Abstract booklet - gtö – Society for Tropical Ecology

108 PARALLEL SESSION HALL H IV | PLANT PHYSIOLOGYPLENARY KEYNOTE HALL | H III | WEDNESDAY 109Session: Plant PhysiologyWednesday, 23 February, 12:15, Hall H IVKeynote speaker: Meike Piepenbring; Chair: Gerhard KostWEDNESDAY 12:15 Hall H IVCHANGE IN HYDRAULIC PROPERTIES AND LEAF TRAITS OF ATALL RAINFOREST TREE SPECIES SUBJECTED TO LONG-TERMTHROUGHFALL EXCLUSION IN THE PERHUMID TROPICSBernhard Schuldt 1 , Christoph Leuschner 1 , Viviana Horna 1 , GeraldMoser 2 , Michael Köhler 3 , Henry Barus 41University of Goettingen, Goettingen, DE, info@plant-ecology.de, 2 Plant Ecology,Gießen, DE, 3 Tropical Silviculture and Forest Ecology, Goettingen, DE, 4 Departmentof Agrotechnology, Palu, IDIn a throughfall displacement experiment on Sulawesi, Indonesia, three 0.16ha stands of a premontane perhumid rainforest were exposed to a two-yearsoil desiccation period that reduced the soil moisture in the upper soil layersbeyond the conventional wilting point. About 25 variables, including leafmorphological and chemical traits, stem diameter growth and hydraulicproperties of the xylem in the trunk and terminal twigs, were investigated intrees of the tall-growing tree species Castanopsis acuminatissima (Fagaceae)by comparing desiccated roof plots with nearby control plots. We tested thehypotheses that this tall and productive species is particularly sensitive todrought, and the exposed upper sun canopy is more affected than the shadecanopy. Hydraulic conductivity in the xylem of terminal twigs normalised tovessel lumen area was reduced by 25 %, leaf area-specific conductivity by 10-33 % during the desiccation treatment. Surprisingly, the leaves present at theend of the drought treatment were significantly larger, but not smaller in theroof plots, though reduced in number (about 30 % less leaves per unit of twigsapwood area), which points to a drought effect on the leaf bud formationwhile the remaining leaves may have profited from a surplus of water. Meanvessel diameter and axial conductivity in the outermost xylem of the trunk weresignificantly reduced and wood density increased, while annual stem diameterincrement decreased by 26 %. In contradiction to our hypotheses, (i) we foundno signs of major damage to the C. acuminatissima trees nor to any otherdrought sensitivity of tall trees, and (ii) the exposed upper canopy was not moredrought susceptible than the shade canopy.TROPICAL MYCOLOGY – IN AN INFINITE PIONEER STATE?Meike Piepenbring, Universität Frankfurt aM, Frankfurt am Main, DE,piepenbring@bio.uni-frankfurt.deFungi are mostly microorganisms, omnipresent and indispensable in ecosystems asdecomposers of organic material, mycorrhizal symbionts, food for animals, parasitescontributing to the diversity of plants and animals, as well as lichenized pioneerorganisms colonizing sterile substrates. We appreciate them as food and in foodtechnology, as source of medicine, other active compounds, for bioremediation,biological control, and many other aspects. Fungi are feared as agents of diseasesin humans, animals, and cultivated plants, as moulds in buildings and on otherartefacts. We know about 100,000 species, i.e. about 6.7 % of 1,5 millions of speciesestimated to exist worldwide. For tropical countries, we probably know less than 5 %of the fungi existing there. Fungi are highly diverse morphologically, ecologically, andsystematically, with species of numerous different phylogenetic lineages developingfruiting structures of any imaginable form and interacting with maybe any organismon earth. Especially for tropical fungi, however, we ignore host specificity of manygroups of parasitic fungi, important aspects of life cycles, adaptations to tropicalseasons, interactions with other organisms, and phylogenetic relationships especiallyof not cultivable microfungi.We do not really know the status of tropical fungal diversity because tropicalmycology is still in a pioneer phase due to historical reasons, tropical climate, andonly a small number of fungal taxonomists working in the tropics. The identificationof most tropical fungi is very difficult, because numerous species of tropical fungi areincompletely described, monographs are lacking, type specimens are inaccessibleor incomplete, and because of administrative constraints. If classical mycologicalresearch continues with the current rate of descriptions of new species, we needmore than 1,000 years to document all the missing fungal species. Sequencedata taken from soil and plant organs indicate the presence of numerous, maybeunknown fungal species. Sequence data without the fungal organism, however, donot promote taxonomical knowledge because without morphology, it is not possibleto formally describe new species, and comparative molecular data of morphologicallydescribed species are lacking for many groups of tropical fungi. Meanwhile, tropicalprimary vegetation is destroyed and species of fungi in specific ecological niches arethreatened with extinction.WEDNESDAY 14:25 Hall H IIIgtöSociety for Tropical Ecology | Gesellschaft für Tropenökologie e.V. Status and future of tropical biodiversity | Frankfurt, 21 - 24 February 2011gtö