Das Projekt "Wasserisotope in Wuestenpflanzen: Indikator fuer Pflanzenwasserhaushalt und palaeoklimatologisches Werkzeug fuer die Untersuchung von Klimaaenderungen in anderen Zonen" wird vom Umweltbundesamt gefördert und von GSF - Forschungszentrum für Umwelt und Gesundheit GmbH, Institut für Hydrologie durchgeführt. This research proposal evolved from plant-cellulose studies using environmental isotopes at the GSF-IfH as well as investigations in arid zone hydrology by the Weizmann Institute. The combination of these expertises will permit detailed investigations into the pattern and budget of water use by desert plants. Furthermore, it is anticipated that the investigation of processes will permit development of paleoclimatic and paleo-environmental information. This in turn should permit analyses and interpretation of fossil wood data and determination of past climatic variability. The workplan consists of a round the clock observation and isotopic measurements on representative C3 and C4 plants from an arid zone test site, complemented by growth chamber experiments, on the one hand, and by a survey throughout the Negev desert of plants which can bear relevance to ancient plant material which can be found in the desert. The investigation of water use by desert plants is of immediate socio-economic relevance, with a very significant research component. Paleo-climatic studies relate more to 'understanding the past for prediction of the future' and are important for the assessment of future climatic/environmental changes.