Abstract booklet - gtö – Society for Tropical Ecology

230 SCIENTIFIC POSTER SESSION | FOYERSCIENTIFIC POSTER SESSION | FOYER231Topic: African savannas biodiversity - past, present, futureTopic: Ecological networks and ecosystem functioningHOW STRONG IS THE WEST AFRICAN SAVANNA VEGETATIONAFFECTED BY HUMAN LAND-USE? A COMPARISON BETWEEN APROTECTED AND A COMMUNAL AREABIODIVERSITY VS. SPECIES IDENTITY: ANT COMMUNITY EFFECTSON LEAF HERBIVORES AND SPIDER GUILDS IN INDONESIAN CACAOPLANTATIONSWEDNESDAY | FOYERKatharina Schumann 1 , Blandine Nacoulma 2 , Salifou Traoré 2 , AdjimaThiombiano 2 , Rüdiger Wittig 1 , Markus Bernhardt-Römermann 1 , KarenHahn 11Goethe University Frankfurt, Frankfurt am Main, DE, schumann@bio.unifrankfurt.de,2 University of Ouagadougou, Ouagadougou, BFNatural resources are particularly important for livelihood security in cash-poorhouseholds in semi-arid areas by ensuring food security, matching medicinalneeds and as a source of income. In recent years, natural resources are decliningdue to land-use intensification. Thus, there is an urgent need for sustainableland use practices. Analysing the impact of land-use on phytodiversity andvegetation can help to understand anthropogenic influences on naturalresource and to develop conservation and management strategies inaccordance with human needs. The aim of the presented study is to comparea protected versus a communal area concerning their vegetation compositionand phytodiversity. We studied if land-use has a specific effect on the vegetationcomposition and diversity pattern of vegetation types, which occur bothinside and outside the protected area. Vegetation relevés were performed inthe W National Park and its surrounding communal area in the eastern part ofBurkina Faso. Vegetation types were established using ordination (DCA) andclustering methods (k-means with subsequent bootstrapping). For each ofthese types, typical species were detected using an indicator species analyses.Furthermore, we tested the effect of land-use on species richness, evenness,life form composition and ecosystem structure (cover and height) for the herband woody layer. Our results reveal five vegetation types all occurring in theprotected and the communal area. The impact of land-use on phytodiversitywas vegetation type specific. However, for the woody layer species richnessand evenness showed a more homogenous distribution in the communal areacompared to the protected area. The opposite was observed for the herb layervegetation. In addition, ecosystem structure and life form composition werealso affected by land-use. We conclude that land-use has a certain impact onthe vegetation. However, the vegetation differs more between the vegetationtypes than between the protected and communal area.Hannes Seidel 1 , E. Efendi 2 , Arno Wielgoss 3 , Yann Clough 31Uni Göttingen/Würzburg, Obernbreit, DE, hannesseidel@gmx.de, 2 TadulakoUniversity, Palu, ID, 3 Georg-August-Universität, Göttingen, DEUnderstanding herbivore-plant and predator-prey interactions or competitionwithin a trophic level is essential to help maintain agricultural production. Antsand spiders are among the most abundant terrestrial predators in natural andagricultural habitats. Both groups may have negative impacts on importantinsect pests of cacao. Because of the unclear influence of ant diversity andactivity on herbivore insects and spiders, we investigated how ant communitiesaffect herbivory and the presence of spiders. And we tested whether the overallpredation services of complex ant communities are higher than those ofsingle, aggressive dolichoderine ant species known to have high impacts onherbivores. We surveyed arthropod communities and measured leaf area loss incacao plantations in Sulawesi between July and September 2010. Observationswere carried out within a large scale and long term ant fauna manipulationexperiment. We sampled trees in 16 cacao plots situated in plantationsdiffering in habitat characteristics, e.g. shade cover and distance to the nearestrain forest. Each plot consisted of four subplots, nine trees each, subjected todifferent treatments performed since August 2009: 1) control 2) ant exclusion3) establishment of Philidris cf. cordata and 4) establishment of Dolichoderusthoracicus within the cacao trees in order to create single species dominated antcommunities. Three trees per subplot were chosen to estimate herbivory andabundance of herbivores and spiders, twice during the study period. To assessherbivory we collected twenty fully developed leaves per tree using stratifiedrandom sampling. The abundance of herbivores and spiders was evaluated byinspecting trees visually. Spiders were classified into guilds according to theirhunting strategies. The influence of ants in general and of Philidris cf. cordata.and Dolichoderus thoracicus in particular on herbivory, herbivore density andcomposition, as well as on spider density is analysed using linear mixed models.Wednesday WEDNESDAY 16:00 | FOYER | FoyergtöSociety for Tropical Ecology | Gesellschaft für Tropenökologie e.V. Status and future of tropical biodiversity | Frankfurt, 21 - 24 February 2011gtö