacent to remnants of near natural forest.Whereas numerous studies have investigated the effects of human disturbancein forest habitats, little is known about bird communities in tropical farmlands.We surveyed bird communities in Kakamega Forest and adjacent farmlands inwestern Kenya to assess variations in bird abundance, diversity and feedingguild composition across a habitat gradient during different seasons. Intwo types of forest (near natural vs. secondary forest) and farmland habitats(mixed and sugarcane farmland), we conducted point counts to record birdsand their key resources (i.e., fruits, flowers and invertebrates) over an entireyear. Bird abundances and resource availability fluctuated over the course ofthe year. Surprisingly, overall bird abundances were higher in farmland thanin forest habitats. Accordingly, flower, fruit and invertebrate availability werein higher farmland than in forest habitats, whereas the structural vegetationdiversity was higher in forest than in farmland habitats. However, feeding guildsof birds responded differently to differences between forest and farmlandhabitats. Frugivorous birds tended to be more numerous in farmland than inforest habitats, whereas insectivorous birds showed the opposite pattern. Thehigher frugivore richness in the farmland was directly related to the higherfruit availability in farmland than in forest habitats. Within forest and farmlandhabitats, bird species richness and abundance were higher in near naturalthan in secondary forest types and in mixed than in sugarcane farmland types,respectively. These differences might be due to the higher structural diversityin near natural forests and mixed farmlands, indicating that structurally diversehabitats support larger and more species-rich bird communities in both forestand farmland habitats. The differential response of different bird feeding guildsto tropical forest-farmland gradients indicates that conservation research oftropical bird communities should not rely on measures of overall bird diversity.1LEA-FSA-UAC, Cotonou, BJ, assogbadjo@yahoo.frThe present study focused on the analysis of the structure of the A. leiocarpadominated natural stands in the Wari-Maro forest reserve which are under highand minimal anthropogenic pressures. These stands were considered for forestinventory after carrying out a random sampling scheme of 40 sample units of30 m x 50 m. In each level pressure stand, the dbh and tree-height of identifiedtree-species were measured in each plot. Data analyses were based on thecomputation of structural parameters, establishment of the stem diameter andheight distributions and the floristic composition of the two types of stands.Results obtained showed higher values for the overall basal area, mean heightand diameter for A. leiocarpa presented in low-pressure stands. In the highpressurestands, the frequency of trees in the successive diameter classesdropped rapidly and the value of the logarithmic slope of the height-diameterrelationship was lower indicating a lanky shape. Results from the present studysuggest that effective conservation is needed for A. leiocarpa stands under highpressure by developing appropriate strategy for restoration purposes.THURSDAY 12:45 Hall H IVgtöSociety for Tropical Ecology | Gesellschaft für Tropenökologie e.V. Status and future of tropical biodiversity | Frankfurt, 21 - 24 February 2011gtö