Abstract booklet - gtö – Society for Tropical Ecology

224 SCIENTIFIC POSTER SESSION | FOYERSCIENTIFIC POSTER SESSION | FOYER225WEDNESDAY | FOYERTree xylem flux, leaf conductivity, leaf water potential and leaf photosynthesiswere measured to investigate tree ecophysiological processes during the dryseason. Weather and soil conditions at the sites were recorded by automaticweather stations.During the dry season, from June to the end of September, Polylepis trees showedlittle or no growth at the humid site or even shrunk in diameter presumably dueto cell water storage losses. At the arid site P. rugulosa showed radial (cambial)stem growth. At both sites, soils were very dry. P. racemosa exhibited clear signs ofimpeded plant water uptake from the soil. P. rugulosa seems to be better adaptedto dry soil conditions. Moderate frost events were rare during the observationperiod and did not influence radial tree growth. Apparently, the limiting factor ofgrowth during the dry season was neither air temperature nor air humidity butsoil drought.Topic: The Andean biodiversity hotspot and its future: biodiversity, ecosystemfunctioning and ecosystem services under environmental changeRAINFALL DISTRIBUTION IN THE ANDES OF SOUTHERN ECUADORDERIVED FROM BLENDING WEATHER RADAR DATA ANDMETEOROLOGICAL FIELD OBSERVATIONSRütger Rollenbeck 11Univ. Marburg Geographie, Marburg, DE, rollenbeck@lcrs.deThe Andes of Ecuador show an extreme heterogeneity of spatial and temporaldistribution of precipitation. The existing operational network of the nationalweather service is not capable of reproducing these complex patterns. By usinga cost-efficient rain radar and a network of high-resolution rain gauges, the realcomplexity of the rainfall distribution and the meteorological processes of rainfallformation can be assessed. A blending method encompassing geostatistical toolsallows to derive a comprehensive rainfall climatology for the study area.Precipitation is predominantly of the advective type, associated with humid airmasses from the Amazon basin transported by the tropical easterlies. The typicalform is light to heavy drizzle with long duration but lower rain rates.However, in contrast to former knowledge there is no single mechanism of rainformation for any given place. Several processes interact like small and large-scaleconvective cloud systems, local and regional valley/mountain breeze systems andterrain-lines of preferred moisture transport interact on various time scale. Thisleads to complex patterns of rainfall in space and time.Several types of characteristic weather situations are revealed by the study. Theyare characterized by specific combinations of local and regional atmosphericprocesses andinteractions withthe topographicalconfiguration. They aremodified by mesoscaleand continentalcirculation patterns asthe annual shift ofpressure cells, the eastAndean low level Jetand katabatic flows.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