Abstract booklet - gtö – Society for Tropical Ecology

158 PARALLEL SESSION HALL H III THURSDAY ANDEAN BIODIVERSITYPARALLE SESSION THURSDAY H III: ANDEAN BIODIVERSITY HOTSPOT159THURSDAY 17:15 Hall H IIISession: The Andean biodiversity hotspot and its future:Thursday, 24 February, 17:15, Hall H IIIEFFECTS OF GRASS (SETARIA SPHACELATA) COMPETITION ANDFERTILIZATION ON ROOT LENGTH AND BIOMASS ALLOCATION OFNATIVE TREE SPECIES FROM ECUADORBernd Stimm 1 , Ximena Palomeque 1 , Paula Loaiza 1 , Sven Günter 2 , PatrickHildebrandt 1 , Helmut Blaschke 1 , Michael Weber 11TU Muenchen Forest Science, Freising, DE, stimm@forst.wzw.tum.de, 2 CATIE,Turrialba, CRAssessments on plant dynamics have focused primarily on above-groundprocesses, while below-ground processes are less well understood, in particularin tropical forests. Within the context of restoration of degraded lands in thetropics it is well known that Setaria sphacelata is a strong abovegroundcompetitor and limits the suitable establishment of tree seedlings onpasture sites. Moreover, sometimes fertilizers are used to improve the growthperformance of tree species in restoration efforts without understanding thegenuine effect on the establishment of tree species. Therefore, the aim of thisstudy was to detect the effects of grass competition and fertilizer additionon the development of the root system (i.e. total root length and biomassallocation) of three native tree species (Cedrela montana, Tabebuia chrysanthaand Alnus acuminata).We established 60 rhizotrons under nursery conditions in Loja – Ecuador (4rhizotrons/treatment x 5 repetitions x 3 species) where roots were weeklytraced during several months. At the end of the experiment the tree seedlingsand grass were harvested to calculate the above and below ground biomassallocation.The results showed: 1) that with Setaria competition all tree species werestimulated to produce a higher root length to cope with the grass root system,2) tree species and grass had a clear tendency to allocate more on abovegroundthan on belowground biomass, even with fertilization. This is interpreted as astrategy of the seedlings to increase especially its height growth to escapethe grass competition earlier and improve the rate of photosynthesis underthe given environmental conditions. 3) Setaria had higher biomass allocationcompared to tree species and the intensive root system makes it a very efficientcompetitor that can impede vital growth of tree seedlings. A comparisonbetween tree species showed that Alnus was more successful producing both,higher total root length as well as higher above and below ground biomassthan Tabebuia and Cedrela. Therefore, Alnus could be a good candidate to startrehabitation processes on pastures dominated by Setaria.Session: The Andean biodiversity hotspot and its future:Thursday, 24 February, 17:30, Hall H IIIAPPLICATION OF NATIVE ARBUSCULAR MYCORRHIZAL FUNGI FORREFORESTATION WITH NATIVE TREE SPECIES IN SOUTH ECUADORClaudia Krüger 1 , Narcisa Urgiles 1 , Arthur Schüßler 11LMU München, Planegg-Martinsried, DE, claudia.krueger@lrz.uni-muenchen.deEcuador shows the highest deforestation rate in South America and sustainablereforestation programs with native tree species are timely to reduce deforestationpressure on natural forests and to re-establish stable and diverse ecosystems.Most tropical trees strongly depend on associations with arbuscular mycorrhiza(AM) forming fungi, which are obligate symbionts of >80% of land plants. Thesefungi provide large amounts of inorganic nutrients, such as P and N to the plant.In our research area, the Reserva Biológica de San Francisco (RBSF) in South-Ecuador, the vast majority (113/115) of the investigated mountain rainforest treespecies was proven to form AM (Kottke et al. 2008, Ecological Studies 198: 137-148).Our approach was, to relate ecosystem knowledge to sustainable managementpractices, namely afforestation attempts with native, potential crop trees. Thecapability of applying AM fungi (AMF) in a tree nursery for a more efficientreforestation of abandoned pastures (close to the RBSF) was evaluated. NativeAMF were isolated from roots of earlier experiments (Urgiles et al. 2009, NewForest 38: 229-239) and existing reforestation plots, analysed morphologically,DNA barcoded and established as stable cultures with Plantago lanceolata asa plant host (see poster Krüger et al.). Ten cultures were chosen to produce anAMF ‘cocktail’ that was used to inoculate seedlings of three tree species, Cedrelamontana, Heliocarpus americanus and Tabebuia chrysantha. Two samplings wereconducted during the 6-months nursery phase and two during 12-months afteroutplanting at the pastures.We address the question, whether the tree seedlings inoculated with AMF showimproved growth and/or mortality rates. In addition, we monitored the AMF withthe 454FLX-Titanium amplicon sequencing technology and found certain AMF topersist during the nursery phase and also after outplanting. In other experiments,each of the tree species was inoculated with a set of individual AMF and growthperformance was studied. When combined with low fertilization up to 10-timesmore biomass was formed by certain plant-AMF combination in the nursery, ascompared to control treatments.With these approaches we distinguish AMF that preferentially associate with thenative tree seedlings, under nursery condition, and we correlate these data withthe plant performance in the field. The results will allow recommending a moreefficient management strategy for reforestation attempts in Ecuador.THURSDAY 17:30 Hall H IIIgtöSociety for Tropical Ecology | Gesellschaft für Tropenökologie e.V. Status and future of tropical biodiversity | Frankfurt, 21 - 24 February 2011gtö