Abstract booklet - gtö – Society for Tropical Ecology

198 SCIENTIFIC POSTER SESSION | FOYERSCIENTIFIC POSTER SESSION | FOYER199Topic: Biodiversity & economyTopic: The Andean biodiversity hotspot and its futureFOR FREE, STILL AVAILABLE - BUT THREATENED: THE ECONOMICCONTRIBUTION OF SAVANNA WOODLANDS TO RURALLIVELIHOODS IN NORTHERN BENINTHE VARIATION OF WOOD SPECIFIC GRAVITY AND ABOVEGROUNDBIOMASS ALONG GRADIENTS OF TOPOGRAPHY AND ELEVATION INTHE ANDES OF SOUTHERN ECUADORKatja Heubach 1 , Rüdiger Wittig 2 , Ernst-August Nuppenau 3 , Karen Hahn 2Jürgen Homeier 1 , Roman Link 11University of Göttingen, Göttingen, DE, jhomeie@gwdg.deWEDNESDAY | FOYER1BiK-F, Frankfurt, DE, katja.heubach@senckenberg.de, 2 Institute for Ecology,Evolution and Diversity, Goethe-University, Frankfurt, DE, 3 Institute for AgriculturalPolicy and Market Research, University Gießen, Gießen, DEAs provisioning ecosystem services of Westafrican savannas non-timber forestproducts (NTFPs) make a significant contribution to household income in ruralAfrican communities. Undertaking a livelihood approach focussing on multipurposeuseful plants our study aims to identify their respective share in ahousehold’s total income in order to elicit the strong interrelation betweenlocal natural resource use and livelihood maintenance. We interviewed a totalof 230 households across five different ethnic groups (Fulani, Ditammarie, Yom,Kabié and Bariba) in two villages in Northern Benin, Papatia and Chabi-Couma.Coevally, data on the economic value of the studied NTFPs was gathered byconducting market surveys as well as applying participatory rural appraisaltechniques. At present we are applying simple choice experiments due toinvestigate individual preferences concerning both direct use values andcultural / spiritual values of the studied plant species and ecosystem services,respectively. The results of the livelihood approach reveal the unquestionablyhigh economic importance of biodiversity provided by savannas: 39 % of ahousehold’s total income is generated by NTFPs. Up to now, this existential valueof savanna woodlands has been largely disregarded by local policy-makers andlandowners deciding whether to shift long-standing forest into agriculturalland or . Findings will be used to assist with appropriate decision making.Wood specic gravity (WSG) is a key plant functional trait and an importantvariable for aboveground tree biomass (AGB) and carbon stock estimation.Knowledge about spatial patterns of WSG and its environmental constraints intropical mountain forests is comparatively scarce, especially when it comes tothe efects of elevation and topography. Moreover, the answer to the question whethergradients in WSG infuence spatial patterns of AGB remains uncertain. In thisstudy, altitudinal and topographical gradients in AGB and WSG were assessedin a tropical mountain forest ecosystem in southern Ecuador. For this purpose, atotal of 1769 trees in 54 permanent sample plots along environmental gradientswere censused and WSG wasmeasured using a Pilodyn 6J wood tester. The obtained data were used toestimate AGB using allometric models from Chave et al. (2005) both withand without tree height as a predictive variable. WSG was found to increasesignicantly upslope by an average of 9,3 %, but did not show altitudinal gradients.If computed with tree height, AGB decreased signicantly both upslope and withelevation. AGB on lower slopes in the average was 95,8 % bigger than on upperslopes and decreased more than 1.5-fold with increasing altitude from a meanof 288.9 t/ha at approx. 1000 m a.s.l. to 112.3 t/ha at approx. 3000 m a.s.l.. Ifcomputed without tree height, AGB was found to be lowest at intermediateelevations, and AGB results were systematically higher.A possible explanation for the upslope decrease in WSG are reduced growthrates induced by nutrient limitation. The reason for the gradients in AGB ismost likely the altitudinal and upslope decrease in tree height in the study areawhich in former studies has been related to nutrient limitation as well. Giventhe enormous altitudinal decrease of tree height in tropical mountain forests,performance of allometric models which do not use tree height as a predictivevariable was found to be poor. The observed gradients in WSG could not predictthe patterns in AGB, in contrast, AGB was found to be highest in sites with lowWSG.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